WO1990012882A1 - Herpes virus recombinant poxvirus vaccine - Google Patents

Abstract

What is described is a recombinant poxvirus, such as vaccinia virus, fowlpox virus and canarypox virus, containing foreign DNA from herpes virus. In one embodiment, the foreign DNA is expressed in a host by the production of a herpes virus glycoprotein. In another embodiment, the foreign DNA is expressed in a host by the production of at least two, particularly two or three, herpes virus glycoproteins. What is also described is a vaccine containing the recombinant poxvirus for inducing an immunological response in a host animal inoculated with the vaccine. By the present invention, the barrier of maternal immunity in a newborn offspring can be overcome or avoided.

Description

HERPES VIRUS RECOMBINANT POXVIRUS VACCINE

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation-in-part of application Serial No. 394,488, filed August 16, 1989, which in turn is a continuation-in-part of application Serial No. 339,004, filed April 17, 1989.

FIELD OF THE INVENTION

The present invention relates to a modified poxvirus and to methods of making and using the same. More in particular, the invention relates to recombinant

poxvirus, which virus expresses gene products of a

herpesvirus gene, and to vaccines which provide protective immunity against herpesvirus infections.

Several publications are referenced in this application by arabic numerals within parentheses. Full citation to these references is found at the end of the specification immediately preceding the claims. These references describe the state-of-the-art to which this invention pertains.

BACKGROUND OF THE INVENTION

Vaccinia virus and more recently other poxviruses have been used for the insertion and expression of foreign genes. The basic technique of inserting foreign genes into live infectious poxvirus involves recombination between pox DNA sequences flanking a foreign genetic element in a donor plasmid and homologous sequences present in the rescuing poxvirus (28).

Specifically, the recombinant poxviruses are constructed in two steps known in the art and analogous to the methods for creating synthetic recombinants of the vaccinia virus described in U.S. Patent No. 4,603,112, the disclosure of which patent is incorporated herein by

reference.

First, the DNA gene sequence to be inserted into the virus, particularly an open reading frame from a non-pox source, is placed into an E. coli plasmid construct into which DNA homologous to a section of DNA of the poxvirus has been inserted. Separately, the DNA gene sequence to be inserted is ligated to a promoter. The promoter-gene linkage is positioned in the plasmid construct so that the promoter-gene linkage is flanked on both ends by DNA

homologous to a DNA sequence flanking a region of pox DNA containing a nonessential locus. The resulting plasmid construct is then amplified by growth within E. coli

bacteria (11) and isolated (12, 20).

Second, the isolated plasmid containing the DNA gene sequence to be inserted is transfected into a cell culture, e.g. chick embryo fibroblasts, along with the poxvirus. Recombination between homologous pox DNA in the plasmid and the viral genome respectively gives a poxvirus modified by the presence, in a nonessential region of its genome, of foreign DNA sequences. The term "foreign" DNA designates exogenous DNA, particularly DNA from a non-pox source, that codes for gene products not ordinarily produced by the genome into which the exogenous DNA is placed.

Genetic recombination is in general the exchange of homologous sections of DNA between two strands of DNA. In certain viruses RNA may replace DNA. Homologous sections of nucleic acid are sections of nucleic acid (DNA or RNA) which have the same sequence of nucleotide bases.

Genetic recombination may take place naturally during the replication or manufacture of new viral genomes within the infected host cell. Thus, genetic recombination between viral genes may occur during the viral replication cycle that takes place in a host cell which is co-infected with two or more different viruses or other genetic

constructs. A section of DNA from a first genome is used interchangeably in constructing the section of the genome of a second co-infecting virus in which the DNA is homologous with that of the first viral genome.

However, recombination can also take place between sections of DNA in different genomes that are not perfectly homologous. If one such section is from a first genome homologous with a section of another genome except for the presence within the first section of, for example, a genetic marker or a gene coding for an antigenic determinant

inserted into a portion of the homologous DNA, recombination can still take place and the products of that recombination are then detectable by the presence of that genetic marker or gene in the recombinant viral genome.

Successful expression of the inserted DNA genetic sequence by the modified infectious virus requires two conditions. First, the insertion must be into a

nonessential region of the virus in order that the modified virus remain viable. The second condition for expression of inserted DNA is the presence of a promoter in the proper relationship to the inserted DNA. The promoter must be placed so that it is located upstream from the DNA sequence to be expressed.

There are two subtypes of equine herpesvirus that, although they contain cross-neutralizing epitopes, can be distinguished by their antigenic profiles, restriction endonuclease fingerprints and their pathogenicity for horses (1). Equine herpesvirus 1 (EHV-1) is associated with respiratory tract disease, central nervous system disorders and classic herpetic abortions whereas equine herpesvirus 4 (EHV-4) is predominantly associated with respiratory tract disease (1,48). Equine herpesviruses are members of the alphaherpesvirus subfamily and display many of the typical biological and biochemical characteristics of human

herpesviruses, such as genomic isomerization, regulation of gene expression, establishment of latent infections, generation of defective interfering virus particles, induction of neurological disorders, and in vitro oncogenic transformation (1,4,23). Thus, EHV advantageously can be used for studying the varied biological consequences of herpesvirus infections.

Herpesvirus glycoproteins mediate essential viral functions such as cellular attachment and penetration, cell to cell spread of the virus and, importantly, determine the pathogenicity profile of infection. Herpesvirus

glycoproteins are critical components in the interaction with the host immune system (36,37).

The well characterized glycoproteins of herpes simplex virus include gB, gC, gD, gE, gG, gH and gl

(36,37,49-55). A number of studies have indicated the importance of herpes simplex virus glycoproteins in eliciting immune responses. Hence, it has been reported that gB and gD can elicit important immune responses

(6,8,13,18,21,22,26,27,30,44,46,47). gC can stimulate class I restricted cytotoxic lymphocytes (15,32) whereas gD can stimulate class II cytotoxic T cell responses

(21,22,44,46,47). gG was shown to be a target for

complement-dependent antibody directed virus neutralization (38,39). A number of glycoproteins from other herpesviruses have also been shown to elicit important immune responses (5,10,36,56).

Both subtypes of EHV express six abundant glycoproteins (1,3,43). The genomic portions of the DNA sequences encoding gp2, gp10, gp13, gp14, gp17/18, and gp21/22a have been determined using lambda gtll expression vectors and monoclonal antibodies (3). Glycoproteins gp13 and gp14 were located in the same locations within the L component of the genome to which the gC and gB homologs, respectively, of herpes simplex virus map (3). EHV-1 appears unique among the alphaherpesviruses whose

glycoprotein genes have been mapped in that five of its six major glycoproteins are encoded from sequences within the genome L component while only one (gp17/18) is mapped to the U_s region. Analyzing these data, it has been predicted that some of the low-abundance glycoproteins identified in EHV-1 virions as well as EHV-1 glycoproteins not yet identified map to the S component of the genome (3). The envelope glycoproteins are the principal immunogens of herpesviruses involved in eliciting both humoral and cellular host immune responses (5,8,73-75) and so are of the highest interest for those attempting to design vaccines.

Recently, the nucleotide sequence of the Kentucky T431 strain of the EHV-1 transcriptional unit encoding gp13 has been reported (2). An open reading frame encodes a 468 amino acid primary translation product of 51 kDa. The protein has the characteristic features of a membrane- spanning protein with nine potential N-linked glycosylation sites (Asn-X-Ser/Thr) present in the surface domain between the putative signal and transmembrane anchor portions of the protein (2). The glycoprotein was shown to be homologous to the herpes simplex virus (HSV) gC-1 and gC-2, to the

pseudorabies virus (PRV) gill and the varicella-zoster virus (VZV) gpV (2). EHV-1 gp13 is thus the structural homolog of the herpesvirus gC-like glycoproteins.

The nucleotide sequence of EHV-1 gp14 (71,72) has recently been reported. Analysis of the predicted amino acid sequence of gp14 glycoprotein revealed significant homology to the corresponding glycoprotein of HSV, gB.

Monoclonal antibodies directed against some EHV-1 glycoproteins have been shown to be neutralizing (76).

Passive immunization experiments demonstrated that

monoclonal antibodies directed against gp13 or gp14 (77) or against gp13, gp14 or gp17/18 (78) could protect hamsters against a lethal challenge. Other gB and gC glycoprotein analogs are also involved in protection against diseases caused by alphaherpesviruses (8,10,73). The EHV-1 gp17/18 glycoprotein, although characterized as another potential protective immunogen, had until now no known structural counterpart among the several glycoproteins encoded from the S component in the other alphaherpesviruses (66,79,80).

Based on its genomic position, it has been speculated that gp17/18 could be the HSV gE analog (2).

Pseudorabies virus (PRV), an alphaherpesvirus, is the causative agent of Aujesky's disease. The disease is highly infectious causing serious economic losses in the swine industry. The disease is associated with high

morbidity and mortality among piglets and is characterized by severe respiratory illness, abortions, reduced litter size and decreased growth rates of survivors. Fatal

encephalitis is a frequent consequence of infection. Latent viral infections, a characteristic of herpes viruses, can be established thus allowing recovered adult swine to serve as chronic carriers of the virus. For a recent extensive review see Wittmann and Rziha (81).

The PRV genome consists of a 90 x 10⁶ dalton double stranded DNA (82) separated by inverted repeat sequences into unique long (U_L) or unique short (U_s)

segments (83,84). The PRV genome encodes approximately 100 polypeptides whose expression is regulated in a cascade-like fashion similar to other herpesviruses (85, 86). To date, five glycoproteins gpl, gpli, gpIII, gp63 and gp50 have been shown to be associated with the viral envelope and

associated with the various membranous structures of PRV infected cells (80,86-91). A sixth PRV encoded glycoprotein (gX) is released into the culture medium (92). The physical location of these glycoproteins on the PRV genome and their DNA sequence are currently known (62,80,91-98). As with the glycoproteins of other herpesviruses, the PRV glycoproteins mediate essential viral functions such as cellular

attachment and penetration into or release from cells. The PRV glycoproteins are critical in the pathogenicity profile of PRV infection and are critical components in the

resolution of disease and the immune status.

PRV gpl is non-essential for virus replication in vitro and in vivo and is absent from most attenuated PRV strains (99). The attenuated nature of these gl-deleted strains also indicates a possible role for gl in virulence (99,100). Other PRV proteins, however, appear to be

involved in this function since expression of gl alone is not sufficient to produce high levels of virulence (100).

The role gl plays in eliciting an immune response against PRV is unclear. Monoclonal antibodies against gl can neutralize virus in vitro (101) and passively protect immunized mice against a lethal PRV challenge (81). Kost et al. (98) have recently described the expression of PRV gpl in vaccinia virus recombinants either alone or in

association with gp50 and gp63. Intracranial inoculation of the vaccinia recombinants in mice resulted in increased virulence particularly when PRV gpl was associated with coexpression of gp50 and gp63.

In swine, however, neutralizing antibodies against gl are not produced (5). In addition, a recombinant

vaccinia virus expressing PRV gl-encoded polypeptides (98) does not protect mice against a lethal PRV challenge

(relative to the protection afforded by the wildtype vaccinia virus control). These data, taken together, suggest that PRV gpl is more appropriate as a diagnostic probe rather than as a component in a subunit vaccine. PRV glycoprotein gp63 is located adjacent to gp50 in the U_s region of the PRV genome (80). The coding

sequence for PRV gp63 starts with three consecutive ATG codons approximately 20 nucleotides downstream from the stop codon of gp50. There is no recognizable transcriptional signal motif and translation probably occurs from the same transcript as gp50. PRV gp63 is non-essential in vitro

(88). PRV gp63 as a continuous DNA sequence with PRV gp50 has been expressed in vaccinia virus as reported by Kost et al. (98). The contribution of PRV gp63 to protection in mice against PRV challenge is difficult to assess since those studies did not dissect the contributions of PRV gp50 and gp63.

PRV glycoprotein gX is a non-structural glycoprotein whose end product is secreted into the

extracellular fluid (85,92). No in vitro neutralization of PRV was obtained with either polyclonal or monoclonal sera to PRVgX (102,103) and subunit gX vaccines were non- protective against challenge (104).

PRV glycoprotein gp50 is the Herpes simplex virus type 1 (HSV-1) gD analog (97). The DNA open reading frame encodes 402 amino acids (95). The mature glycosylated form (50-60 kDa) contains O-linked carbohydrate without N-linked glycosylation (95). Swine serum is highly reactive with PRV gp50, suggesting its importance as an immunogen. Monoclonal antibodies to gp50 neutralize PRV in vitro with or without complement (97,105,106) and passively protect mice

(102,105,106) and swine (102). Vaccinia virus recombinants expressing PRV gp50 induced serum neutralizing antibodies and protected both mice and swine against lethal PRV

challenge (98,107,108).

The PRV gpIII gene is located in the U_L region of the genome. The 1437 bp open reading frame encodes a protein of 479 amino acids. The 50.9 kDa deduced primary translation product has eight potential N-linked

glycosylation sites (96). PRV gill is the HSV-1 gC analog (96). Functional replacement of PRV gill by HSVgC was not observed (109). Although PRV gill is nonessential for replication in vitro (110 , 111) , the mature glycosylated form (98 kDa) is an abundant constituent of the PRV envelope.

Anti-gpIII monoclonal antibodies neutralize the virus in vitro with or without complement (86 , 106 , 110) and can passively protect mice and swine (102). The PRV

glycoprotein gill can protect mice and swine from lethal PRV challenge after immunization with a Cro/glll fusion protein expressed in E. coli (Robbins, A., R. Watson, L. Enquist, European Patent application 0162738A1) or when expressed in a vaccinia recombinant (Panicali, D., L. Gritz, G. Mazzara, European Patent application 0261940A2).

One of the main constituents of the PRV envelope is a disulfide linked complex of three glycoproteins (120 kDa, 67 kDa and 58 kDa) designated as PRV gpll according to the nomenclature of Hampl (86). The DNA sequence encoding PRV gpll is located in the left end of U_L. The open reading frame of 2976 nucleotides encodes a primary translation product of 913 amino acids or 110 kDa. PRV gpll is the HSV- 1 gB homolog (62). Monoclonal antibodies directed against PRV gpll have been shown to neutralize the virus in vitro (5) with or without complement (81). Moreover, passive immunization studies demonstrated that neutralizing

monoclonal antibodies partially protected swine but failed to protect mice from virulent virus challenge (102). To date, the active immunization of swine with PRV gpll

glycoprotein has not been reported.

During the past 20 years the incidence of genital infections caused by herpes simplex virus type 2 (HSV2) has increased significantly. Recent estimates indicate that in the United States, 5-20 million people have genital herpes (112). Although oral treatment with acyclovir has been shown to reduce the severity of primary infections (113) and to suppress recurrent episodes (114), the control and treatment of these infections is far from ideal. A vaccine to prevent primary and recurrent infections is therefore needed.

The herpes simplex virus type 1 (HSV1) genome encodes at least eight antigenically distinct glycoproteins: gB, gC, gD, gE, gG, gH, gl and gJ (115). Homologues for these genes appear to be present in HSV2 (116-119). Since these glycoproteins are present in both the virion envelope and the infected cell plasma membrane, they can induce humoral and cell-mediated protective immune responses (37).

The relative importance of humoral and cellular immunity in protection against herpes simplex virus

infections has not been completely elucidated. Mice

immunized with purified HSV1 gB, gC or gD are protected against lethal HSV1 challenge (120). Mice have also been protected against lethal HSV1 or HSV2 challenge by passive immunization with antibodies to total HSV1 (121) or HSV2 (122) virus and with antibodies to the individual HSV2 gB, gC, gD or gE glycoproteins (123). This protection, however, appears to be dependent upon a competent T-cell response since animals immunosuppressed by irradiation,

cyclophosphamide or anti-thymocyte serum were not protected (124).

The contribution of the individual glycoproteins in eliciting a protective immune response is not completely understood. Expression of these glycoproteins in a

heterologous system, such as vaccinia, has allowed some of these parameters to be analyzed. For example, vaccinia virus vectors expressing HSV1 gB (125) and HSV1 gC (32) have been shown to induce cytotoxic T-cell responses. In

addition, it has been shown that mice immunized with

recombinant vaccinia virus expressing either HSV1 gB (8), HSV1 gC (126) or HSV1 gD (26) are protected against a lethal challenge of HSV1. A recombinant vaccinia virus expressing HSV1 gD has also been shown to be protective against HSV2 in a guinea pig model system (44). It is not known, however, whether expression of multiple HSV antigens will result in a potentiation of this protective response.

Bovine herpesvirus 1 (BHV1) is responsible for a variety of diseases in cattle, including conjunctivitis, vulvovaginitis and abortion (127). It is also one of the most important agents of bovine respiratory disease, acting either directly or as a predisposing factor for bacterial infection (128).

BHV1 specifies more than 30 structural polypeptides, 11 of which are glycosylated (129). Four of these glycoproteins, gl, gll, gill and gIV, have been characterized and found to be homologous to the herpes simplex virus (HSV) glycoproteins gB, gC, gD, and gE

(130,131).

Subunit vaccines consisting of gl, gIll and/or gIV have been shown to protect cattle from disease (using a BHVl/Pasteurella haemolytica aerosol challenge model) but not from infection (132). These results indicate the importance of these glycoproteins in eliciting a successful immune response against BHV1.

gl and gIll have also been cloned into vaccinia virus and cattle immunized with these recombinants are shown to produce neutralizing antibodies to BHV1 (56,133).

Feline rhinotracheitis is a common and worldwide disease of cats which is caused by an alphaherpesvirus designated feline herpesvirus type 1 (FHV-1). Like other herpesviruses, FHV-1 establishes a latent infection which results in periodic reactivation (134). FHV-1 infections in breeding colonies are characterized by a high rate of mortality in kittens. Secondary infections of the upper respiratory tract are quite debilitating in adults. The control of this disease is currently attempted by using modified live or inactivated vaccines which can suppress the development of clinical signs but do not prevent infection that results in shedding of virus. Thus, asymptomatic vaccinated cats can spread virulent virus and latent

infections cannot be prevented by existing vaccines (135) or by the safer purified subunits vaccines under development (136,137).

Herpesvirus glycoproteins mediate attachment of the virion to the host cell and are extremely important in viral infectivity (138,139). They also determine the subtype specificity of the virus (140). Herpesvirus

glycoproteins antigens are recognized by both the humoral and cellular immune systems and have been shown to evoke protective immune responses in vaccinated hosts

(44,107,141,142). FHV-1 has been shown to contain at least 23 different proteins (143,144). Of these, at least five are glycosylated (144,145) with reported molecular masses ranging from 120 kDa to 60 kDa. The FHV-1 glycoproteins have been shown to be immunogenic (143,145).

Like several other alphaherpesviruses, FHV-1 appears to have a homolog of glycoprotein B (gB) of HSV-1, and partial sequence of the FHV-1 gB gene has recently been reported (146). The HSV-1 gB is required for virus entry and for cell fusion (147-149). The HSV-1 gB and the gB analogs of other herpesviruses have been shown to elicit important circulating antibody as well as cell-mediated immune

responses (8,10,37,47,73,150). The FHV-1 gB glycoprotein is a 134 kDa complex which is dissociated with B- mercaptoethanol into two glycoproteins of 66 kDa and 60 kDa. The FHV-1 DNA genome is approximately 134 Kb in size (153).

Epstein Barr Virus (EBV), a human B lymphotropic herpesvirus, is a member of the genus lymphocryptovirus which belongs to the subfamily gammaherpesvirus (115). It is the causative agent of infectious mononucleosis (154) and of B-cell lymphomas (156). EBV is associated with two human malignancies: the endemic Burkitt's lymphoma and the

undifferentiated nasopharyngeal carcinoma (156).

Since the EBV genome was completely sequenced (207) as the genomes of VZV (66) and HSV1 (158) numerous homologies between these different herpesviruses have been described (159). In some cases these homologies have been used to predict the potential functions of some open reading frame (ORFs) of EBV. The EBV genes homologous to the HSV1 genes involved in immunity are of particular interest. So the EBV BALF4 gene has homologies with HSV1 gB (68) and the EBV BXLF2 gene with HSV1 gH (161). Finally, the EBV BBRF3 gene contains homologies with a CMV membrane protein (162).

Among the EBV proteins, the two major envelope glycoproteins gp340 and gp220 are the best characterized potential vaccinating antigens. They are derived from the same gene by splicing without a change in the reading frame (163,164). Monoclonal antibodies and polyclonal sera directed against gp340 neutralize EBV in vitro (165). The cottontop tamarinds, the only susceptible animal, can be protected by an immunization with purified gp340 (166) and with a recombinant EBV gp340 vaccinia virus (167). In this case, the protection was achieved with a recombinant derived from the WR vaccinia strain but not with a recombinant derived from the Wyeth vaccinia strain. The Wyeth strain has been widely used as a vaccine strain.

Monoclonal antibodies directed against the gp85, the EBV homologue to HSV1 gH, have been described as in vitro neutralizing antibodies (168,169).

Human cytomegalovirus (HCMV) is a member of the betaherpesvirinae subfamily (family Herpesviridae). HCMV can produce a persistent productive infection in the face of substantial specific immunity. Even if HCMV possesses a low pathogenicity in general, intrauterine infection causes brain damages or deafness in about 0.15% of all newborns and it is the most common infectious complication of organ transplantation (170). Although the efficacy of an

experimental live attenuated (Towne strain) HCMV vaccine has been demonstrated (171), concerns about live vaccine strains have directed efforts towards the identification of HCMV proteins usable as a subunit vaccine. In this prospect the identification of virion glycoproteins and their evaluation as protective agents is an important step.

Three immunologically distinct families of

glycoproteins associated with the HCMV envelope have been described (172): gCI (gp55 and gp93-130); gCII (gp47-52); and gCIII (gp85-p145).

The gene coding for gCI is homologous to HSVl gB. The gCII glycoproteins are coded by a family of five genes (HXLF) arranged in tandem and sharing one or two regions of homology. More probably gCII is coded by only two of these genes (172,173). The gene coding for gCIII is homologous to HSVl gH (174).

In vitro neutralizing antibodies specifically directed against each of these families have been described (174-176).

Suitably modified poxvirus mutants carrying exogenous equine herpesvirus genes which are expressed in a host as an antigenic determinant eliciting the production by the host of antibodies to herpesvirus antigens represent novel vaccines which avoid the drawbacks of conventional vaccines employing killed or attenuated live organisms.

Thus, for instance, the production of vaccines from killed organisms requires the growth of large quantities of the organisms followed by a treatment which will selectively destroy their infectivity without affecting their

antigenicity. On the other hand, vaccines containing attenuated live organisms always present the possibility of a reversion of the attenuated organism to a pathogenic state. In contrast, when a recombinant poxvirus suitably modified with an equine herpesvirus gene coding for an antigenic determinant of a disease-producing herpesvirus is used as a vaccine, the possibility of reversion to a

pathogenic organism is avoided since the poxvirus contains only the gene coding for the antigenic determinant of the disease-producing organism and not those genetic portions of the organism responsible for the replication of the

pathogen.

PRV fatally infects many mammalian species

(cattle, dogs, etc.). Adult pigs, however, usually survive infection and therefore represent an important virus

reservoir. Because PRV causes severe economic losses, vaccination of pigs with attenuated or killed vaccines is performed in many countries.

Attempts to control PRV infection in swine and to reduce economic losses have been made by active immunization with modified live or inactivated vaccines. Attenuated vaccines which generally induce long lasting immunity and are cost efficient present the risk of insufficient

attenuation or genetic instability. Inactivated vaccines are less efficient, require several immunizations and usually contain potent adjuvants. These latter formulations can induce post-vaccinal allergic reactions such as lack of appetite, hyperthermia or abortion in pregnant sows. These vaccine types also suffer from certain drawbacks with respect to prevention of latent infections, overcoming the effects of maternal antibodies on vaccination efficacy, and eliminating the potential use of a serological diagnostic assay to distinguish vaccinated animals from those

previously infected with PRV. Alternative vaccination strategies such as the use of recombinant poxviruses that express immunologically pertinent PRV gene products would have certain advantages: (a) eliminate live attenuated PRV vaccine strains from the field; and (b) allow the distinction of vaccinated versus infected or seropositive animals. The latter could be accomplished by the use of appropriate diagnostic reagents that would precisely distinguish vaccinated from naturally infected animals. This is an important consideration because of existing regulations controlling the movement of seropositive animals. Further, vaccination is more

economical and preferable to testing and eliminating

infected animals from the lots. The development of such vaccines requires a knowledge of the contributions made by appropriate PRV antigens to the induction of protective immunity. In the case of PRV, as with other members of the herpesvirus family, the glycoproteins are important

candidates for antigens to be present in an effective subunit recombinant vaccine.

The technology of generating vaccinia virus recombinants has recently been extended to other members of the poxvirus family which have a more restricted host range. In particular, avipoxviruses, which replicate in avian species, have been engineered to express immunologically pertinent gene products. Inoculation of avian (42,177) and non-avian species (41) with avipoxvirus recombinants

elicited protective immune responses against the

corresponding pathogen.

Attenuated live vaccines and inactivated vaccines to BHV1 have been available for over 30 years and have successfully reduced the incidence of BHVl related diseases. These vaccines, however, do not prevent latent infection or reinfection with wildtype virus. They also complicate the differentiation between infected and vaccinated animals.

Both types of vaccines have other significant drawbacks. Vaccination of pregnant cows with attenuated live vaccines can cause fetal death and subsequent abortion (127). In addition, vaccinated animals have been shown to shed virus (178). Therefore, vaccinated animals kept with pregnant cows can spread infectious virus to the pregnant animal and cause abortion of the fetus.

Inactivated vaccines do not induce abortions or provoke viral excretion. However, they necessitate the use of adjuvants and can cause fatal hypersensitivity reactions (anaphylaxis) and nonfatal inflammation and fever (179).

One of the more important issues in vaccination is overcoming or avoiding maternal immunity. In this respect, if a mother is immune to a particular pathogen, the

"immunity" in the mother will be passed on to the newborn via the antibodies present in the colostrum and/or by additional pathways. Nevertheless, the newborn cannot be successfully vaccinated until the level of maternal immunity has waned sufficiently. Therefore, there is a narrow window where the newborn can be successfully vaccinated in the presence of waning maternal immunity.

It can thus be appreciated that provision of a herpesvirus recombinant poxvirus, and of vaccines which provide protective immunity against herpesvirus infections, which confer on the art the advantages of live virus

inoculation but which reduce or eliminate the previously discussed problems would be a highly desirable advance over the current state of technology.

OBJECTS OF THE INVENTION

It is therefore an object of this invention to provide recombinant poxviruses, which viruses express gene products of herpesvirus, and to provide a method of making such recombinant poxviruses.

It is an additional object of this invention to provide for the cloning and expression of herpesvirus coding sequences in a poxvirus vector, particularly a vaccinia virus, fowlpox virus or canarypox virus vector.

It is another object of this invention to provide a vaccine which is capable of eliciting herpesvirus

neutralizing antibodies and protective immunity against a lethal herpesvirus challenge.

These and other objects and advantages of the present invention will become more readily apparent after consideration of the following. STATEMENT OF THE INVENTION

In one aspect, the present invention relates to a recombinant poxvirus containing therein a DNA sequence from herpesvirus in a nonessential region of the poxvirus genome. Advantageously, the herpesvirus is a member of the

alphaherpesvirus, betaherpesvirus or gammaherpesvirus subfamily. In particular, the DNA sequence from herpesvirus codes for a herpesvirus glycoprotein. More in particular, the herpesvirus glycoprotein is selected from the group consisting of equine herpesvirus gp13, equine herpesvirus gp14, equine herpesvirus gD, equine herpesvirus gp63, equine herpesvirus gE, pseudorabies virus gp 50, pseudorabies virus gpll, pseudorabies virus gpIII, pseudorabies virus gpl, herpes simplex virus gB, herpes simplex virus gC, herpes simplex virus gD, bovine herpes virus gl, feline herpes virus gB, Epstein-Barr virus gp220, Epstein-Barr virus gp340, Epstein-Barr virus gB, Epstein-Barr virus gH and human cytomegalovirus gB.

According to the present invention, the recombinant poxvirus expresses gene products of the foreign herpesvirus gene. In particular, the foreign DNA sequence codes for a herpesvirus glycoprotein and the foreign DNA is expressed in a host by the production of the herpesvirus glycoprotein. Advantageously, a plurality of herpesvirus glycoproteins are coexpressed in the host by the recombinant poxvirus. The poxvirus is advantageously a vaccinia virus or an avipox virus, such as fowlpox virus or canarypox virus.

In another aspect, the present invention relates to a vaccine for inducing an immunological response in a host animal inoculated with the vaccine, said vaccine including a carrier and a recombinant poxvirus containing, in a nonessential region thereof, DNA from herpesvirus.

More in particular, the DNA codes for and expresses a herpesvirus glycoprotein. Advantageously, a plurality of herpesvirus glycoproteins are coexpressed in the host by the poxvirus. The poxvirus used in the vaccine according to the present invention is advantageously a vaccinia virus or an avipox virus, such as fowlpox virus or canarypox virus. In another aspect, the present invention relates to mechanisms to bypass the issue of maternal immunity. If the barrier is due to the presence of antibodies to a given antigen(s) then the barrier of maternal immunity may be overcome or avoided by using, selectively, vectors

expressing defined subsets of antigens. For example, the pregnant animal can be vaccinated with a recombinant

vaccinia virus expressing pseudorabies virus glycoprotein gp50 and the offspring can be vaccinated at birth or shortly thereafter with vaccinia recombinants expressing other pseudorabies virus glycoproteins gpll or gpIII or

combinations thereof. On the other hand, if the barrier presented by maternal immunity is due to the vector then one may differentially vaccinate the mother with one vector (vaccinia or avipox) and vaccinate the offspring with the other vector. This procedure, of course, takes into

consideration not only the use of different vectors but also vectors expressing a different constellation of

glycoproteins. Thus, the present invention relates to a method for overcoming or avoiding maternal immunity which would otherwise prevent successful immunization in a newborn offspring. By the present invention, the newborn offspring is inoculated with a recombinant poxvirus containing therein DNA from a non-pox source in a nonessential region of the poxvirus genome, said DNA coding for a first antigen of a pathogen of the newborn offspring, and said antigen being different from a second antigen of the same pathogen used to induce an immunological response to the same pathogen in the mother of the newborn offspring. Also by the present invention, the newborn offspring is inoculated with a recombinant first poxvirus containing therein DNA from a non-pox source in a nonessential region of the first

poxvirus genome, said DNA coding for an antigen of a

pathogen of the newborn offspring, and said first poxvirus being different from a recombinant second poxvirus used to induce an immunological response to the same pathogen in the mother of the newborn offspring. BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will be had by referring to the accompanying drawings, in which:

FIG. 1 schematically shows a method for the construction of the recombinant vaccinia virus vP425;

FIG. 2 shows the DNA sequence of an EHV-1 1.88 Kb fragment containing the gp13 coding sequences;

FIG. 3 schematically shows a method for the construction of the recombinant vaccinia virus vP483

containing the EHV-1 gp13 gene;

FIG. 4 schematically shows a method for the construction of the recombinant vaccinia virus vP458;

FIG. 5 schematically shows a method for the construction of the recombinant vaccinia virus vP577

containing the EHV-1 gp14 gene;

FIG. 6 shows the DNA sequence of an EHV-1 3.35 Kb fragment containing the gp14 coding sequence;

FIG. 7 is a plot of relative hydrophilicity for the EHV-1 gp14 coding sequences;

FIG. 8 schematically shows a method for the construction of the recombinant fowlpox virus vFP44

containing the EHV-1 gp13 gene;

FIG. 9 schematically shows a method for the construction of the recombinant canarypox virus vCP48 containing the EHV-1 gp13 gene;

FIG. 10 schematically shows a method for the construction of donor plasmids pHES-MP63, pHES-MPl and pHES- MP34 containing modified versions of the EHV-1 gp14 gene;

FIG. 11 is a map of the BamHI cleavage sites of the EHV-1 Kentucky D strain indicating the inverted repeats of the genome by boxes, showing the location of the six major EHV-1 glycoprotein genes and showing an expansion of the region of the genome which includes the gD, gp63 and gE genes;

FIG. 12 shows the nucleotide sequence of an EHV-1 6402 base-pair fragment containing the gD, gp63 and gE coding sequences; FIG. 13 is a hydropathy plot of the sequence of 402 amino acids composing EHV-1 gD;

FIG. 14 is a hydropathy plot of the sequence of 413 amino acids composing EHV-1 gp63;

FIG. 15 is a hydropathy plot of the sequence of

552 amino acids composing EHV-1 gE;

FIG. 16 schematically shows a method for the construction of donor plasmids pJCA006, pJCA007 and pJCA008 containing the EHV-1 gD gene, the EHV-1 gE gene and the EHV- 1 gp63 gene, respectively, and generation of recombinant vaccinia virus containing these genes;

FIG. 17 schematically shows a method for the construction of donor plasmids pJCA009 (containing the EHV-1 gD and gp63 genes) and pJCA010 (containing the EHV-1 gD, gp63 and gE genes), and generation of recombinant vaccinia virus containing these genes;

FIG. 18 schematically shows a method for the construction of donor plasmid PR18 containing the PRV gpll gene, and generation of recombinant vaccinia virus

expressing the PRV gpll gene;

FIG. 19 shows the DNA sequence of the PRV gpll open reading frame;

FIG. 20 schematically shows a method for the construction of donor plasmid pPR24 containing the PRV gpIII gene, and generation of recombinant vaccinia virus

expressing the PRV gpIII gene;

FIG. 21 shows the DNA sequence of the PRV gpIII open reading frame;

FIG. 22 schematically shows a method for the construction of donor plasmid pPR26 containing the PRV gp50 gene, and generation of recombinant vaccinia virus

expressing the PRV gp50 gene;

FIG. 23 shows the DNA sequence of the PRV gp50 open reading frame;

FIG. 24 schematically shows a method for the construction of plasmid pSD478VC, and pSD479VCBG and insertion of Beta-galactoside into vaccinia virus;

FIG. 25 schematically shows a method for the construction of plasmid pMP13PP; FIG. 26 schematically shows a method for the construction of plasmid pFPPRVII containing the PRV gpll gene;

FIG. 27 schematically shows a method for the construction of the recombinant canarypox virus vCP55 expressing the PRV gpll gene;

FIG. 28 schematically shows a method for the construction of the recombinant vaccinia virus vP717

expressing the PRV gl gene;

FIG. 29 schematically shows a method for the construction of recombinant vaccinia viruses vP569 and vP734 expressing the HSV-2 gB gene;

FIG. 30 schematically shows a method for the construction of recombinant vaccinia viruses vP579, vP748 and vP776 expressing the HSV-2 gC gene;

FIG. 31 schematically shows a method for the construction of recombinant vaccinia viruses vP570, vP761, vP775 and vP777 expressing the HSV-2 gD gene;

FIG. 32 schematically shows a method for the construction of recombinant vaccinia viruses vP637 and vP724 expressing the BHV-1 gl gene;

FIG. 33 schematically shows a method for the construction of donor plasmid pJCA001 containing the FHV-1 gB gene and for the construction of the recombinant vaccinia virus VP713 expressing the FHV-1 gB gene;

FIG. 34 shows the nucleotide sequence of the 3400 bp segment of FHV-1 DNA encoding glycoprotein gB;

FIG. 35 is a hydropathy plot of the sequence of 947 amino acids composing FHV-1 gB;

FIG. 36 schematically shows a method for the construction of donor plasmids 409gp220 containing the EBV gp220 gene and 409gp340 containing the EBV gp340 gene;

FIG. 37 schematically shows a method for the construction of vaccinia donor plasmid 409gB containing the EBV gB gene;

FIG. 38 schematically shows a method for the construction vaccinia donor plasmid 486gH containing the EBV gH gene; FIG. 39 schematically shows the structure of the vaccinia donor plasmid 513gHgBgp340 containing the EBV genes gp340, gB and gH;

FIG. 40 schematically shows a method for the construction of vaccinia donor plasmid 409CMVgB containing the CMV gB gene;

FIG. 41 shows the nucleotide and amino acid sequences of HCMV (Towne strain) HXLF1 gene; and

FIG. 42 shows the nucleotide and amino acid sequences of HCMV (Towne strain) HXLF2 gene.

DETAILED DESCRIPTION OF THE INVENTION

A better understanding of the present invention and of its many advantages will be had from the following examples, given by way of illustration.

Example 1 - CONSTRUCTION OF VACCINIA VIRUS RECOMBINANTS

EXPRESSING THE EQUINE HERPESVIRUS gp13

GLYCOPROTEIN

Replacement of the HA gene of vaccinia with the E. coli Beta-cralactosidase gene. The Copenhagen strain of vaccinia virus obtained from Rhone Merieux, Inc. (Athens, Georgia) was utilized in this example. The virus was propagated from a purified plaque isolate on either VERO (ATCC# CCL81) or MRC-5 (ATCC# CCL171) cells in Eagle's minimal essential medium (MEM) plus 10% fetal bovine serum (FBS). A derivative of the wildtype virus from which the entire coding sequence for the thymidine kinase gene was deleted by standard methods (25,28) was isolated and

designated vP410. This thymidine kinase deletion mutant was used for further manipulations. Plasmids were constructed, screened, and grown by standard procedures (20,27,28).

Referring now to FIG. 1, the 13 Kb Sall F fragment of vaccinia virus which spans the Hindlll A/B fragment junction was ligated into Sall digested pUC8 generating pSD419VC. The right arm of pSD419VC corresponding to the Hindlll B portion of the Sall F fragment was removed by digestion with Hindlll and religation generating pSD456VC. pSD456VC thus contains the right end of the Hindlll A fragment within which is the complete coding region for the hemagglutinin (HA) gene (35) flanked by approximately 0.4 Kb additional vaccinia sequences on each side.

To generate a plasmid vector virtually devoid of HA coding sequences, pSD456VC was cut (partial digest) at the Rsal site upstream of the HA gene and at the Eagl site 80 bp from the 3' end of the HA gene. The approximate 3.5 Kb Rsal/Eagl fragment was isolated from an agarose gel.

Synthetic oligonucleotides MPSYN59-62 were

prepared to replace the region from the Rsal site through position 2 upstream of the HA coding sequence, immediately followed by Bglll, Smal and PstI restriction sites and an Eagl sticky end. The sequence of MPSYN59-62, with

restriction sites as indicated, is as follows:

5'-ACACGAATGATTTTCTAAAGTATTTGGAAAGTTTTATAGGTAGTTGATAGAACAA

3'-TGTGCTTACTAAAAGATTTCATAAACCTTTCAAAATATCCATCAACTATCTTGTT

AATACATAATTTTGTAAAAATAAATCACTTTTTATACTAAGATCTCCCGGGCTGCAGC-3'

TTATGTATTAAAACATTTTTATTTAGTGAAAAATATGATTCTAGAGGGCCCGACGTCGCCGG-5'

Bglll Smal PstI EagI

The annealed MPSYN59-62 mixture was ligated into the 3.5 Kb Rsal/Eagl fragment from pSD456VC, generating pSD466VC.

Thus, in pSD466VC the HA gene has been replaced by a

polylinker region.

A 3.2 Kb Bglll/BamHI (partial) fragment containing the E. coli Beta-galactosidase gene from pMC1871 (34) under the transcriptional control of the vaccinia 11 kDa promoter (7) was cloned into pSD466VC which had been digested with Bglll. A plasmid containing the 11 kDa promoter/Beta- galactosidase gene cassette in a left to right orientation relative to flanking vaccinia arms was designated

pSD466VCBGA and recombined into a thymidine kinase deletion mutant, vP410, of the Copenhagen strain of vaccinia virus generating the vaccinia recombinant vP425 expressing Beta- galactosidase. Eighty base pairs at the carboxy terminus of the HA gene were retained so not to disrupt a short

potential open reading frame transcribed right to left relative to the vaccinia genome.

The recombinant vaccinia virus, vP425 (184), was identified on the basis of blue plaque formation in the presence of the chromogenic substrate, X-gal, as described by others (9,24). Substitution of the Beta-galactosidase gene by yet another foreign gene in subsequent vaccinia recombinants could be readily scored by isolating colorless plaques instead of blue plaques.

To facilitate future cloning steps, the Smal site derived from the pUC8 multicloning region was eliminated by digestion of pSD466VC with BamHI/EcoRI, blunt ending with the Klenow fragment of E. coli polymerase, and religation. Thus, the single Smal site remaining in the resulting plasmid, pSD467VC, is in the polylinker region of the HA deletion.

Identification of DNA sequences encoding EHV-l gp13 gene. The DNA sequence encoding the glycoprotein EHV-1 gp13 resides in the 7.3 Kb BamHI-H fragment of EHV-1 (3). Nucleotide sequence data for both strands was obtained from the pUC (BamHI-H) region utilizing overlapping subclones using the modified T7 enzyme SEQUENASE (40) (U.S.

Biochemicals, Cleveland, OH). Standard dideoxy chain- termination reactions (33) were performed on double stranded plasmid templates that had been denatured in alkali. The M13 forward and reverse primers were used to obtain the initial sequence of each clone. Custom 16-17-mer primers, synthesized using standard chemistries (Biosearch 8700, San Rafael, CA; Applied Biosystems 380B, Foster City, CA), were used to walk along the remaining fragment. The IBI Pustell sequence analysis program was used in all sequence data analysis (29).

DNA sequence analysis revealed an open reading frame of 1,404 bp encoding 468 amino acids with a predicted primary translation product of 50.9 kDa. Significant amino acid homology in the carboxy half of the putative gp13 open reading frame was observed to gC of herpes simplex viruses type l and type 2, gill of pseudorabies virus, and gpV of varicella-zoster virus suggesting that gp13 was a member of the gC like glycoproteins of herpesviruses. Further detailed analysis of the EHV-1 gp13 open reading frame was presented in a previous publication (2). To facilitate the description of the cloning and expression of the EHV-1 gp13 in vaccinia virus vectors, the gp13 open reading frame plus additional 5' and 3' sequences are shown in FIG. 2. In FIG. 2, a presumptive TATA box and amino acids comprising

putative signals and membrane anchor elements are

underlined. The potential cleavage site of the signal sequence is noted with an arrow following the cleavage signal ASA (open circles). Potentially, nine N-linked glycosylation sites exist within the signal and anchor sequences as defined by the Asn-X-Ser/Thr motif (asterisks).

Cloning of the EHV-1 gp13 gene into a vaccinia virus donor plasmid. An early/late vaccinia virus promoter, H6, has been used for the expression of foreign genes in fowlpox virus vectors (41,42). This promoter element corresponds to the DNA sequences immediately upstream of the H6 open reading frame in vaccinia Hindlll-H fragment (31).

Referring now to FIG. 3, to mutate and insert the

H6 promoter into pSD467VC, oligonucleotides H6SYN oligos A-D were synthesized. The sequence of H6SYN oligos A-D, with modified base as underlined and restriction sites as

indicated, is as follows:

Bglll

5'-GATCTCTTTATTCTATACTTAAAAAGTGAAAATAAATACAAAGGTTCTTGAGGGTT 3' -AGAAATAAGATATGAATTTTTCACTTTTATTTATGTTTCCAAGAACTCCCAA

GTGTTAAATTGAAAGCGAGAAATAATCATAAATTATTTCATTATCGCGATATCCGTTAA CACAATTTAACTTTCGCTCTTTATTAGTATTTAATAAAGTAATAGCGCTATAGGCAATT

GTTTGTATCGTACCC-3'

CAAACATAGCATGGG-5'

Smal

The underlined bases denote modification from the native H6 promoter sequence.

The 130 bp full length, double stranded DNA formed by the annealing of H6SYN oligos A-D was purified by

electroelution from an agarose gel and ligated to 0.5 Kb

Smal/Hindlll and 3.1 Kb Bglll/Hindlll fragments derived from pSD467VC. The resulting plasmid, pTP15 (184), has the ATG initiation codon modified to CCC as part of the Smal site which is immediately followed by a PstI site. An Nsil linker, 5'-TGCATGCATGCA-3', (New England Biolabs, Beverly, MA) was inserted into the Smal site of pTP15 to generate the plasmid pNSI.

An EHV-1 EcoRI/Narl fragment in which the EcoRI site is 120 bp upstream of the ATG initiation codon and where the Narl site is 23 bp upstream from the TAG

termination codon of EHV-1 gp13 was cloned into phage

M13mpl9 generating the recombinant phage M13EcoRNar. Using oligonucleotide-directed mutagenesis (17) an Nsil site was introduced by changing the sequence TTGCCT (bases 130-135 in FIG. 2) in the EHV-1 gp13 gene to ATGCAT. The EcoRI/Narl fragment from mutant phage M13EcoRNar was cloned into pUC8 at EcoRI/Narl sites generating plasmid pNSIEN.

Two 42-mer oligonucleotides were synthesized having the sequence, with restriction sites as indicated, as follows:

Narl gp13 3'end Ndel

5'-CGCCGTACAAGAAGTCTGACTTTTAGATTTTTATCTGCAGCA-3'

3' -GGCATGTTCTTCAGACTGAAAATCTAAAAATAGACGTCGTAT-5'

PstI

In this oligonucleotide, the termination codon (TAG) is immediately followed by a vaccinia early transcription terminator (ATTTTTAT). The double stranded DNA fragment obtained by annealing the pair of 42-mers contains an Narl sticky end, followed by the 3' end of the coding sequence for the EHV-1 gp13 gene, as well as a vaccinia early transcription termination signal (45), a PstI site, and an Ndel sticky end. This fragment was inserted between the Narl/Ndel sites of pNSIEN generating pNSIENPN (FIG. 3).

The Nsil/PstI fragment from pNSIENPN was isolated and cloned into the Nsil/PstI sites of plasmid pNSI, generating plasmid pVHA6g13Nsil (FIG. 3). pVHA6gl3NsiI was cut at the EcoRV site in the H6 promoter and the Nsil site which had been introduced near the beginning of the EHV-1 gp13 gene. This vector fragment was blunt ended with Mung Bean nuclease. Two complementary 32-mer oligonucleotides were synthesized having the sequence, with restriction site as indicated, as follows: ECORV

5'-ATCCGTTAAGTTTGTATCGTAATGTGGTTGCC-3'

3'-TAGGCAATTCAAACATAGCATTACACCAACGG-5'

H6 promoter gp13 5' end

These oligonucleotides were annealed and ligated into the pVHA6g13NsiI vector fragment, producing plasmid pVHA6g13, which contains a precise junction at the ATG initiation codon (underlined in the 32-mer sequence) of the H6 promoter and EHV-1 gp13 gene (FIG. 3).

pVHA6g13 was transfected into vP425 infected cells to generate the vaccinia recombinant vP483 containing the EHV-1 gp13 gene (FIG. 3).

Construction of vaccinia virus recombinants.

Procedures for transfection of recombinant donor plasmids into tissue culture cells infected with a rescuing vaccinia virus and identification of recombinants by in situ

hybridization on nitrocellulose filters were as previously described (25,28). To construct vP425 where the E. coli

Beta-galactosidase gene replaces the vaccinia HA coding sequences, plasmid DNA (25ug of pSD466VCBGA in HeBS (16)) was electroporated (BioRad Gene Pulser, capacitance 960, 200 volts) into VERO cells. Subσonfluent monolayers of cells were infected at 10 pfu/cell with vP410 one hour prior to use. The infected cells were harvested with trypsin and washed with HeBS before electroporation. Cells were

incubated in MEM + 5% fetal bovine serum at 37°C for 24 hours, harvested and progeny virus plated on VERO

monolayers. Recombinant virus expressing Beta-galactosidase was detected as blue plaques in the presence of X-gal substrate (9,24). To generate recombinant vaccinia virus where the EHV-1 gp13 gene replaced the Beta-galactosidase gene in vP425, a similar protocol was followed except that the donor plasmid was pVHA6g13 and rescuing virus was vP425. The vaccinia recombinant vP483, containing EHV-1 gp13 was detected as a colorless plaque in the presence of X-gal and confirmed as a true recombinant by DNA hybridization after 3 cycles of plaque purification.

Expression of the EHV-1 gp13 gene on the surface of cells infected with the recombinant vaccinia virus vP483. BSC-40 cells were seeded on 22mm glass coverslips in 35mm dishes at 5 x 10⁵ cells/dish. At approximately 80%

confluency the cells were infected at 2 pfu/cell. After a 1 hour adsorption period the virus inoculum was removed and MEM plus 2% fetal bovine serum added. At 20 hours post infection the coverslips were washed with phosphate buffered saline (PBS) containing 0.2% BSA and 0.1% NaN3 (PBS+) and exposed to 0.1ml of anti-gp13 monoclonal antibody, 14H7 (3) diluted one to a thousand in PBS+. After 1 hour in a humidified chamber at room temperature the cells were washed 3 times in PBS+. This procedure was repeated with

fluorescein isothiocyanate-conjugated goat anti-mouse IgG. Finally, the cells were fixed for 20 minutes in 2%

paraformaldehyde in PBS. The coverslips were mounted in 80% glycerol in PBS containing 3% n-propyl gallate and

fluorescence was observed with a microscope.

The protein predicted from the DNA sequence has the typical features characteristic of a membrane spanning glycoprotein (14). In a productive EHV-1 infection that gp13 glycoprotein is incorporated into the various membrane systems of the cell and is transported into the cytoplasmic membrane and detectable on the external surface of the infected cell. EHV-1 gp13 is additionally a component of the EHV-1 virion. Therefore, immunofluorescence studies were performed to determine whether EHV-1 gp13 expressed by the vaccinia virus recombinant, vP483, was similarly

presented on the cytoplasmic membrane of infected cells.

Anti-gp13 specific monoclonal antibody followed by

fluorescein-conjugated goat anti-mouse IgG revealed a strong membrane immunofluorescence in vP483 infected cells but not in vaccinia virus vP410 infected cells. This suggests that the EHV-1 gp13 expressed by the recombinant vaccinia virus vP483 is presented on the cytoplasmic membrane as expected for authentic synthesis of a membrane spanning glycoprotein.

Immunoprecipitation of EHV-1 gp13 products

synthesized from recombinant vaccinia virus vP483 infected cells. Two million cells forming a confluent monolayer in a 60mm dish were infected at 10 pfu/cell. The inoculation was performed in methionine-free medium. After the adsorption period, the inoculum was removed and 2ml of methionine-free medium containing 20 μ Ci/ml of ³⁵S-methionine added. The infection was allowed to proceed for 24 hours when cells were lysed by the addition of 1ml of 3x Buffer A containing 3% NP-40, 30 mM Tris pH 7.4, 450 mM NaCl, 3 mM EDTA, 0.03% sodium azide, and 0.6mg/ml PMSF. The lysed cells and supernatant were harvested, vortexed, and clarified by centrifugation at 10,000g for 15 minutes.

Protein A-Sepharose CL-4B (Pharmacia, Cat. No.

17.0780.01) was prepared as a 1:1 slurry in IX Buffer A. A rat anti-mouse conjugate (Boehringer Mannheim, Cat. No. 605 500) was diluted to 1:100 in the slurry and bound to the beads at room temperature for 4 hours with rocking. The beads were then washed thoroughly with 6 one ml washes in

Buffer A to remove unbound conjugate. A monoclonal antibody specific to gp13 was then bound to the beads at room

temperature for 4 hours. Excess antibody was removed by thorough washing. One ml of clarified infected cell lysate was precleared by incubation with Protein A-Sepharose beads to which normal mouse serum had been bound. These beads were removed by centrifugation. One ml of the clarified precleared lysate was then mixed with 100ul of the beads to which the specific monoclonal antibody had been bound. This mixture was rocked at room temperature for 4 hours. The beads were then removed by centrifugation and washed

thoroughly by four washes in IX Buffer A and two washes in 10 mM Tris pH 7.4 containing 0.2M LiCl and 2M urea. The antibody-antigen complex was then removed from the beads and disrupted by the addition of 50ul of 2x Laemmli Disrupting Solution (60,195). The sample was then boiled for 5 min before electrophoresis.

There are two products of approximately 44 and 47 kDa detectable which are somewhat smaller than the predicted primary translation product (51 kDa) and a larger product of approxi-mately 90 kDa which is consistent with a fully glycosylated form of the EHV-1 gp13 gene product. No equivalent polypeptides were precipitated from control vaccinia virus infected cells. ExamPle 2 - CONSTRUCTION OF VACCINIA VIRUS RECOMBINANTS EXPRESSING THE EQUINE HERPESVIRUS gp14 GLYCOPROTEIN

Replacement of the M2L gene in vaccinia virus by the E. coli Beta-galactosidase gene.

In order to insert the EHV-1 gp14 coding sequences into a vaccinia virus vector , a recombinant vaccinia virus , vP458, expressing the E. coli LacZ gene was constructed.

Substitution of the LacZ coding sequences in the recombinant virus, vP458, with sequences encoding EHV-1 gp14 allows a blue to colorless plaque screening system for identifying EHV-1 gp14 containing recombinant viruses (9,24) in the presence of X-gal, a chromogenic Beta-galactosidase

substrate. Furthermore, with the intention of constructing vaccinia virus recombinants expressing both EHV-1 gpi4 and EH-1 gp13, an insertion locus for EHV-1 gp14 unique from the hemagglutinin deleted locus used for the insertion of EHV-1 gp13 in Example 1 was prepared at the M2L locus of Hindlll M. The entire coding sequence of the M2L gene in the vaccinia Hindlll M fragment was eliminated and replaced with the E. coli LacZ gene encoding Beta-galactosidase. The cloning steps for the construction of vP458 are

schematically presented in FIG. 4.

Referring now to FIG. 4, an open reading frame reading right to left relative to the vaccinia genome and encoding a putative protein of 220 amino acids is located entirely within the Hindlll M fragment from the Copenhagen strain of vaccinia virus to the left of the unique Bglll site. According to convention (31), this gene, which is located immediately to the right of MIL (58), was designated M2L. Deletion studies directed to the vaccinia (WR) genome extending leftward from the unique Bglll site in Hindlll fragment M (57) indicate that vaccinia coding sequences contained in Hindlll M to the left of the Bglll site are not essential for replication of the virus in tissue culture.

To facilitate use of the M2L region as an insertion locus for foreign genes, a plasmid vector,

pMP409DVC, was created in which the entire M2L coding sequence was replaced by a Bglll site as follows. pSD409VC, which consists of the Copenhagen vaccinia Hindlll M fragment cloned into the Hindlll site of pUC8, was digested with

BamHI/Bglll and self-ligated, thus removing the right end of Hindlll M and destroying the Bglll site. The resulting plasmid, pMP409BVC, was linearized with SphI, which cuts within the M2L open reading frame, and was subjected to Bal- 31 exonuclease digestion for two minutes. Mutagenesis was performed on the resulting DNA (19) using a synthetic 49 mer (5'-TTTCTGTATATTTGCAACAATTTAGATCTTACTCAAAATATGTAACAAT-3'; Bglll site underlined). In the mutagenized plasmid,

pMP409DVC, the M2L coding sequences have been deleted from position +3 through the end of the open reading frame. The G of the initiation codon ATG was changed to a C to create a unique Bglll site (AGATCT) at the deletion junction.

A 3.2 Kb Bglll/BamHI partial fragment containing

3.1 Kb of the E. coli Beta-galactosidase gene between the BamHI sites of pMC1871 (34) under the transcriptional control of the 0.1 Kb vaccinia 11 kDa late promoter (7) was cloned into the unique Bglll site of pMP409DVC. A

recombinant plasmid containing the 11 kDa promoter/Beta- galactosidase gene cassette in a right to left orientation relative to flanking vaccinia arms and genome was designated pMP409DVCBG. pMP409DVCBG was used as donor plasmid for recombination with rescuing vaccinia virus, vP410, described in Example 1. The novel vaccinia recombinant, designated vP458, expressing the Beta-galactosidase gene inserted into the M2L deletion locus was detected using the chromogenic X- gal substrate (9,24) and purified by repeated plaque

cloning.

Cloning of the EHV-1 gp14 gene. Referring now to

FIG. 5, the EHV-1 gp14 coding sequence spans the junction between the BamHI restriction fragments a and i (3). The EHV-1 DNA fragments BamHI-a (21.3 Kb) and i (7.1 Kb) (59) were isolated from agarose gels. Plasmid pUC (BamHI-i) was constructed by inserting the EHV-1 BamHI-i fragment into plasmid pUC8 at the BamHI site. The EHV-1 BamHI-a fragment was digested with EcoRI and ligated into EcoRI/BamHI

digested pUC8. Plasmid pUC (BamHI-a/EcoRI) contains a 10 Kb EHV-1 BamHI/EcoRI insert. Based on the fragment size determinations reported (59), DNA sequences in this insert are contiguous with those of the BamHI-i fragment in the EHV-1 genome.

Nucleotide sequence analysis. Nucleotide sequence analysis was obtained utilizing different subclones from the pUC (BamHI-a/EcoRI) and pUC (BamHI-i) plasmids. Sequencing of the plasmid pUC (BamHI-a/EcoRI) was started at the BamHI site because the EHV-1 gp14 gene spans the BamHI-a/i

junction (3). The orientation of the pUC (BamHI-i) plasmid was determined by restriction enzyme digestion. Since the EHV-1 BamHI terminus closest to the EcoRI site in pUC

(BamHI-i) was found to be the BamHI site at the BamHI-a/i junction, sequencing of the fragment was initiated from this BamHI end.

Sequence data for both strands was obtained as described in Example 1. The nucleotide sequence of the 3,351 bp fragment containing the EHV-1 gp14 coding sequence is shown in FIG. 6. Numbering in the left and right hand margins pertains to the amino acid and nucleic acid

sequence, respectively. The putative CAT and TATA boxes are underlined. Amino acids in the signal and membrane spanning region are also underlined with the arrow indicating a potential signal peptide cleavage site. The thirteen potential glycosylation sites using the consensus sequence (Asn-X-Ser/Thr) are indicated by an asterisk.

DNA sequence analysis revealed an open reading frame extending from nucleotide positions 300 to 3239 reading from left to right relative to the EHV-1 genome, i.e. the ATG start codon was contained in the BamHI-a/EcoRI fragment and the stop codon TAA was contained in the BamHI-i fragment (3,59).

Putative transcriptional regulatory signals were found in the region 5' to the ATG initiation codon at position 300. A TATA box having the sequence AAATATAT

(nucleotides 148 to 155) was located 70 nucleotides

downstream from a putative CAT box at positions 71 to 77 having the sequence GGTCAAT. A polyadenylation signal AATAAA (nucleotides 3251 to 3256) was located 8 nucleotides downstream from the TAA termination codon (nucleotides 3240 to 3242). Nine out of eleven nucleotides in the sequence 5'-TCCTGCGCGCA-3' (nucleotides 218 to 228) are complementary to the 18S ribosomal RNA sequence 3'-AGGAAGGCGT-5' (61) and may serve as the ribosome binding site.

Analysis of the EHV-1 gp14 structure. The EHV-1 gp14 open reading frame encodes 980 amino acids with a calculated molecular weight of 109.8 kDa. Analysis of the amino acid sequence revealed a number of features common to membrane-associated glycoproteins. A region extending from amino acids 58 to 99 had a characteristic hydrophobicity profile and is proposed to be the signal sequence (FIG. 6). An unusual feature of the EHV-1 gp14 gene product is that the long hydrophobic signal sequence is preceded by a long hydrophilic sequence. This characteristic has also been noted for the pseudorabies virus (PRV) gll (62) and for the bovine herpesvirus 1 (BHV-1) gl gene (63), both of which are also HSV gB homologs. A hydrophobic region consisting of 45 amino acids (amino acids 826 to 870) is predicted to

function as a transmembrane anchor domain. The hydrophilic cytoplasmic domain contains 110 amino acids.

There are eleven Asn-X-Thr/Ser (where X can be any amino acid except proline) sites for potential N-linked glycosylation (64). An unusual feature is that there are also two potential glycosylation sites in the cytoplasmic domain (FIG. 6).

A hydrophilicity plot of the EHV-1 gp14 coding sequence is shown in FIG. 7. The hydropathic index of EHV-1 gp14 is computed by the method of Kyte and Doolittle (65) with a window of seven amino acids and no smoothing. Points below the horizontal line represent areas of higher

hydrophobicity, therefore indicating potential signal and/or membrane spanning regions. The characteristics of a

membrane spanning glycoprotein including signal and anchor elements and the long hydrophilic region preceding the signal sequence are found for the EHV-1 gp14 coding

sequence.

Localization of the antigenic determinant recognized by the anti-EHV-1 gp14 monoclonal antibody, 3F6. Lambda gt11 expression vectors and monoclonal antibodies have been useful in identifying the EHV-1 DNA sequences encoding the major EHV-1 glycoproteins (3). A lambda gt11 recombinant, 4a1, was shown to express an EHV-1 gp14 epitope recognized by the specific monoclonal antibody 3F6 (3). In order to determine the identity of this epitope, the EHV-1 DNA contained within 4al was sequenced and compared with the DNA sequence of the EHV-1 gp14 coding sequence (FIG. 6). To sequence the DNA fragment corresponding to the EHV-1 gp14 epitope in the lambda gtll recombinant 4al recognized by anti-EHV-1 gp14 monoclonal 3F6 (3), 4al was digested with EcoRI, the EHV-1 fragment isolated on agarose gels and ligated into the EcoRI site of pUC8. DNA sequencing was performed as described above with the M13 universal forward and reverse primers.

The nucleotide sequence alignment indicated that this epitope was contained within the 66 amino acid region corresponding to 107 (Thr) through 172 (Val) of the deduced primary translation product. The epitope is therefore located within the amino-terminal region of the deduced EHV- 1 gp14 surface domain.

Comparison of the EHV-1 gp14 amino acid sequence to other herpesvirus glycoproteins. Comparison of the amino acid composition of the EHV-1 gp14 gene revealed extensive homology with glycoproteins of other herpesviruses. Thus, the EHV-1 gp14 is homologous to gll of PRV (62), gl of BHV-1 (63), gll of varicella-zoster virus (VZV) (66), gB of herpes simplex virus (HSV) (67,71,72) as well as to glycoproteins in Epstein-Barr virus (EBV) (68) and human cytomegalovirus (HCMV) (10).

Oligonucleotide-directed mutagenesis of the 5' terminus of the EHV-1 gp14 coding sequence. Referring now again to FIG. 5, plasmid Blue (Kpnl/BamHI) was generated by inserting a Kpnl/BamHI fragment from pUC (BamHI-a/EcoRI) into plasmid Bluescript SK+ digested with Kpnl/BamHI.

Oligonucleotide directed mutagenesis was performed by a modification of the procedure of Kunkel (17) using uracil- containing DNA templates from plasmid Blue (Kpnl/BamHI) produced in the dut- ung- host E. coli strain CJ236. In the mutagenized plasmid an Nsil site was created at codons 1 and 2 of the EHV-1 gp14 gene, changing the sequence ATG/TCC (Met/Ser) to ATG/CAT (Met/His). The mutated sequence was verified by DNA sequence analysis. The Kpnl/BamHI fragment from the mutant was transferred to Kpnl/BamHI digested pUC18 generating the plasmid pUC (Kpnl/BamHI).

A plasmid, pUCg14, containing the complete EHV-1 gp14 gene with the Nsil site mutation was constructed by inserting theEcoRI /BamHI fragment from pUC (Kpnl/BamHI) into EcoRI/BamHI digested pUC (BamHI/PstI), a 3.9 Kb

subclone of pUC (BamHI-i).

Construction of chimeric donor plasmid pVM2LH6g14. pMP409DVC was cut with Bglll and ligated with synthetic double-stranded DNA containing the modified vaccinia H6 (early/late) promoter, described in Example 1, flanked by restriction sites. Restriction sites for Nsil, SacI, PstI and EcoRI were created immediately downstream from the endogenous initiation codon in the H6 promoter. In pMG11, the polylinker sequence downstream from the H6 promoter is ATG CAT GAG CTC TGC AGA ATT CGG ATC T. The unique Nsil site, containing the H6 initiation codon (underlined), is immediately followed by unique SacI, PstI and EcoRI sites.

The EcoRI/Nsil DNA fragment from pUCg14 containing the EHV-1 DNA region upstream from the EHV-1 gp14 initiation codon was replaced by the EcoRI/Nsil fragment from plasmid pMGll, thus generating plasmid pMRHg14 which contains the right arm of vaccinia Hindlll M, the H6 promoter, and the entire length of the EHV-1 gp14 gene. The Hpal/PstI EHV-1 gp14 containing fragment from plasmid pMRHg14 was

transferred to the vector plasmid pMGll cut with Hpal/PstI, creating plasmid pVM2LH6g14. pVM2LH6g14 contains the entire EHV-1 gp14 coding sequence (with codon 2 changed from TCC (Ser) to CAT (His) as indicated, and approximately 1.2 Kb of EHV-1 DNA downstream from the EHV-1 gp14 gene) under the control of the H6 promoter, inserted in a right to left orientation with respect to flanking vaccinia sequences relative to the vaccinia genome targeting the insertion of the EHV-1 gp14 gene to the M2L locus.

Recombination was performed using vP458 as

rescuing virus and pVM2LH6g14 as donor plasmid. Colorless plaques were picked and analyzed for the presence of EHV-1 gp14 coding sequences using a specific EHV-1 gp14 probe labeled with ³²P. After repeated plaque cloning the

vaccinia recombinant was designated vP577.

Truncation of the EHV-1 gp14 hydrophilic leader sequences. Using variations of the mutagenesis and cloning manipulations described above, chimeric donor plasmid pVM2LH6g14-1 was constructed. To create pVM2LH6g14-1, which contains a deletion of codons 2 through 34 of EHV-1 gp14 with the substitution of 4 codons, in vitro mutagenesis (17) was performed on plasmid Blue (Kpnl/BamHI), creating an Nsil site in codons 32 through 34 rather than codons 1 and 2.

The Nsil/BamHI fragment from the newly mutagenized Blue (Kpnl/BamHI) plasmid was substituted for the Nsil/BamHI fragment in pVM2LH6gl4. Multiple Nsil linkers (New England BioLabs, Beverly, MA) were ligated into the Nsil site to bring the initial ATG in frame with the remainder of the EHV-1 gp14 coding sequence. The final plasmid, pVM2LH6g14- 1, contains the sequence ATG/CAT/GCA/TGC/ATT/GCT....

encoding Met/His/Ala/Cys/Ile/Ala....where GCT (Ala) is codon 35 of EHV-1 gp14. The remainder of pVM2LH6g14-1 is

identical to that in pVM2LH6g14.

The vaccinia recombinant vP613 was obtained by recombination with rescuing virus vP458 and donor plasmid pVM2LH6g14-1.

Example 3 - CONSTRUCTION OF VACCINIA VIRUS RECOMBINANTS

vP633 AND vP634 EXPRESSING EACH OF THE EQUINE HERPESVIRUS gp13 AND gp14 GLYCOPROTEINS

In order to construct vaccinia recombinants expressing both gp13 and gp14 EHV-1 glycoproteins,

recombination was performed with either vP577 or vP613 as rescuing virus and the donor plasmid pVHA6gl3 (described in Example 1) which contains the EHV-1 gp13 gene under the control of the vaccinia H6 promoter inserted at the HA deletion locus of vaccinia. Insertion of the EHV-1 gp13 sequences into recombinant viruses was identified by in situ DNA hybridization (25,28). Recombination of pVHA6gl3 with vaccinia virus recombinant vP577 (containing full length EHV-1 gp14) generated the double vaccinia virus recombinant vP633; recombination with vP613 (containing truncated EHV-1 gp14) generated the double vaccinia recombinant vP634. The vaccinia virus double recombinants vP633 and vP634 were plaque cloned and the presence of both EHV-1 gp13 and gp14 coding sequences confirmed by DNA hybridization analysis and by expression assays (see below).

Immunoprecipitation of EHV-1 gp13 and gp14

glycoproteins expressed in vaccinia virus recombinants. In order to assess the EHV-1 gp13 and gp14 glycoproteins expressed by vaccinia virus recombinants, VERO cells were infected with the recombinants and proteins were

metabolically labeled with ³⁵S-methionine and

immunoprecipitated as described in Example 1. The specific monoclonal antibody to EHV-1 gp13 (14H7) or to EHV-1 gp14 (3F6) (3) were bound at a 1:1000 dilution for 4 hours at room temperature. Samples were analyzed by SDS

polyacrylamide gel electrophoresis on a 10% polymer gel at 30mA (constant current) for approximately 6 hours.

Autoradiograms were prepared.

No significant products were immunoprecipitated by the specific anti-EHV-1 gp13 monoclonal 14H7 (3) or by the specific anti-EHV-1 gp14 monoclonal 3F6 (3) from either uninfeσted VERO cells or VERO cells infected with the control hemagglutinin minus vaccinia virus, vP452 (184). EHV-1 gp13 radiolabeled products were precipitated by monoclonal 14H7 from VERO cells infected with vP483, a vaccinia recombinant expressing only the EHV-1 gp13, or the vaccinia virus double recombinants expressing both EHV-1 gp13 with either intact gp14, vP633, or truncated gp14, vP634. There are two products of approximately 44 and 47 kDa detectable which are somewhat smaller than the predicted primary translation product (51 kDa) and a larger product of approximately 90 kDa which is consistent with a fully glycosylated form of the EHV-1 gp13 gene product.

Significantly, the quality and quantity of expression of EHV-1 gp13 is unaffected by coexpression of either form of EHV-1 gp14 in the vaccinia double recombinants, vP633 and vP634. VERO cells were infected with vP633, vP634, vP613, and vP577, respectively, and immunoprecipitated with the specific anti-EHV-1 gp14 monoclonal 3F6 (3). With vP633 (containing full length gp14 plus gp13) and with vP577

(containing full length gp14), major bands at approximately 34, 47, 60-64 and 90 kDa were observed; whereas with vP634 (containing truncated gp14 plus gp13) and with vP613

(containing truncated gp14), major bands at 34, 47, 57, 72- 82 and 116 kDa were observed. Again no significant

differences in the synthesis of EHV-1 gp14 of either form is observed during coexpression with EHV-1 gp13.

Immunofluorescence analysis of EHV-1 gp13 and gp14 products synthesized by recombinant vaccinia viruses.

Immunofluorescence of recombinant vaccinia virus infected VERO cells was performed as described in Example 1 using either EHV-1 gp13 or gp14 specific monoclonal antibody.

EHV-1 gp13 was readily detectable on the surface of VERO cells infected with vaccinia recombinants vP483, vP633 and vP634 as well as internally after acetone

fixation. No significant internal or surface

immunoreactivity toward gp13-specific antibody was seen in vP410, vP577 or vP613 infected cells. Expression of EHV-1 gp14 was readily detectable in acetone fixed VERO cells infected with vaccinia recombinants vP577, vP613, vP633 and vP634. No significant internal immunofluorescence toward gp14-specific antibody was seen in vP410 or vP483 infected cells. Using gp14-specific monoclonal antibody, 3F6, a weak surface immunofluorescence was observed in cells infected with vP613 or vP634, which express the truncated form of EHV-1 gp14 and no significant surface response above control viruses vP410 and vP483 was obtained with recombinant vaccinia viruses vP577 and vP633 which express the full length EHV-1 gp14 gene (see also Example 8).

Example 4 - IMMUNIZATION OF GUINEA PIGS WITH THE VACCINIA

RECOMBINANT vP483

In order to determine the immunogenicity of the gp13 equine herpes virus gene product expressed by the vaccinia recombinant vP483, guinea pigs were inoculated with the virus and the presence of serum neutralizing antibodies against both vaccinia virus and equine herpes virus was assayed.

Fifteen guinea pigs weighing approximately 450 grams were divided into groups of five. One group received 1ml of the vaccinia recombinant (10⁸TCID₅₀/ml) on day 0 followed by a 1ml booster on day 21 by subcutaneous

inoculation. The second group received similar inoculations but with vaccinia vP452 (10⁸TCID₅₀/ml). The third group remained unvaccinated. All the guinea pigs were bled prior to the primary vaccination and on days 21 and 35. Sera were prepared and tested for the presence of neutralizing

antibodies to both vaccinia and EHV-1 (strain Kentucky) using 50 TCID₅₀ of virus assayed on swine testicular cells.

As shown in Table 1, the EHV-1 gp13 vaccinia recombinant vP483 elicits an obvious seroconversion in guinea pigs. Serum neutralizing titers obtained with vaccinia virus are shown in parenthesis in Table 1. Both vaccinia and EHV-1 serum neutralizing antibodies are

detectable 21 days after the primary inoculation and a significant increase in the titer of serum neutralizing antibodies is obtained by 2 weeks after a second inoculation of virus on day 21. It should be noted that the serum vaccinia neutralizing titers obtained in guinea pigs

inoculated with the recombinant virus expressing EHV-1 gp13 are significantly higher (t=7.2) than the titers obtained from guinea pigs inoculated with the vaccinia vP452 virus.

Table 1. Serum neutralizing antibodies present in guinea pigs inoculated with either a vaccinia recombinant expressing EHV-1 gp13 or a control vaccinia virus, vP452.

Example 5 - IMMUNIZATION OF GUINEA PIGS WITH THE VACCINIA RECOMBINANT vP577 AND vP613

Guinea pigs were immunized to evaluate their response against EHV-1 gp14 expressed by vaccinia

recombinants vP577 and vP613. Guinea pigs weighing

approximately 450 g received 10⁵ TCID₅₀ of either vP577 or vP613 vaccinia recombinant by the subcutaneous route, one ml on each of day 0 and day 21. Guinea pigs were bled on days 0, 21 and 35, sera prepared and assayed for EHV-1

antibodies. Neutralization tests were performed on swine testicular cells against 50 TCID₅₀ of EHV-1 virus, strain Kentucky. Vaccinia antibodies were titrated by ELISA using an anti IgG (H&L) peroxidase conjugate.

The results are shown in Table 2. No serum neutralizing activity against EHV-1 was obtained in guinea pigs immunized with the vaccinia recombinant, vP577,

containing the full length EHV-1 gp14 gene (data not shown). On the other hand, guinea pigs inoculated with the

recombinant vaccinia virus, vP613, expressing a truncated EHV-1 gp14 gene induced similar levels of EHV-1 serum neutralizing antibodies (Table 2) as did the vaccinia recombinant, vP483, expressing EHV-1 gp13 (Table 1).

Although EHV-1 serum neutralizing antibodies are detectable at three weeks after the primary vaccination, a more

significant level is observed two weeks after the secondary immunization (Table 2). In all immunized animals, responses were obtained when vaccinia antibodies were assayed by

ELISA.

Table 2. Serum neutralizing antibodies present in guinea pigs inoculated with a vaccinia recombinant expressing EHV-1 gp14.

Example 6 - PROTECTION OF VACCINATED HAMSTERS FROM CHALLENGE WITH EHV-1

In order to assess the efficacy of the vaccinia recombinant vP483 expressing EHV-1 gp13, hamsters were given either a primary or primary plus booster vaccination and they, along with an uninoculated control group or a group inoculated twice with a control vaccinia virus, vP452, were challenged intraperitoneally with a hamster adapted Kentucky strain of

EHV-1.

Forty syrian hamsters (forty day old weighing between 55 and 65g) were separated into four groups. Group A received a single subcutaneous (1ml) inoculation of either 10⁸, 10⁶, or 10⁴ TCID₅₀ of the vaccinia recombinant vP483, five animals per dose. Group B was vaccinated with vP483 on day 0 followed by a booster on day 14. The (1ml) primary and booster doses were administered subcutaneously to groups of 5 animals using 10⁸, 10⁶, or 10⁴ TCID₅₀. Group C consisted of 5 hamsters and received 2 subcutaneous injections (10⁸ TCID₅₀ per injection) on days 0 and 14 of vaccinia vP452.

Five hamsters in group D were left as unvaccinated controls. All the hamsters received 200 LD₅₀ of a hamster adapted

Kentucky strain of EHV-1 by the intraperitoneal route 14 days after the last immunization. Survivors were counted 7 days after challenge.

The results are shown in Table 3. All

unvaccinated and vaccinia vP452 virus vaccinated hamsters died within 5 days of

Table 3. Protection of hamsters vaccinated with the vaccinia recombinant, expressing EHV-1 gp13, against EHV-1 challenge.

challenge. Significant levels of protection against EHV-1 challenge were observed in hamsters vaccinated with the vaccinia recombinant vP483 expressing EHV-1 gp13. No significant differences in protection levels were observed in hamsters immunized with either primary or primary plus booster doses. The protective dose (PD₅₀) was similar PD₅₀ = 6.32 log₁₀ primary and 6.12 log₁₀ primary plus booster.

Nevertheless, 100% protection was only observed in the group receiving two doses of 10⁸ TCID₅₀ recombinant virus.

In order to determine the protective efficacy of a vaccinia virus recombinant expressing EHV-1 gp14 alone or in combination with EHV-1 gp13, challenge studies were

performed on vaccinated hamsters. Twenty one-day-old syrian hamsters weighing approximately 60 g each were inoculated subcutaneously with 1 ml of control vaccinia virus or with recombinant vaccinia viruses vP483, vP577, vP613, vP633 and vP634 expressing EHV-1 gp13 and/or gp14. Primary

vaccination was followed by an identical vaccinating dose (pfu/ml (log₁₀)) on day 14. All hamsters, including non- inoculated controls, were challenged 14 days after the last immunization with an intraperitoneal injection of 200 LD₅₀ of EHV-1 hamster adapted Kentucky strain. Survivors from groups of five were calculated 14 days post-challenge at which point the experiment was terminated. The dose of inoculum giving 50% protection of the hamsters is evaluated as log₁₀ TCID₅₀/ml inoculant.

As shown in Table 4, the vaccinia virus recombinant, vP577, expressing the full length EHV-1 gp14 gene failed to protect hamsters against challenge with a PD₅₀ calculated > 9.0 log₁₀. On the other hand, the

truncated EHV-1 gp14 gene as expressed by the vaccinia recombinant, vP613, gave good protection on challenge (Table 4). The calculated PD₅₀ is somewhat better (5.2) than that obtained with the EHV-1 gp13 expressing vaccinia

recombinant, vP483 (6.1). Surprisingly, the coexpression of EHV-1 gp13 and gp14, whether the full length gp14 gene or the truncated gp14 gene in vaccinia virus recombinants vP633 and vP634, respectively, gave significantly enhanced

protective efficacy compared with efficacy for the EHV-1 glycoproteins expressed singly. Hence, the amount of virus inoculum to achieve a 50% protection of the vaccinated hamsters was significantly decreased when EHV-1 gp13 and gp14 were coexpressed in the same vaccinia virus

recombinant.

Table 4. Protection of hamsters vaccinated with the vaccinia recombinants, expressing EHV-1 gp13 and/or gp14, against EHV-1 challenge.

Example 7 - CONSTRUCTION OF AVIPOXVIRUS RECOMBINANTS

EXPRESSING THE EQUINE HERPESVIRUS gp13 GLYCOPROTEIN

Referring now to FIG. 8, pVHA6g13 was utilized as the source of the EHV-1 gp13 gene. To isolate the DNA segment containing the entire EHV-1 gp13 gene, pVHA6g13 was digested with Nrul and Hindlll. A fragment of approximately 1.8 Kb containing 28 bp of the 3' end of the vaccinia virus H6 promoter, the entire EHV-1 gp13 gene, and approximately 410 bp of vaccinia virus sequences was generated by this digestion. The 1.8 Kb Nrul/Hindlll fragment was isolated for insertion into the avipoxvirus insertion vectors pFPCV2 and pCPCVl.

The fowlpox virus (FP) insertion vector pFPCV2 provides a vehicle for generating recombinants which harbor foreign genes in a non-essential region of the FP genome designated the f7 locus. pFPCV2 was derived from pRW731.13. The plasmid pRW731.13 contains an FP genomic PvuII fragment of approximately 5.5 Kb inserted between the two PvuII sites of pUC9. Initially, a multiple cloning sequence (MCS) was ligated into the unique HincII insertion site within this 5.5 Kb PvuII FP genomic fragment. The MCS was derived by annealing oligonucleotides CE4 (5'-TCGC

GAGAATTCGAGCTCGGTACCGGGGATCCTCTGAGTCGACCTGCAGGCATGCAAGCTTGTT

-3') and CE5 (5'-

AACAAGCTTGCATGCCTGCAGGTCGACTCTTAGAGGATCCCCGGTACCGA GCTCGAATTCTCGCGA-3' ). The plasmid containing the MCS was designated as pCEll.

pFeLVIA is a derivative of vaccinia insertion vector pTP15 (184) (FIG.3) in which the feline leukemia virus (FeLV) env gene (192), is inserted into the PstI site downstream from the H6 promoter. To transfer the 2.4 kb expression cassette to a FP vector, (FIG.8) the H6/FeLV env sequences were excised from pFeLVIA by digestion with Bglll and partial digestion with PstI. The Bglll site is at the 5' border of the H6 promoter sequence. The PstI site is located 420 bp downstream from the translation termination signal for the FeLV envelope glycoprotein open reading The 2.4 Kb H6/FeLV env sequence was inserted into pCEll digested with BamHI and PstI. This plasmid was designated as pFeLVFl. The pFeLVFl plasmid was then

digested with PstI to remove the FeLV env sequences. The resultant plasmid containing the vaccinia virus H6 promoter within pCEll was designated pFPCVl. The sequences 5' to the promoter were mutagenized (19) to remove extraneous

sequences using oligonucleotide FPCV1 (5'- CAGTAATACACGTTATTGCAGAGAGGACCATTCTTTATTCTATACTTAAAAAGT-3') to produce pFPCVl. The region 3' to the promoter (multiple cloning site) was mutagenized with oligonucleotide FPCV3 (5'-TAGAGT CGACCTGCAGGCATCCAAGCTTGTTAACGAC-3' ) to remove the SphI site, which contains an ATG. The resultant plasmid was designated pFPCV2.

The 1.8 Kb Nrul/Hindlll EHV-1 gp13 fragment, defined above, was inserted into the 8.0 Kb Nrul/Hindlll fragment derived by digestion of pFPCV2. This 8.0 Kb

Nrul/Hindlll fragment contained the 5' portion of the vaccinia virus H6 promoter (100 bp), the FP flanking

sequences (4.8 Kb upstream and 1.5 Kb downstream from the insertion site) and 2.4 Kb of pUC (BRL, Bethesda, MD).

Ligation of these two fragments resulted in the formation of a 9.8 Kb plasmid designated as pFPEHV13A.

The plasmid pFPEHV13A was then digested with Kpnl and Hindlll to remove an approximately 600 bp fragment.

This fragment contained the 3' most region of the EHV-1 gp13 gene (200 bp) and the 410 bp vaccinia virus DNA segment. The 600 bp Kpnl/Hindlll fragment was replaced by a 200 bp fragment derived from pNSIENPN (FIG.3) as follows. A PstI digestion of pNSIENPN linearized the plasmid. The PstI termini were blunt-ended by the T4 DNA polymerase (New

England Biolabs, Beverly, MA) in the presence of dNTPs (0.5 mM each). Hindlll linkers (BRL, Bethesda, MD) were then ligated to the blunt-ended fragment. Following digestion with Hindlll the linearized plasmid was digested with Kpnl to yield a 200 bp fragment containing the 3' portion of the EHV-1 gp13 gene, the sequence corresponding to the

termination codon (TAG), and the TTTTTNT sequence motif known to be a vaccinia virus early transcription termination signal (45). The recombinant plasmid was designated as PFPEHV13B and was used in in vitro recombination for

insertion of the H6 promoted EHV gp13 gene into the f7 locus of the FP genome. The recombinant fowlpox virus was

designated vFP44.

Referring now to FIG. 9, pFPEHV13B was also utilized to generate a 1.4 Kb Nrul/Hindlll fragment for insertion into pCPCVl. The pCPCVl plasmid contains the vaccinia virus H6 promoter in the unique EcoRI site within the 3.3 Kb PvuII canarypox virus (CP) genomic fragment.

This insertion plasmid enables the insertion of foreign genes into the C3 locus of the CP genome. pCPCVl was derived from pRW764.2, which contains a 3.3 Kb PvuII CP genomic fragment inserted into a pUC vector. pRW764.2 was linearized by digestion withEcoRI. This fragment was blunt-ended using the Klenow fragment of the E. coli DNA polymerase (Boehringer Mannheim Biochemicals, Indianapolis, IN) in the presence of dNTPs (0.5 mM each). Vaccinia virus H6 promoter sequences and a multiple cloning region situated 3' to the promoter were excised from pFPCVl by digestion with KpnI/Hpal. This 200 bp fragment was blunt-ended with T4 DNA polymerase in the presence of dNTPs (0.5 mM each) and inserted into the linearized blunt-ended plasmid pRW764.2. The resultant plasmid was designated pCPCVl. The plasmid pCPCVl was digested with Nrul and Hindlll and the 5.8 Kb fragment was isolated for ligation to the 1.4 Kb EHV gp13 containing fragment described above. The resultant plasmid was designated pCPEHV13A. This plasmid was used in in vitro recombination experiments for insertion of the H6 promoted EHV gp13 gene into the C3 locus of the CP genome. The recombinant canarypox virus was designated VCP48.

Following the in vitro recombination, recombinant avipoxvirus containing the EHV-1 gp13 gene were identified by a standard plaque hybridization assay. Positive plaques were purified by 3 cycles of plaque isolation followed by hybridization analyses. Recombinants were designated as vFP44 and vCP48 for FP and CP recombinants, respectively. Both recombinants were analyzed using a Protein A-B- galactosidase immunoscreen assay with a monoclonal antiserum to EHV-1 gp13. The results demonstrated that CEF and VERO cell monolayers infected with either vFP44 or vCP48 express the EHV-1 gp13 on the surface of virus infected cells.

Example 8 - EVALUATION OF ADDITIONAL VACCINIA VIRUS

RECOMBINANTS EXPRESSING UNMODIFIED AND

MODIFIED VERSIONS OF THE GENE FROM EQUINE HERPES VIRUS-1 ENCODING GLYCOPROTEIN gp14

Construction and evaluation of additional recombinant vaccinia virus expressing EHV-1 gp14. The EHV-1 gp14 containing constructs (Example 2) were modified in three ways: (a) varying the length of the EHV-1 gp14 leader sequence; (b) removing excess EHV-1 DNA 3' from the gene; and (c) inserting the modified versions of the EHV-1 gp14 gene into a vaccinia virus vP293 host range selection system (69) for evaluation.

The EHV-1 gp14 gene product contains an unusually long leader sequence. A long hydrophobic sequence extending from amino acids 58 through 99 is proposed to be the signal sequence. This region is preceded by a long hydrophilic sequence. A similar long leader sequence has also been noted for two other gB homologs, pseudorabies virus gll (62) and bovine herpesvirus 1 gl (63).

Modification of the 5' end of EHV-1 gp14. To study the effect of the length of the leader sequence of EHV-1 gp14 on processing, presentation and immunological efficacy of the gp14 product expressed in recombinant vaccinia virus, plasmids containing the EHV-1 gp14 gene with three different lengths of leader sequence were constructed by modifying the previous EHV-1 gp14 containing constructs in the following ways.

Referring now to FIG. 10, plasmid pVM2LH6g14

(Example 2) contains the entire EHV-1 gp14 coding sequence under the control of the H6 promoter inserted into the

Copenhagen vaccinia M2L deletion locus. In pVM2LH6g14, amino acid number 2 of the EHV-1 gp14 gene is present as His rather than the native Ser. To change amino acid 2 to Ser, pVM2LH6g14 was cut with Nsil (recognition sequence ATGCAT) at codons 1 - 2 (Met/His). Mutagenesis was performed (19) using synthetic oligonucleotide MPSYN240 (5' ATCCGTTAAGTTTGTATCGTAATGTCCTCTGGTTGCCGTTCTGTC 3'). The resulting plasmid, pMP14M, contains the entire EHV-1 gp14 gene with the native codon (Ser) at position 2.

Plasmid pVM2LH6g14-1 (Example 2) is identical to pVM2LH6g14 except for a truncation of the leader sequence and introduction of four codons derived from synthetic Nsil linkers. In pVM2LH6g14-1, the sequence of the 5' truncated end of the EHV-1 gp14 gene is ATG/CAT/GCA/TGC/ATT/GCT. . . encoding Met/His/Ala/Cys/Ile/Ala. . .where GCT (Ala) is codon 35 of EHV-1 gp14. pVM2LH6g14-1 was modified by mutagenesis (19) in two ways. To produce a version of the gp14 gene truncated to approximately the same degree as pVM2LH6g14-1 but more closely approximating the native gp14 sequence, pVM2LH6g14-1 was cut with Nsil at codons 1 - 2. Mutagenesis was performed using synthetic oligonucleotide MPSYN241

(5' ATCCGTTAAGTTTGTATCGTAATGAGTGTCCCAGCAGCTGGCTCCTGGATC 3'). In the resulting plasmid, pMP14M-34, the EHV-1 gp14 coding sequence begins with ATG/AGT/GTC/CCA. . .Met/Ser/Val/Pro. . .where CCA (Pro) is amino acid 36 of EHV-1 gp14. The EHV-1 gp14 gene contains an Nael site (GCCGGC) at codons 61 - 63 (Lys/Pro/Ala). To produce a more severely truncated version of the EHV-1 gp14 gene, pVM2LH6g14-1 was linearized with Nael, followed by digestion with Nsil and isolation of vector fragment from an agarose gel. Mutagenesis was performed using synthetic oligonucleotide MPSYN243

(5' ATCCGTTAAGTTTGTATCGTAATGGCATCATCGAGGGTGGGCACAATAGTT 3'). In the resulting plasmid, pMP14M-63, the EHV-1 gp14 coding sequence begins with ATG/GCA. . .Met/Ala. . .where GCA (Ala) is amino acid 63 of the native EHV-1 gp14.

Removal of extraneous EHV-1 DNA. In all EHV-1 gp14 containing plasmids discussed above, the EHV-gp14 coding sequences are followed by approximately 1200 bp of EHV-1 DNA. The termination codon (TAA) for the gp14 gene occurs within a Dral site (TTTAAA) . To remove excess EHV-1 DNA, pMP14M-63 was subjected to partial Dral digestion followed by isolation of linear DNA from an agarose gel, and digestion with PstI which cuts at the junction of EHV-1 DNA and the downstream vaccinia flanking arm. A 6.5 Kb Dral/Pstl DNA band was isolated from an agarose gel.

Synthetic oligonucleotides MPSYN247

(5' AAATTTTTGTTAACTCGAGCTGCA 3') and MPSYN248

(5' GCTCGAGTTAACAAAAATTT 3') were annealed and ligated with the 6.5 Kb fragment. In the resulting plasmid, pMP14M-63P, the EHV-1 gp14 coding sequences are followed immediately by a sequence specifying termination of early vaccinia

transcription (45) followed by a polylinker region

(containing Hpal, Xhol, PstI restriction sites) and the left vaccinia flanking arm derived from Hindlll M.

Insertion of the H6 promoter/EHV-1 gp41 gene into a pHES/vP293 selection system. In all EHV-1 gp14 containing plasmids discussed above, the EHV-1 gp14 gene is under the control of the vaccinia H6 promoter inserted into the M2L deletion locus of Copenhagen strain vaccinia virus. Since the M2L insertion locus is located within a larger region of the genome that can be deleted (69), the relocation of the H6 promoter/EHV-1 gp14 expression cassette to a potentially more stable insertion site was investigated. As a

preliminary step, EHV-1 gp14 gene constructs containing different lengths of the leader sequence were moved to the WR pHES/vP293-based host range selection system (69) to allow rapid generation of vaccinia recombinants for

comparative evaluation.

Plasmid pHES-4 contains the vaccinia H6 promoter, followed by a polylinker region and the KIL human host range gene (70), all inserted between WR vaccinia arms flanking a 21.7 Kb deletion (69). pHES-4 contains two Nrul sites, one within the H6 promoter and one within flanking vaccinia sequences. pHES-4 was linearized by partial digestion with Nrul and the band containing full length linear DNA was isolated from an agarose gel. This linear DNA was cut at the Xhol site in the polylinker region. pMP14M-63P contains two Nrul sites, one within the H6 promoter and the other within EHV-1 gp14 coding sequences, 0.2 Kb from the 3' end of the gene. pMP14M-63P was linearized with Nrul, followed by digestion with Xhol. A 2.8 Kb Nrul (partial)/Xhol fragment was isolated from an agarose gel. This fragment contains part of the H6 promoter, followed by the form of the modified EHV-1 gp14 gene containing the shortest version of the leader sequence. The 2.8 Kb H6 promoter/EHV-1 gp14- containing fragment derived from pMP14-63P was ligated with the Nrul(partial)/Xhol vector fragment derived from pHES-4. The resulting plasmid, pHES-MP63, contains the H6

promoter/EHV-1 gp14 gene cassette with no extraneous EHV-1 DNA. To transfer the H6 promoter/EHV-1 gp14 5' ends

containing full length or moderately truncated leader sequences, plasmids pMP14M and pMP14M-34 were cut with Nrul and the 2.8 Kb and 2.7 Kb bands, respectively, isolated from agarose gels. pHES-MP63 was subjected to partial Nrul digestion and a 7.2 Kb fragment isolated from an agarose gel. The 7.2 Kb vector fragment corresponds to pHES-MP63 from which the 2.6 Kb Nrul fragment containing the H6 promoter/EHV-1 gp14 5' end has been removed. The 7.2 Kb

Nrul (partial) vector fragment derived from pHES-MP63 was ligated with the 2.8 Kb Nrul fragment from pMP14M,

generating pHES-MPl. The 7.2 Kb Nrul (partial) vector fragment derived from pHES-MP63 was also ligated with the 2.7 Kb Nrul fragment from pMP14M-34, generating pHES-MP34. The cloning steps leading to the generation of plasmids PHES-MP63, pHES-MP1 and pHES-MP34 are presented

schematically in FIG. 10.

Plasmids pHES-MP1, pHES-MP34 and pHES-MP63 were used as donor plasmids for recombination with vP293 (69), generating recombinant vaccinia viruses vP753, vP765 and vP721, respectively. Recombinant progeny were selected on human MRC-5 cells.

Evaluation of vP293-based vaccinia virus recombinants expressing the EHV-1 gp14 gene. To determine whether the three forms of the EHV-1 gp14 gene product expressed in recombinant vaccinia virus vP753, vP765 and vP721 were present on the surface of infected cells, VERO cell monolayers were infected with the three EHV-1 gp14- containing recombinant vaccinia viruses. Infected cell monolayers were analyzed for surface immunofluorescence using the EHV-1 gp14-specific monoclonal antibody 3F6.

Surface immunofluorescence was positive for cells infected with all three vaccinia viral recombinants, vP753, vP765 and vP721. This indicates that proper trafficking of the EHV-1 gp14 gene product in vaccinia infected cells is not affected by varying the length of the leader sequence.

To compare the EHV-1 gp14 gene products expressed by the three EHV-1 gp14-containing vaccinia virus

recombinants, MRC-5 cells were infected by vP753, vP765 and vP721 and proteins were metabolically labeled with ³⁵S- methionine. Immunoprecipitations were performed with the radiolabeled cell lysates using EHV-1 gp14-specific

monoclonal antibody 3F6.

Immunoprecipitated proteins from cells infected with vP753, vP765 and vP721 are indistinguishable from each other, and are equivalent to the proteins immunoprecipitated from vP613, the EHV-1 gp14-containing vaccinia recombinant produced from plasmid pVM2LH6g14-1. These results indicate that the variations in length of the EHV-1 gp14 leader sequence tested in these recombinants neither enhance nor interfere with proper processing of the gene product.

To evaluate the protective efficacy of recombinant vaccinia virus expressing the different forms of EHV-1 gp14, hamsters were inoculated with varying doses of vP753, vP765 and vP721 and challenged with EHV-1 hamster adapted Kentucky strain. All three EHV-1 gp14-containing vaccinia

recombinants are protective, with a log₁₀ PD₅₀ of 6.2 or better. Differences in protection among the three vaccinia virus recombinants are not statistically significant.

In contrast with vP577, a subsequent vaccinia virus recombinant which was also generated by recombination between pVM2LH6g14 and vP458 shows an identical EHV-1 gp14 immunoprecipitation pattern to the one seen with vP613, vP753, vP765 and vP721 and, like these EHV-1 gp14 expressing recombinant vaccinia virus, expressed the EHV-1 gp14 protein on the surface of infected cells.

The above data suggest that the EHV-1 gp14

expressed in vaccinia virus recombinant vP577 is defective and the defect probably arose during recombination between the donor plasmid pVM2LH6g14 and vaccinia virus vP458. Example 9 - NUCLEOTIDE SEQUENCE OF THREE NOVEL GENES FROM EQUINE HERPESVIRUS TYPE 1 AND EXPRESSION IN VACCINIA VIRUS RECOMBINANTS

To identify and isolate the EHV-1 gene encoding gp17/18 prior to expressing it in a vaccinia recombinant virus, most of the U_s region of the EHV-1 genome was

sequenced and the different open reading frames found on this DNA fragment were expressed. Three new EHV-1 genes encoded by the S component were identified and analyzed:

EHV-1 gD which on sequencing showed homology with the products of the HSV gD and PRV gp50 genes, EHV-1 gp63 which showed homology with the products of the HSV US7 and PRV gp63 genes, and EHV-1 gE which showed homology with the products of the HSV gE and PRV gl genes. All three genes, either individually or in association, were cloned in a host range selection system of the Copenhagen vaccinia strain for rapid expression studies. Immunofluorescence obtained with an anti-EHV-1 rabbit serum revealed the expression of EHV-1 specific products.

Cloning of the EHV-l BamHI D fragment. As the

EHV-1 gp17/18 gene was located on the S component of the EHV-1 genome (3), the BamHI D fragment which represents most of the U_s region (59) was isolated and cloned. EHV-1 genomic DNA of Kentucky D strain was digested with BamHI. The 11.0 Kb BamHI D fragment was isolated from agarose gel (Geneclean, Bio101, Inc., La Jolla, CA) and cloned in plasmid pIBI24 as plasmid pEHVBamHID. A restriction map of this fragment was derived (FIG.11).

Identification of DNA sequences encoding EHV-1 gD, gp63 and gE. Nucleotide sequence data for both strands were obtained from several subclones of the BamHI D fragment subcloned in pIBI24, as described in Example 1. Sequences of the junctions between consecutive fragments were checked on the initial clone pEHVBamHID. The PC/GENE software package (Intelligenetics Inc., Mountain View, CA) was used in all sequence data analyses.

DNA sequence analysis of the EHV-1 gD, gp63 and gE genes. The DNA sequence analysis of the 6402 bp region sequenced from the BamHI D fragment (representing most of the unique short region) revealed the existence of at least three complete open reading frames reading all from the same strand. This sequence is presented in FIG. 12 as the rightward 5' to 3' strand. The base composition is 50.44% G + C.

The first open reading frame (ORF1) extended from nucleotide positions 971 to 2176. Putative transcriptional regulatory signals were found in the region 5' to the most probable ATG initiation codon at position 971. A TATA box having the sequence TATATTAA (nucleotides 871 to 878) was located 60 nucleotides downstream from a putative CAT box at positions 811 to 817 having the sequence TGACAAT. No polyadenylation signal (AATAAA) was found downstream of the TAA termination codon (nucleotides 2177 to 2179). Seven out of ten nucleotides in the sequence 5' TCCCTTCGCC 3'

(nucleotides 890 to 899) are complementary to the 18S ribosomal RNA sequence 3' AGGAAGGCGT 5' (61) and may serve as the ribosome binding site. A scanning model has been proposed by which eukaryotic mRNAs initiate translation (151). The cardinal rule of this model is that ribosomes bind to the 5' end of the mRNA and linearly scan the mRNA molecule. Commitment to the translation initiation is usually at the first 5' proximal ATG codon although

exceptions have been noted (152). A purine in position -3 is essential for translation initiation and translation is stimulated by C in positions -1 and -2 when the rest of the sequence is suboptimal (155). The sequence context around the proposed initiation codon AGCATGT (nucleotides 968 to 974) qualifies as a functional sequence context for

translation initiation of eukaryotic mRNA. There are two other possible ATG initiation codons located respectively at positions 989 to 991 and 992 to 994. The context of these two codons CTTATGATGG does not qualify as functional for translation initiation. The EHV-1 ORF1 encodes 402 amino acids with a calculated molecular mass of 45239 daltons.

Analysis of the EHV-1 ORF1 protein structure.

Analysis of the amino acid sequence revealed a number of features common to membrane-associated glycoproteins. A region extending from amino acids 1 to 26 had a characteristic hydrophobicity profile and is proposed to be the signal sequence. A hydrophobic region consisting of 24 amino acids (amino acids 351 to 374) is predicted to

function as a transmembrane anchor domain. There are four Asn-X-Thr/Ser (where X can be any amino acid except proline) sites for potential N-linked glycosylation (157). The hydrophobicity profile of the EHV-1 ORF1 amino acid sequence is shown in FIG. 13. The characteristics of a membrane spanning glycoprotein including signal and anchor elements are clearly defined. The two most hydrophobic regions at the N- and near the C-termini are predicted to represent the signal sequence and transmembrane spanning region,

respectively, of the glycoprotein molecule.

Comparison of the EHV-1 ORF1 amino acid sequence to other herpesvirus glycoproteins. Comparison of the amino acid composition of the putative EHV-1 ORF1 protein revealed significant homology with glycoproteins of other

herpesviruses. Thus, the EHV-1 ORF1 protein is similar to PRV gp50 (95) and HSV-1 gD (79,160).

The second open reading frame (ORF2) extended from nucleotide positions 2287 to 3525. No putative

transcriptional regulatory signals were found in the region 5' to the ATG initiation codon at position 2287. No AATAAA polyadenylation signal was found downstream of the TGA termination codon (nucleotides 3526 to 3528) but two

potential YGTGTTYY polyadenylation signals (180) are located downstream of this termination codon at approximately 40 and 70 bp. The sequence context around the proposed initiation codon GCTATGG is consistent with Kozak's rules (151,155). There are at least two other possible ATG initiation codons at positions 2305 to 2307 and 2332 to 2334 but the sequence context of these two codons (GGGATGT and TCTATGG) does not qualify as functional for translation initiation. The EHV-1 ORF2 encodes a 413 amino acid polypeptide with a calculated molecular mass of 45431 daltons.

Analysis of the EHV-1 ORF2 protein structure.

Analysis of the amino acid sequence revealed a number of features common to membrane-associated glycoproteins. A region extending from amino acids 1 to 22 had a characteristic hydrophobicity profile and is proposed to be the signal sequence (although the computer score for the putative cleavage site was low). A hydrophobic region consisting of 32 amino acids (positions 315 to 346) is predicted to function as a transmembrane anchor domain.

There are seven Asn-X-Thr/Ser sites for potential N-linked glycosylation. A hydrophobicity plot of the EHV-1 ORF2 amino acid sequence is shown in FIG. 14. The

characteristics of a membrane spanning glycoprotein

including signal and anchor elements are clearly defined. The two most hydrophobic regions at the N- and near the C- termini are predicted to represent the signal sequence and transmembrane spanning region, respectively, of the

glycoprotein molecule.

Comparison of the EHV-1 ORF2 amino acid sequence to other herpesvirus glycoproteins. Comparison of the amino acid composition of the EHV-1 ORF2 revealed significant homology with glycoproteins of other herpesviruses. Thus, the EHV-1 ORF2 protein is homologous to PRV gp63 (80), VZV gpIV (181) and HSV-1 US7 (79).

The third open reading frame (ORF3) extended from nucleotide positions 3796 to 5451. Putative transcriptional regulatory signals were found in the region 5' to the ATG initiation codon at position 3796. A TATA box having the sequence GTTTAAA (nucleotides 3705 to 3711) was located 50 nucleotides downstream of a putative CAT box at positions 3649 to 3654 having the sequence GCAATG. No evident

polyadenylation signal was found downstream of the TGA termination codon (nucleotides 5452 to 5454). The sequence context around the proposed initiation codon ACAATGG is consistent with Kozak's rules (151,155). The EHV-1 ORF3 encodes a 552 amino acid polypeptide with a calculated molecular mass of 61493 daltons.

Analysis of the EHV-1 ORF3 protein structure.

Analysis of the amino acid sequence revealed a number of features common to membrane-associated glycoproteins. A region extending from amino acids 1 to 23 had a

characteristic hydrophobicity profile and is proposed to be the signal sequence. A hydrophobic region consisting of 38 amino acids (positions 404 to 437) is predicted to function as a transmembrane anchor domain. There are five Asn-X- Thr/Ser sites for potential N-linked glycosylation. A hydrophobicity plot of the EHV-1 ORF3 amino acid sequence is shown in FIG. 15. The characteristics of a membrane

spanning glycoprotein including signal and anchor elements are clearly defined. The two most hydrophobic regions at the N- and near the C-termini are predicted to represent the signal sequence and transmembrane spanning region,

respectively, of the glycoprotein molecule.

Comparison of the EHV-1 ORF3 amino acid sequence to other herpesvirus glycoproteins. Comparison of the amino acid composition of the EHV-1 ORF3 protein revealed

significant homology with glycoproteins of other

herpesviruses. Thus, the EHV-1 ORF3 protein is homologous to PRV gl (80), VZV gE (181) and HSV-1 gE (79).

Construction of a Copenhagen vaccinia virus based host range selection system. A Copenhagen vaccinia virus based host range selection system similar to the WR

pHES/vP293 host range selection system (69) was constructed.

Copenhagen vaccinia virus deletion mutant vP668 is deleted for 12 genes from the Hindlll C through Hindlll K region, including both human host range genes KIL (70) and C7L, a gene which maps to Hindlll C. vP668 is unable to grow on human MRC-5 cells. Members of the COPCS plasmid series contain the C7L gene within flanking vaccinia arms, allowing recombination with vP668 and restoration of the ability of the virus to grow on MRC-5 cells. The ability of recombinant vaccinia progeny generated by recombination using the vP668/COPCS host range selection system to plaque on human MRC-5 cells provides a means of rapid

identification of these recombinants. Plasmid pCOPCS657 contains the synthetic H6 vaccinia promoter followed by a polylinker cloning region for the insertion of foreign genes. The polylinker region is followed by stop codons and a vaccinia transcriptional termination signal (45).

Cloning of the EHV-1 gD gene into pCOPCS657.

Referring now to FIG. 16, plasmid pEHVBamHID was digested with Hindlll and a 1240 bp Hindlll DNA fragment containing EHV-1 gD was isolated from an agarose gel (Geneclean, Bio10, Inc., La Jolla, CA) and repaired using the Klenow fragment of DNA polymerase. The repaired fragment was then ligated into plasmid pCOPCS657 digested with Smal. The resulting plasmid, pJCA006, has the ATG initiation codon approximately 10 bp from the H6 promoter (FIG. 16).

Cloning of the EHV-1 gp63 gene into PCOPCS657.

Plasmid pEHVBamHID was digested with Hindlll. EcoRI and

PvuII and the 1300 bp Hindlll-PvuII DNA fragment containing EHV-1 gp63 was isolated from an agarose gel and repaired with Klenow. The repaired fragment was then ligated into plasmid pC0PCS657 digested with Smal. The resulting plasmid with EHV-1 gp63 in the proper orientation relative to the H6 promoter was designated pJCA008 (FIG. 16).

Cloning of the EHV-1 gE gene into pCOPCS657.

Plasmid pEHVBamHID was digested with Aatll and Apal and a 2630 bp Aatll-Apal DNA fragment containing EHV-1 gE was isolated from an agarose gel and repaired with Klenow. The repaired fragment was then inserted into plasmid pC0PCS657 digested with Smal . The resulting plasmid with the EHV-1 gE gene in the right orientation relative to the H6 promoter was designated pJCA007 (FIG. 16).

Cloning of the EHV-1 gD-gp63 fragment into

pCOPCS657. Referring now to FIG. 17, plasmid pEHVBamHID was digested with EcoRI and PvuII and the 1832 bp EcoRI-PvuII DNA fragment (A) was isolated from an agarose gel. Plasmid PJCA006 was digested with Clal and EcoRI and the 1450 bp

Clal-EcoRI DNA fragment (B) was isolated from an agarose gel. Plasmid pCOPCS657 was digested with Clal and Smal and the 3700 bp Clal-Smal DNA fragment (C) was isolated from an agarose gel. Fragments A, B and C were then ligated

together and the resulting plasmid was designated pJCA009 (FIG. 17).

Cloning of the EHV-1 gD-gp63-gE fragment into PCOPCS657. Plasmid pEHVBamHID was digested with EcoRI and SacII and the 4240 bp EcoRI-SacII DNA fragment (D) was isolated from an agarose gel. Fragment D was then ligated with fragments B and C (see above) with addition of dNTPs to ensure the repair of the junction SacII-Smal. The resulting plasmid was designated pJCA010 (FIG. 17).

Construction of recombinant vaccinia viruses vP773, vP803, vP809, vP810 and vP822 expressing the EHV-1 U_s open reading frames. In order to check quickly the

expression of the EHV-1 open reading frames described above, a number of vaccinia recombinant viruses were constructed using the COPCS host range selection system. The three open reading frames identified from the sequence analysis were cloned either individually or in association ("double" and "triple") in plasmid pCOPCS657 (FIGS. 16, 17). The resulting plasmids were then used for recombination with vaccinia recombinant vP668 as rescuing virus. The different

recombinant vaccinia viruses issued from these

recombinations are presented in Table 5.

Vaccinia recombinant vP773 was obtained from recombination performed with donor plasmid pJCA006

containing the EHV-1 gD gene. Vaccinia recombinant vP822 was obtained from recombination performed with donor plasmid pJCA008 containing the EHV-1 gp63 gene. Vaccinia

recombinant vP803 was obtained from recombination performed with donor plasmid pJCA007 containing the EHV-1 gE gene. Vaccinia recombinant vP809 was obtained from recombination performed with donor plasmid pJCA009 containing the EHV-1 gD-gp63 fragment and vaccinia recombinant vP810 was obtained from recombination performed with donor plasmid pJCA010 containing the EHV-1 gD-gp63-gE fragment (Table 5).

Immunofluorescence analysis of EHV-1 ORF1 (gD). ORF2 (qp63) and ORF3 (gE) products synthesized by single or multiple recombinant vaccinia viruses. Immunofluorescence of recombinant vaccinia virus infected VERO and MRC-5 cells was performed as described in Example 1 using anti-EHV-1 specific polyclonal rabbit serum R5935 (1:200) (Table 6). Table 5. Designation of vaccinia virus recombinants expressing EHV-1 gD, gE and gp63 genes.

Table 6. Immunofluorescence of recombinant vaccinia virus infected cells performed using anti-EHV-1 rabbit serum R5935.

Example 10 - IMMUNOLOGICAL EVALUATION IN MICE AND SWINE OF FBEUDORABIEB VIRUS GLYCOPROTEINS gpll, gplII AND gp50 EXPRESSED INDIVIDUALLY OR IN

COMBINATION BY VACCINIA VIRUS RECOMBINANTS

The Copenhagen strain of vaccinia virus and its derivatives vP410, vP425 and vP458 (184) were utilized in this example.

Cloning of the PRV genes encoding gpll. gpIII and gp50. PRV NIA₃ virus (182) was propagated on NIL₂ cell culture (183). Cellular debris was removed from the

supernatant by centrifugation at 3,000 xg for 30 minutes. The virions were purified by centrifugation through a 40% (wt/vol) sucrose cushion at 40,000 rpm for 60 minutes in a 45 Ti Beckman rotor followed by a discontinuous 30-50%

(wt/vol) sucrose gradient (SW25 Beckman rotor at 23,000 rpm for 5 hours). Banded virions were collected, diluted with TNE buffer (50 mM Tris-HCl, pH7.8, 150 mM NaCl and 10 mM EDTA) and pelleted at 30,000 rpm for 1 hour in an SW40

Beckman rotor. The viral pellet was resuspended in TE buffer (50 mM Tris-HCl pH7.8, 10 mM EDTA) and lysed by addition of sodium dodecyl sulfate to a final concentration of 0.5% (wt/vol) and proteinase K to 100 mg/ml. After incubation at 37°C for 2 hours the lysate was extracted once with phenol:chloroform (1:1) and once with

chloroform: isoamylalcohol (24:1). The DNA was precipitated with ethanol and redissolved in H₂O. After complete

digestion with BamHI the fragments were cloned into the

BamHI site of pBR322 previously treated with calf intestine alkaline phosphatase (CIAP). The ligation mixture was used to transform competent E. coli strain NM522 (20).

Referring now to FIGS. 18 and 19, the DNA sequence encoding the gpll gene resides in the BamHI fragment 1 and Sall subfragments 1A and 1B of the PRV genome (62, 94). The plasmid designated pPR9.25 containing the PRV BamHI fragment 1 inserted into the BamHI site of pBR322 was digested with Ncol. The resulting DNA digest was fractionated on a 0.8% agarose gel and a 6.2 Kb Ncol DNA fragment was purified using Gene Clean™ procedure (Bio101, Inc. La Jolla, CA) and subsequently inserted into the Ncol site of pBR328 (Boehringer Mannheim Biochemicals, Indianapolis, IN) treated with CIAP. The resulting plasmid pPR2.15 was digested with SphI and fractionated on an agarose gel. The 2.7 and 1.8 Kb fragments were purified and inserted into the SphI site of phosphatased pUC18 to create plasmids pPRl and pPR2 (FIG. 18) and into M13 phage. Nucleotide sequence was determined as described above. The DNA sequence analysis revealed an open reading frame of 2742 bp encoding 913 amino acids.

Significant amino acid homology to the HSV-1 gB was observed as expected (62). To facilitate the description of the cloning manipulations for expression of PRV gpll in vaccinia virus vectors, the DNA sequence of the PRV gpll open reading frame plus additional 5' and 3' non-coding sequences is shown in FIG. 19.

Referring now to FIGS. 20 and 21, the DNA sequence encoding the PRV glycoprotein gpIII resides in the BamHI fragments 2 and 9 of the PRV genome (96). The plasmid pPR9.9 containing the BamHI fragment 2 inserted into the

BamHI site of pBR322 (FIG. 20) was digested with BamHI and SphI. The plasmid pPR7.5 containing the BamHI fragment 9 inserted into the BamHI site of pBR322 was digested with

Ncol and BamHI. The DNA resulting from both digestions was fractionated on an agarose gel. The 2.35 Kb SphI-BamHI fragment and the 1.1 Kb Ncol-BamHI fragment were purified and ligated into the EcoRI-SphI sites of phosphatased IBI25 (FIG. 20) using an Ncol-EcoRI phosphorylated linker

MRSYN21/MRSYN22

Ncol ECORI

MRSYN21 5' CATGGGTCTGCAGTCG 3'

MRSYN22 3' CCAGACGTCAGCTTAA 5'

A plasmid designated pPR17 was isolated which contained a 3450 bp SphI-Ncol fragment including the complete PRV gpIII gene (FIG. 20). The nucleotide sequence was obtained from double stranded plasmid templates denatured with alkali and from single stranded templates after cloning into M13 phage. The DNA sequence analysis revealed an open reading frame of 1440 bp encoding 479 amino acids (FIG. 21). Significant homology to HSV gC was observed as previously reported (96). Referring now to FIGS. 22 and 23, the DNA sequence encoding the PRV glycoprotein gp50 resides in the BamHI

fragment 7 of the PRV genome (95). Plasmid pPR7.1 (FIG. 22) containing the PRV BamHI fragment 7 inserted into the BamHI site of pBR322 was digested with StuI and Ndel and treated with Mung bean nuclease. The 1.7 Kb fragment was purified from an agarose gel, inserted into the HincII site of

phosphatased IBI25. This plasmid, pPR22, (FIG. 22) contains the entire PRV gp50 gene. Determination of the nucleotide sequence revealed a 1215 bp open reading frame encoding 404 amino acids (FIG. 23). Significant homology to the HSV-1 gD was observed as previously reported (95).

Cloning of the PRV genes encoding gpll, gpIII and gp50 into vaccinia virus insertion donor plasmids. The 1060 bp PRV Sphl-Nhel fragment from pPRl (FIG. 18A) was isolated from an agarose gel and inserted into the BamHI-SphI sites of pIBI25 after treatment with CIAP using a BamHI-Nhel

phosphorylated linker MRSYN1/MRSYN2

BamHI Nhel

MRSYN1 5' GATCCATTCCATGGTTG 3'

MRSYN2 3' GTAAGGTACCAACGATC 5' to generate plasmid pPR6 (FIG. 18A).

pPR6 was digested with Hindlll and Apal and treated with CIAP. The Apal site is located 32 bp

downstream from the ATG initiation codon of PRV gpll (FIG.

19). A double stranded DNA fragment was obtained by

annealing the pair of synthetic phosphorylated

oligonucleotides MRSYN3/MRSYN4. This fragment contains DNA specifying the vaccinia H6 promoter from the EcoRV site

through the ATG (underlined), followed immediately by PRV gpll coding sequences.

HindllIEcoRV Apal

MRSYN3 5' AGCTTGATATCCGTTAAGTTTGTATCGTAATGCCCGCTGGTGGCGGTCTTTGGCGCGGGCC 3' MYSYN4 3' ACTATAGGCAATTCAAACΑTAGCATTACGGGCGACCACCGCCAGAAACCGCGC 5'

The synthetic DNA was ligated to the 3920 bp Hindlll-Apal fragment derived from pPR6 to generate plasmid pPR9 (FIG.

18A). Plasmid pPR9 was digested with BamHI and Nhel,

treated with CIAP and ligated using a phosphorylated BamHI- Sphl linker

SphI BamHI

MRSYN7 5' CCCAGATCTCCTTG 3'

MRSYN83' GTACGGGTCTAGAGGAACCTAG 5"

to a 1640 bp Sphl-Nhel fragment obtained from pPRl

generating plasmid pPR12 (FIGS. 18A,18B).

The 1030 bp HincII-SphI fragment from pPR2 (FIG.

18A) was isolated from an agarose gel and inserted into the

HincII-SphI sites of phosphatased pUC10. The resulting

plasmid pPR10 was digested with Hindlll and Nael and treated with CIAP. The Nael site is located 44 bp upstream of the

TAG termination codon (FIG. 19). A double stranded DNA

fragment obtained by annealing the pair of phosphorylated

synthetic oligonucleotides MRSYN9/MRSYN10

Nael Xmalll Hindlll

MRSYN9 5' GGCACTACCAGCGCCTCGAGAGCGAGGACCCCGACGCCCTGTAGAATTTTTATCGGCCGA 3' MRSYN103' CCGTGATGGTCGCGGAGCTCTCGCTCCTGGGGCTGCGGGACATCTTAAAAATAGCCGGCTTCGA 5' was ligated to the 3720 bp Nael-Hindlll fragment derived

from pPR10 to generate the plasmid pPR11.

The underlined sequences correspond to the PRV gpll termination codon and to a vaccinia early transcription termination signal (45). The 770 bp Sphl-HincII fragment

from pPR2 was purified from an agarose gel and inserted

using a BamHI-SphI phosphorylated linker (MRSYN7/MRSYN8)

into the BamHI-HincII sites of CIAP-treated pPR11 to

generate pPR13 (FIGS. 18A,18B). Plasmid pPR12 digested with

EcoRI and SphI and treated with CIAP was ligated using a

phosphorylated Hindlll-EcoRI linker (MRSYN19/MRSYN20)

Hindlll EcoRI

MRSYN19 5' AGCTTCTGCAGCCATGGCGATCGG 3'

MRSYN20 3' AGACGTCGGTACCGCTAGCCTTAA 5'

to a 990 bp Hindlll-SphI isolated fragment derived from

pPR13 to generate plasmid pPR15 (FIG. 18B).

The Hindlll-EcoRV digested 2780 bp fragment from pPR15 was treated with Mung bean nuclease, purified from an agarose gel and inserted into plasmid pTP15 (184) (FIG.3)

which had been digested with Xmalll-EcoRV, Mung bean

nuclease and CIAP to generate plasmid pPR18 (FIG. 18B). In pPR18, PRV gpll is linked with the synthetic vaccinia H6 promoter in the vaccinia hemagglutinin deletion locus. This plasmid was transfected into vaccinia virus infected cells to generate vaccinia recombinants vP534, vP644, v621 and vP692 containing the PRV gpll gene (see below).

The PRV gpIII gene was manipulated to be expressed under the control of the early vaccinia virus promoter, μ , (see below) located in the vaccinia Hindlll B fragment.

Using site-specific mutagenesis, an Nsil site was introduced by changing the sequence CGC (bases 192-194) (FIG. 21) in

PRV gpIII to ATG and an Xbal site was introduced by changing the sequence GTGACGT to TTCTAGA (bases 1632-1638) (FIG. 21). To do this single stranded DNA was generated from plasmid pPR17 using a helper phage R408 (Stratagene, La Jolla, CA) (185). The site directed mutagenesis was performed using two purified phosphorylated synthetic oligonucleotides

MRSYN5 and MRSYN6.

Nsil

MRSYN5 5'GCGAGCGAGGCCATGCATCGTGCGAATGGCCCC 3'

Xbal

MRSYN6 5' GGGGGGACGCGCGGGTCTAGAAGGCCCCGCCTGGCGG 3" and selection on E. coli dut- ung- strain CJ236 (IBI, New Haven, CT) (17,166).

These mutations generated plasmid pPR28. Plasmid pPR28 was digested with Nsil and Xbal and treated with Mung bean nuclease. A 1440 bp fragment was purified from an agarose gel and inserted into the Bglll-Hpal sites of pSD478VC (FIGS. 20,24) after treatment with Mung bean nuclease and CIAP. Plasmid pPR24 was transfected into vaccinia virus infected cells to generate vaccinia virus recombinants vP604, vP644, vP691 and vP692 containing the PRV gpIII gene (see below).

PRV gp50 was manipulated to be expressed under the control of an early/intermediate vaccinia virus promoter, I3L (167). Using site-specific mutagenesis, an Nsil site was introduced by changing the sequence, CCTGCCAGCGC (bases 177-167) (FIG. 23) in gp50 to ATGCATTTAAT and a Bglll site was introduced by changing the sequence CCTCCGCAGTACCGG at bases 1404-1418 (FIG. 23) to AATTTTTATAGATCT. Previously described procedures (17,185,186) of mutagenesis were employed to generate plasmid pPR29 from pPR22 using

purified, phosphorylated synthetic oligonucleotides MRSYN12 and MRSYN13 (FIG. 22).

Nsil

MRSYN12 5'GGTTCCCATACACTCAATGCATTTAATCATGCTGCTCGCAGCGC 3'

BgIII

MRSYN13 5'GCAGCCCGGTCCGTAGAATTTTTATAGATCTCGTCGATGATGATGGT 3' pPR29 was digested with Nsil, treated with Mung bean nuclease and partially digested with Bglll to generate a 1290 bp fragment. Plasmid pMP13PP (FIGS. 22,25) was digested with EcoRI, treated with Mung bean nuclease and then with BamHI to generate a 140 bp fragment containing the vaccinia I3L promoter. The 1290 and 140 bp fragments were purified from agarose gels and ligated into the phosphatased Bglll site of pMP409DVC (FIGS.4,22). The resulting plasmid, pPR26, was used in recombination to produce vaccinia virus recombinants vP591, vP621, vP691 and vP692 containing the gp50 gene (see below).

Construction of vaccinia recombinants expressing PRV glycoproteins gpll. gpIII and gp50 individually or in combinations. In order to assess the immunogenicity and relative contribution of the three PRV glycoproteins (gpll, gpIII and gp50) to protection of immunized animals against virulent PRV challenge, a series of vaccinia recombinants were constructed expressing the three PRV glycoproteins alone or in combination.

Referring now to FIG. 24, recombinant vaccinia virus, vP533, expressing the Beta-galactosidase gene was constructed as follows: A 1 Kb region within vaccinia

Hindlll fragment B spanning the Sall F/I junction of the Copenhagen genome contains DNA homology with the hemorrhagic (μ) gene of cowpox virus (188) as determined by Southern blot analysis (189). The μ gene encodes a polypeptide with similarity to serine protease inhibitors and biologically is responsible for hemorrhagic pock formation by virus on the chorioallantoic membrane. The DNA sequence of the

Copenhagen genome revealed that the μ gene equivalent contained multiple frameshift mutations and was biologically non-functional. Plasmid pSD419VC (184) (FIG. 24) contains the left portion of the μ region. Plasmid pSD422VC, which contains the Copenhagen Sall fragment I cloned into pUC8, contains the remainder of the μ region. To remove unwanted vaccinia sequences to the left, pSD419VC was digested with Ncol and Smal, blunt-ended with the Klenow fragment of E. coli polymerase and religated resulting in plasmid pSD476VC (FIG. 24). Plasmid pSD422VC was digested with Hpal and Nrul and an approximately 0.3 Kb fragment located immediately to the right of the μ region was isolated from an agarose gel. This fragment was ligated into pSD476VC cut with HincII (which recognizes Sall sites) resulting in plasmid pSD477VC. To express Beta-galactosidase under the control of the

Copenhagen vaccinia μ promoter region, synthetic

oligonucleotides 22mer/20mer were prepared. The sequence of 22mer/20mer with restriction sites indicated and ATG

initiation codon underlined is as follows:

Clal Hpal

22mer 5' CGATTACTATGAAGGATCCGTT 3'

20mer 3' TAATGATACTTCCTAGGCAA 5"

The annealed 22mer/20mer mixture was ligated into pSD477VC digested with Clal and HincII resulting in the novel plasmid pSD479VC (FIG. 24). A 3.1 Kb BamHI fragment containing the E. coli Beta-galactosidase coding sequences from pMC1871 (34) devoid of initiation codon and promoter was ligated into pSD479VC cut with BamHI. The resulting plasmid

containing the lacZ gene in the proper orientation under the control of the Copenhagen μ promoter was designated

pSD479VCBG. This insertion donor plasmid was recombined into vaccinia virus vP410 (184). A recombinant vaccinia virus was identified on the basis of blue plaque formation in the presence of the chromogenic substrate, X-gal (9,24), plaque cloned and designated vP533 (FIG. 24).

To construct a vector plasmid for the insertion of foreign genes, synthetic oligonucleotides 42mer/40mer were prepared.

Clal Bglll SacI Smal Xhol BamHI Hpal

42mer 5' CGATTACTAGATCTGAGCTCCCCGGGCTCGAGGGGATCCGTT 3'

40mer 3' TAATGATCTAGACTCGAGGGGCCCGAGCTCCCCTAGGCAA 5' The annealed 42mer/40mer mixture was ligated into pSD477VC cut with Clal and HincII resulting in the novel plasmid pSD478VC (FIG. 24). This plasmid contains approximately 0.3 Kb of vaccinia sequences on each side of the multicloning region which completely replaces the μ coding region of the Copenhagen strain of vaccinia. pSD478VC was used to

generate pPR24 (FIG. 20) containing PRV gpIII coding

sequences and vaccinia recombinants vP604, vP644, vP691 and vP692.

Referring now to FIG. 25, plasmid pMP419 contains an 850 bp BamHI fragment from vaccinia Hindlll fragment I containing the I3L promoter inserted into the BamHI site of pUC8 (FIG. 25). The I3L promoter element corresponds to DNA sequences upstream of the I3L open reading frame in the vaccinia Hindlll fragment I (187) and has been used

previously to express foreign genes in vaccinia virus recombinants (27,190). pMP419 was linearlized at the unique Clal site within I3L coding sequences and subjected to Bal 31 digestion followed by digestion with EcoRI and blunt- ending by treatment with the Klenow fragment of E. coli polymerase. The resulting plasmid, pMP419-5, (FIG. 25) contains the I3L promoter sequences upstream of nucleotide - 8 linked to an EcoRI site. The promoter element was

isolated as anEcoRI-Mspll fragment from pMP419-5 and

inserted into EcoRI-Clal digested pUC13C, a pUC13 derivative containing a Clal linker at the Smal site. The resulting plasmid, pMP13PP, (FIGS. 22,25) contains the I3L promoter sequences from position -126 through position -8 followed by an EcoRI site at position -8.

PRV gp50 driven by the vaccinia I3L promoter was inserted into the M2L deletion plasmid vector pMP409DVC (FIG.4) resulting in pPR26 (FIG. 22). pPR26 was used to generate vaccinia recombinants vP591, vP621 and vP691 and vP692.

Isolation of recombinant vaccinia viruses.

Recombinant vaccinia viruses containing the PRV genes were identified and purified as described above. Recombinant vaccinia viruses expressing the three PRV glycoproteins gpll, gpIII, and gp50 alone or in combination are listed in Table 7.

T

In vitro evaluation of the PRV glycoproteins expressed bv vaccinia virus recombinants. The PRV

glycoproteins gpll, gpIII and gp50 are typical glycoproteins associated with the membranous structure of PRV infected cells and are additionally components of the virus. Anti- gpll, anti-gpIII and anti-gp50 specific monoclonal

antibodies followed by fluorescein conjugated goat anti- mouse IgG gave a strong surface immunofluorescence on cells infected with the recombinant vaccinia viruses but not in wildtype vaccinia virus infected cells.

In vivo evaluation of the immunogenic potential of PRV glycoproteins gpll, gpIII and gp50 expressed bv vaccinia virus recombinants in mice and swine. In order to assess the relative immunogenicity of the three PRV glycoproteins expressed by vaccinia virus recombinants , mice were

inoculated in the footpad with 50 to 100 ul of different doses of the recombinant viruses. Fourteen days after the immunization the mice were challenged with 10 LD₅₀ of the virulent Kojnock strain of PRV by the intraperitoneal route. In preliminary experiments each of the PRV glycoproteins were shown to be efficacious in protecting inoculated mice against a virulent PRV challenge. In a more extended series of experiments utilizing over 500 mice, the efficacy of vaccinia recombinants expressing PRV glycoproteins was assessed. The vaccination dose able to protect 50% of the challenged mice (PD₅₀) was calculated and the results of these studies are shown in Table 8. Recombinant vaccinia virus expressing individually PRV glycoproteins gpll, gp50 and gpIII generate calculated PD₅₀ values of 6.4, 5.4 and 5.8 (log₁₀), respectively. When the glycoproteins are expressed in combination significantly better PD₅₀ values are calculated. The vaccinia recombinant expressing PRV gpll plus gp50 generated a PD₅₀ value of 3.3, whereas the vaccinia recombinant expressing PRV gp50 plus gpIII results in an essentially similar PD₅₀ value (3.6). Apparently more efficacious is the recombinant expressing PRV glycoproteins gpll plus gpIII where a PD₅₀ of 1.5 is obtained.

Coexpression of all three PRV glycoproteins gpll, gpIII and gp50 in a recombinant vaccinia virus does not provide a PD₅₀ value significantly lower than those obtained with the recombinant viruses expressing the three PRV glycoproteins individually. The potentiated efficacy obtained with the vaccinia recombinant expressing gpll and gpIII compared to vaccinia recombinant virus expressing the genes individually is similar to the results reported in Example 6 for the coexpression of equine herpesvirus glycoproteins gp13 and gp14.

0

Although the mouse can provide an interesting model system for evaluation of PRV glycoprotein

immunogenicity, the major target species of a PRV vaccine is swine. Therefore, in order to assess the validity of the recombinant vaccinia virus approach in swine the following experiment was performed. Piglets of approximately 25 kg were inoculated intramuscularly with 2 ml of the vaccinia recombinants expressing combinations of the PRV

glycoproteins gpll, gpIII and gp50. Virus inoculum was diluted in PBS. Thirty five days after this inoculation, the piglets were challenged by an intranasal injection (1 ml into each nostril) of a virulent PRV isolate NIA3

suspension. The effectiveness of vaccination was evaluated by measuring comparative weight gain of vaccinated and control piglets for seven days after challenge. Relative weight gain is calculated as the daily mean percentage weight gain observed in vaccinated pigs minus the daily mean percentage weight gain of unvaccinated control pigs. Normal weight gain of pigs in unperturbed conditions is greater than 1.1 kg. As demonstrated by the data in Table 9, weight evolution during the seven day period after PRV challenge is greatly enhanced in the vaccinated piglets over the wildtype virus inoculated control set. A single inoculation with the vaccinia virus recombinants gives significant protection against weight loss after virulent PRV challenge.

The availability of vaccinia virus recombinants expressing the three dominant PRV glycoproteins individually or in combination offer a number of advantages to the control of PRV infections in the field: (a) one significant advantage is that the recombinant vaccinia viruses as vaccinating agents express only a limited number of PRV genes and, therefore, there is no attendant risk of

reversion of an attenuated PRV vaccine strain to a virulent form and, therefore, there is no continued introduction of PRV virus into the environment; (b) since only a limited number of PRV antigens are expressed by the vaccinia virus recombinant PRV vaccine candidates, this allows the

discrimination of vaccinated versus naturally infected animals since diagnostic reagents consisting of other PRV antigens could be assembled to discriminate between

vaccinated and naturally infected animals; and (c) such recombinant vaccines could be useful in disrupting the natural vertical transmission of PRV from sow to offspring. This could be accomplished by the vaccination of the

pregnant sow by a vaccinia virus recombinant expressing a discrete set of PRV glycoproteins. Maternal immunity should protect the offspring from PRV infection. In turn, the offspring then could be vaccinated with a vaccinia virus recombinant expressing yet a different configuration of PRV antigens distinct from those used to vaccinate the sow.

This is one potential way to break through maternal

immunity. Another approach to address the issue of maternal immunity would be to express the PRV glycoproteins in whatever combination in a completely heterologous vector. This is achieved by the construction of avipox virus

recombinants expressing PRV glycoproteins. The utility of avipox virus recombinants whose natural host range is restricted to avian species, in the vaccination of non-avian species has been demonstrated (41). Thus, two approaches are available for addressing the issue of the barrier provided by maternal immunity: (1) the vectors and (2) the constellation of the antigens expressed by those vectors. Example 11 - AVIPOX VECTORS EXPRESSING THE PSEUDORABIES VIRUS GLYCOPROTEIN gpII

Canarypoxvirus was propagated on primary chick embryo fibroblasts (CEF) derived from 10 to 11 day old embryonated eggs obtained from SPAFAS, Inc. (Norwich, CT) using conditions described previously (41,42). Virus was purified from host cell contaminants by sucrose gradient centrifugation using the method described by Joklik (191). Pig kidney (PK-1) cells were obtained from American Type Culture Collection, Rockville, MD (ATCC #CL101).

Construction of a canarypoxyirus recombinant expressing the pseudorabies virus gpll glycoprotein.

Referring now to FIG. 26, the plasmid pPR15 (FIG.18) was utilized as the source of the PRVgpII gene. To isolate the DNA segment containing the entire PRVgpII gene, pPR15 was digested with EcoRV and Hindlll. A fragment of

approximately 2.8 Kb containing 21 bp of the 3' end of the vaccinia virus (W) H6 promoter and the entire PRVgpII gene was generated by this digestion. The 2.8 Kb EcoRV/Hindlll fragment was isolated for insertion in pFPCV2 (FIGS. 8,26).

The 2.8 Kb EcoRV/Hindlll fragment (defined above) was inserted into the 8.0 Kb pFPCV2 fragment derived by complete digest with Hindlll and partial digestion with

EcoRV. Ligation of these two fragments resulted in the formation of a 10.8 Kb plasmid designated as pFPPRVII.

Referring now to FIG. 27, plasmid pFPPRVII was utilized to generate a 2.8 Kb Nrul/Hindlll fragment for insertion into pCPCVl (FIG.9). The pCPCVl plasmid contains the W H6 promoter in the unique EcoRI site within the 3.3 Kb PvuII CP genomic fragment. This insertion plasmid enables the insertion of foreign genes into the C3 locus of the CP genome. The plasmid pCPCVl was digested with Nrul and Hindlll and the 5.8 Kb fragment was isolated for ligation to the 2.8 Kb fragment defined above. The

resultant plasmid was designated pCPPRVII.

The dominant selectable marker E. coli xanthineguanine phosphoribosyl transferase (Eco gpt) was inserted into pCPPRVII as a means of growth selection for CP/PRVgpII recombinants. Previous reports have described the use of Eco gpt as a selectable marker in the generation of poxvirus recombinants (193,194). The Eco gpt gene was obtained from the plasmid pSV2gpt (ATCC #37145). The 670 bp Bglll/Dral fragment, containing the Eco gpt gene, was isolated from this plasmid and inserted into the Bglll/Smal site of

PSD486VC. The resulting plasmid, pGPT-1, contains the Eco gpt gene between the W μ gene flanking arms and under the transcriptional regulation of the μ promoter. The plasmid PSD486VC was derived from pSD478VC (FIG.24) in the following manner. pSD478VC was digested with EcoRI in the MCR, filled in by Klenow standard reaction in the presence of dNTP (0.5 mM each) and religated to produce pSD478E VC. This plasmid was digested with Hpal and BamHI and annealed

oligonucleotide HEM 5 (5'-GATCCGATTCTAGCT-3') and HEM 6 (5'- AGCTAGAATCG-3') were inserted to produce pSD486VC.

Digestion of pGPT-1 with Ncol and EcoRI liberated a 1.0 Kb fragment containing the Eco gpt gene (670 bp) and the W μ promoter (330 bp). The Ncol and EcoRI ends were blunted using the Klenow fragment from the E. coli DNA polymerase in the presence of 0.5 mM dNTPs. Hindlll linkers (Bethesda Research Laboratories, Bethesda, MD) were added to the blunt-ended fragment. The DNA was digested with Hindlll and the 1.0 Kb fragment recovered from an agarose gel. This 1.0 Kb Hindlll fragment was then inserted into the Hindlll site of pCPPRVII. The resultant plasmid containing the Eco gpt and PRVgpII genes linked in a tail to tail configuration was designated as pCPPRVII gpt. This plasmid was used in in vitro recombination experiments for insertion into the C3 locus of the CP genome. Selection of recombinants

containing the Eco gpt gene were done in the presence of 100 μg/ml mycophenolic acid and the Eco gpt-positive

recombinants were subsequently screened for the presence of the PRVgpII gene by plague hybridization analyses. Eco gpt and PRV gpll positive plaques were purified by three cycles of plaque isolation and pure populations grown to high titer and designated as pCP55. Southern blot analyses confirmed that these two genes were indeed genetically linked in these CP recombinants. The CP recombinant was designated as VCP55. Immunofluorescence of vCP55 infected cells.

Immunofluorescence studies were performed to demonstrate the cellular localization of the expressed PRV gpll in VCP55 infected cells. CEF or PK-1 cells were seeded on 22 mm glass coverslips in 35 mm dishes at 5 x 10⁵ cells/dish. CEF and PK-1 cells were infected with either VCP55 or the CP parental virus. Infections and incubations for the

immunofluorescence assay were performed as described in Example 1, using monoclonal antibody 75N10, diluted 1 to 100 in PBS+.

The infected cells were analyzed for both internal and surface expression. No significant surface expression of gpll was observed in either cell system infected with vCP55. Internal expression of the gpll gene product was, however, demonstrated in both VCP55 infected CEF cells and PK-1 cells. The internal fluorescence signals in both cell types were localized to granules in the perinuclear region of the infected cells. These results suggest that the

PRVgpII expressed by CP is trafficked to the golgi complex but not to the plasma membrane. This result differs from the results with vaccinia virus expressed gpll which was detected on the surface of infected cells.

Immunoprecipitation of PRVgpII from CEF and PK-1 infected cells. Expression of the PRVgpII gene product by vCP55 was analyzed by immunoprecipitation from infected cell lysates. Cell monolayers were infected at 5 PFU/cell. The immunoprecipitation assay was performed as described in Example 1 using monoclonal antibody 75N10.

The predominant polypeptide species precipitated with rabbit anti-PRV serum from CEF and PK-1 infected cells migrated with apparent molecular weights of approximately 120 kDa, 67 kDa, and 58 kDa. These polypeptides represent the precursor and proteolytically processed forms,

respectively, of the PRVgpII detected in PRV infected cells that are complexed via disulfide linkages (86,101,196).

Minor species with apparent molecular weights of

approximately 26 kDa were also observed and may reflect further proteolytic processing events of gpll in these CP/PRV recombinant infected cells. No equivalent

polypeptides were precipitated from control CP virus

infected cell and uninfected cell lysates.

Protection studies. The ability for VCP55 to elicit a protective immune response against live PRV

challenge was analyzed in the mouse system. Mice were inoculated in the footpad with 50 ul to 100 ul samples containing various doses of vCP55 shown in Table 10.

Fourteen days following immunization the mice received 16 LD₅₀ of the Kojnock strain of PRV by the intraperitoneal route. Survivors were counted 14 days after challenge at which point the experiment was concluded. As demonstrated in Table 10, inoculation of mice with a single dose of 10^6.85 TCID₅₀ protected eight out of ten mice from a lethal

challenge of PRV. The lower doses of VCP55 tested did not afford any level of protection. Challenge with live PRV killed seven out of eight unvaccinated mice. From the results presented in Table 10, a PD50 (protective dose 50%) was calculated to be 10^6.16 for the VCP55 recombinant.

The efficacy of VCP55 as an immunizing agent against live PRV challenge was also evaluated in the target species, the piglet. Fifteen piglets weighing nearly 25 kg were separated into three groups. The vCP55 group and the CP parental virus group each received two inoculations (2 ml equaling 2x10⁸ TCID₅₀) on days 0 and 28 by the intramuscular route. Five piglets were left as unvaccinated controls.

All piglets were administered the pathogenic NIA3 strain of PRV by the intranasal route on day 35. Efficacy was

monitored by comparing the weight evolution of VCP55

vaccinated and control pigs during the seven days post challenge. Weight evolution is calculated as Delta GMQR Values (in kilograms) = mean GMQR % vaccinated piglets - mean GMQR % unvaccinated piglets.

In the unvaccinated group, all piglets succumbed to the PRV virus challenge (two on day five, two on day six, and one on day seven). In the wildtype virus (CP)

inoculated groups four of the five piglets succumbed to challenge (three on day six, one on day seven). All the piglets in the vCP55 vaccinated group survived PRV challenge and thrived.

Significant levels of protection for piglets inoculated with vCP55 expressing the PRVgpII glycoprotein against live PRV challenge was observed (Table 11). vCP55 vaccinated animals had a significant net weight gain over the experimental period, whereas the two control groups had a significant weight loss over the period following PRV challenge. Additionally, no deaths were observed in the vCP55 vaccinated group, while an 80% to 100% mortality rate was noted in the control groups following live PRV

challenge.

m

Example 12 - VACCINIA RECOMBINANTS EXPRESSING PRV gI

GLYCOPROTEINS

The Copenhagen strain of vaccinia virus and recombinants derived therefrom were utilized in this

example.

Cloning of the PRVgl gene into canary pox and vaccinia virus donor plasmids. Referring now to FIG. 28, a plasmid pGPI containing the PRVgl gene (NIA3 strain) was obtained from Rhone Merieux, Lyon, France. The gl gene (sequence reference (80)) was isolated from this plasmid and cloned downstream of the vaccinia synthetic H6 promoter (69). This was accomplished by cloning the 2,330 bp Xhol- Ncol (partial) fragment of pGPI into the 6,400 bp Xhol-Ncol fragment of pGBC2. (pGBC2 was generated by cloning the HSV2 gB gene into the 3,200 bp Bglll fragment of pRW764.5.

pRW764.5 was constructed by cloning a 0.8 Kb PvuII fragment from canarypox DNA into the 2,360 bp PvuII fragment of pUC18.) The plasmid generated by this manipulation is designated pPGI2.

The initiation codon of the H6 promoter was then aligned with the initiation codon of the gl gene. This was accomplished by cloning the oligonucleotides, PRVL5 5'- ATCCGTTAAGTTTGTATCGTAATGCGGCCCTTTCTGCTGCGCGCCGCGCAGCTC-3 ' and PRVL6 5'- CTGCGCGGCGCGCAGCAGAAAGGGCCGCATTACGATACAAACTTAACGGAT-3 ', into the 5,900 bp EcoRV-AlwNI (partial) fragment of pPGI2. The plasmid generated by this manipulation is designated pPG13.

Extraneous PRV gl 3'-noncoding sequences were then eliminated. This was accomplished by cloning the

oligonucleotides, PRVL3 5'-

CTGGTTCCGCGATCCGGAGAAACCGGAAGTGACGA

ATGGGCCCAACTATGGCGTGACCGCCAGCCGCCTGTTGAATGCCCGCCCCGCTTAACTGC AGAATTCGGATCCGAGCT-3' and PRVL4 5'- CGGATCCGAATTCTGCAGTTAAGCGGGGC GGGCATTCAACAGGCGGCTGGCGGTCACGCCATAGTTGGGCCCATTCGTCACTTCCGGTT TCTCCGGATCGCGGAACCAGACGT-3', into the 5,200 bp Sacl-Aatll (partial) fragment of pPGI3. The plasmid generated by this manipulation is designated pPG16. The H6 promoted gl gene was then cloned into a vaccinia virus donor plasmid. This was accomplished by cloning the 1,750 bp Nrul-BamHI fragment of pPGI6 into the 5,000 bp Nrul-BamHI fragment of pBP14. (pBP14 contains the Bovine leukemia virus gag gene under the control of the synthetic vaccinia H6 promoter in vaccinia vector plasmid pSD494VC. pSD494VC is a subclone of the Copenhagen vaccinia virus Hindlll A fragment in which the coding sequence of the vaccinia gene containing homology to the cowpox ATI gene (210) is replaced by a polylinker region.) This places the H6 promoted gl gene between the vaccinia virus (Copenhagen) sequences flanking the ATI gene. The plasmid generated by this manipulation is designated pPGI7.

The recombinant vaccinia virus vP717 was generated by transfecting pPGI7 into vP410 infected cells.

Construction of vP717. The gl gene of PRV was cloned into a vaccinia virus vector. The strategy used to construct this vaccinia virus recombinant, vP717, is

outlined in FIG. 28. The PRVgl gene contained in vP717 is cloned between the vaccinia virus sequences flanking the ATI gene and utilizes the vaccinia virus early-late promoter, H6 (41,42,69).

Immunofluorescence of the PRV-encoded polypeptide on vP717 infected cells. In PRV infected cells, gl is expressed on the plasma membrane. Immunofluorescence analyses of vP717 infected cells with the PRV gl-specific monoclonal antibody, 42M17, indicate that the PRV encoded polypeptide produced in these cells is also expressed on the plasma membrane.

Evaluation of vP717 in mice. In vivo evaluation of vP717 in mice indicated some protection against PRV challenge (Table 12) using standard procedures. m m

Example 13 - EXPRESSION OF HERPES SIMPLEX VIRUS TYPE 2

GLYCOPROTEINS gB, gC AND gd IN VACCINIA VIRUS RECOMBINANTS EITHER INDIVIDUALLY OR IN COMBINATIONS HSV2 (strain G) (American Type Culture Collection,

Bethesda, MD) (ATCC #VR734) utilized in this example was propagated in VERO cells (ATCC #CCL81) and purified by centrifugation on a sucrose gradient (197).

Cloning of the HSV2 gB gene into vaccinia virus donor plasmids. The nucleotide sequence of the HSV2 gB gene has been previously published (116). Referring now to FIG. 29, a 12 Kb Bglll fragment containing the HSV2 gB gene was isolated from HSV2 (strain G) genomic DNA and inserted into the BamHI site of pUC19 generating the plasmid pJ4.

The gB gene was then cloned between vaccinia virus

(Copenhagen) flanking arms. This was accomplished by cloning the 2,700 bp Sstll-SacI (partial) fragment of pJ4 into the Sstll-SacI fragment of pMP409DVC3. (pMP409DVC3 is a derivative of pMP409DVC (184) (FIG.4) in which the Belli site is replaced by a polylinker region). This places the gB gene between the vaccinia sequences flanking the M2L gene. The plasmid generated by this manipulation is

designated pGBl.

An in-frame termination codon was then added to the 3' end of the gB gene. This was accomplished by cloning the oligonucleotides GBL3 5'-CTAATAG-3' and GBL4 5'- GATCCTATTAGAGCT-3 ' into the 6,300 bp BamHI-SacI (partial) fragment of pGBl. The plasmid generated by this

manipulation is designated pGB2.

The H6 promoter was then cloned upstream of the gB gene. This was accomplished by cloning the 370 bp Bglll fragment of pBLVH14 containing the H6 promoter into the Bglll site of pGB2 (pBLVH14 contains the H6 promoted bovine leukemia virus envelope gene in the vaccinia HA deletion locus). The plasmid generated by this manipulation is designated pGB3.

The initiation codon of the H6 promoter was then aligned with the initiation codon of the gB gene. This was accomplished by cloning the oligonucleotides, GBL1 5'- ATCCGTTAAGTTTGTATCGTAATGCGCGGGGGGGGCTTGATTTGCGCGCTGGTCGTGGGG GCGCTGGTGGCCGC-3' and GBL2 5'- GGCCACCAGCGCCCCCACGACCAGCGCGCAAATCA

AGCCCCCCCCGCGCATTACGATACAAACTTAACGGAT-3', into the 6,300 bp Sstll-EcoRV (partial) fragment of pGB3. The plasmid

generated by this manipulation is designated pGB5. In plasmid pGB5 the HSV gB gene is under the control of the vaccinia H6 promoter inserted into the M2L deletion locus of vaccinia. Since the M2L insertion locus is located within a larger region of the genome which can be deleted, the H6- promoted gB gene was cloned into a different insertion site in a different vaccinia virus donor plasmid. This was accomplished by cloning the 2,800 bp Bglll-BamHI fragment of pGB5 into the Bglll site of pSD513VCVQ. (pSD513VCVQ is a subclone of the Copenhagen vaccinia virus Hindlll J fragment in which the coding sequence for the thymidine kinase (TK) gene is replaced by a polylinker region). This places the H6-promoted gB gene between the vaccinia virus sequences flanking the TK gene. The plasmid generated by this

manipulation is designated pGB6.

Cloning of the HSV2 gC gene into vaccinia virus donor plasmids. The nucleotide sequence of the HSV2 gC gene has been previously determined (117). Referring now to FIG 30, a 2,900 bp Sall fragment containing the HSV2 gC gene was isolated from HSV2 (strain G) genomic DNA and inserted into the Sall site of pIBI25 generating the plasmid pGC3.

The gC gene was then cloned between vaccinia virus (Copenhagen) flanking arms. This was accomplished by cloning the 2,900 bp XhoI-BamHI fragment of pGC3 into the XhoI-BamHI site of pGC2. pGC2 was generated by cloning the 370 bp Bglll fragment of pBLVH14, containing the vaccinia virus H6 promoter into the Bglll site of pSD486VC. pSD486VC is a subclone of the Copenhagen vaccinia virus Hindlll B fragment in which the coding sequence of the μ gene is replaced by a polylinker region. This places the gC gene between the vaccinia virus sequence flanking the μ gene. The plasmid generated by this manipulation is designated pGC5. The initiation codon of the H6 promoter was then aligned with the initiation codon of the gC gene. This was accomplished by cloning the oligonucleotides,

GCL1 5'- ATCCGTTAAGTTTGTATCGTAATGGCCCTTGGACGGGTGGGCCTAGCCGTGGGCCTGTG- 3' and GCL2 5'-

AGGCCCACGGCTAGGCCCACCCGTCCAAGGGCCATTACGATACAAACTTAACGGAT-3', into the 5,400 bp Nrul-Sfil fragment of pGC5. The plasmid generated by this manipulation is designated pGC10.

Extraneous 3'-noncoding sequence was then eliminated from pGC10. This was accomplished by

recircularizing the E. coli DNA polymerase I (Klenow

fragment) treated 4,900 bp Sall-Smal (partial) fragment of pGC10. The plasmid generated by this manipulation is designated pGC11.

Additional 3'-noncoding sequence was then eliminated from pGCll. This was accomplished by cloning the oligonucleotide, GCL3 5'-CTAGGGCC-3', into the 4,900 bp

Xbal-Apal (partial) fragment of pGCll. The plasmid

generated by this manipulation is designated pGC12. In plasmid pGC12 the HSV gC gene is under the control of the H6 promoter inserted into the μ deletion locus of vaccinia. Since the μ insertion locus is located within a larger region of the genome which can be deleted, the H6-promoted gC gene was then cloned into the ATI insertion site in a vaccinia virus donor plasmid. This was accomplished by cloning the 1,550 bp NruI-BamHI fragment of pGC12 into the 5,000 bp NruI-BamHI fragment of pBP14. This places the H6- promoted gC gene between the vaccinia virus (Copenhagen) sequences flanking the ATI gene. The plasmid generated by this manipulation is designated pGC13.

Cloning of the HSV2 gD gene into vaccinia virus donor plasmids. The nucleotide sequence for the HSV2 gD gene has been previously determined (118). Referring now to FIG. 31, a 7.5 Kb Xbal fragment containing the HSV2 gD gene was isolated from HSV2 (strain G) genomic PNA and inserted into the Xbal site of pIBI25 generating the plasmid pGPI.

The gD gene was then cloned downstream of the H6 promoter and between vaccinia virus (Copenhagen) flanking arms. This was accomplished by cloning the 1,500 bp Dral- Pstl fragment of pGP1 into the Smal-PstI site of pTP15 (184) (FIG.3). This places the gD gene downstream of the H6 promoter and between the vaccinia virus sequences flanking the HA gene. The plasmid generated by this manipulation is designated pGP2.

The initiation codon of the H6 promoter was then aligned with the initiation codon of the gD gene. This was accomplished by cloning the oligonucleotides, GPL1 5'- ATCCGTTAAGTTTGTATCGTAATGGGGCGTTTGACCTCCGG-3' and GPL2 5'- CGCCGGAGGTCAAACGCCCCATTACGATACAAACTTAACGGAT-3', into the 5,100 bp EcoRV-Ahall (partial) fragment of pGP2. The plasmid generated by this manipulation is designated pGP5.

Extraneous 3'-noncoding sequence was then eliminated. This was accomplished by cloning the

oligonucleotides, GPL3 5'-

GGCAGTACCCTGGCGGCGCTGGTCATCGGCGGTATTGCGTTTTGGGTACGCCGCCGGCGC TCAGTGGCCCCCAAGCGCCTACGTCTCCCCCACATCCGGGATGACGACGCGCCCCCCTCG CACCAGCCATTGTTTTACTAGCTGCA-3' and GPL4 5'- GCTAGTAAAACAATGGCTGGTGCGAGGGGGGCGCGTCGTCATCCCGGATGTGGGGGAGAC GTAGGCGCTTGGGGGCCACTGAGCGCCGGCGGCGTACCCAAAACGCAATACCGCCGATGA CCAGCGCCGCCAGGGTACTGCC-3', into the 4,800 bp Nael-PstI fragment of pGP5. The plasmid generated by this

manipulation is designated pGP7.

Additional sequence was then added 5' to the H6 promoter. This was accomplished by cloning the 150 bp

Bglll-EcoRV fragment of pGB6 (FIG.30) into the 4,800 bp

Bglll-EcoRV fragment of pGP7. The plasmid generated by this manipulation is designated pGP8.

Construction of recombinant vaccinia viruses. The strategy used to clone the HSV2 gB, gC and gD genes into vaccinia virus is outlined in FIGS. 29, 30 and 31,

respectively. All constructs utilize the vaccinia virus early-late promoter, H6 (41,42,184). Each HSV2 gene, however, is cloned into a different site in the vaccinia virus genome. The H6-promoted gB gene is cloned between the sequence flanking the M2L gene (vP569) or the sequence flanking the TK gene (vP734, vP775 and vP776). The H6- promoted gC gene is cloned between the sequence flanking the μ gene (vP579) or the sequence flanking the ATI gene (vP748, vP776 and vP777). The H6-promoted gD gene is cloned between the sequence flanking the HA gene (vP570, vP761, vP775, and vP777). The recombinant vaccinia virus vP569 was generated by transfecting pGB5 into vP458 infected cells. vP734 was generated by transfecting pGB6 into vP618 infected cells. vP579 was generated by transfecting pGC11 into vP533

infected cells. vP748 was generated by transfecting pGC13 into vP618 infected cells. vP570 was generated by

transfecting pGP5 into vP425 infected cells. vP761 was generated by transfecting pGP8 into vP618 infected cells.

vP425 is a variant of wildtype vaccinia virus (Copenhagen) from which the TK gene has been deleted and the HA gene has been replaced by Beta-galactosidase (Example 1) (184). vP458 is a variant of wildtype vaccinia virus from which the TK gene has been deleted and the M2L gene has been replaced by Beta-galactosidase (Example 2). vP533 is a variant of wildtype vaccinia virus from which the TK gene has been deleted and the μ gene has been replaced by Beta- galactosidase. vP618 is a variant of wildtype vaccinia virus from which the TK, μ and ATI genes have been deleted.

Recombinant vaccinia virus containing two HSV2 glycoprotein genes were also constructed. vP775 contains the gB and gD genes, vP776 contains the gB and gC genes and vP777 contains the gC and gD genes. vP775 was generated by transfecting pGP8 into vP734 infected cells. vP776 was generated by transfecting pGC13 into vP734 infected cells. vP777 was generated by transfecting pGP8 into vP748 infected cells.

A recombinant vaccinia virus containing three HSV2 glycoprotein genes was also constructed. vP812 contains the gB, gC and gD genes of HSV-2. vP812 was generated by transfecting pGP8 into vP776 infected cells.

Immunofluorescence of HSV2 glycoproteins in recombinant vaccinia virus infected cells . In HSV2 infected cells, gB, gC and gD (as well as other HSV2 encoded

glycoproteins) are expressed on the plasma membrane.

Immunofluorescence studies performed on cells infected with the recombinant vaccinia viruses containing HSV2 genes indicate that the HSV2 polypeptides produced in cells infected with these recombinant vaccinia viruses are also expressed on the plasma membrane.

Immunoprecipitation of HSV2 glycoproteins in recombinant vaccinia virus infected cells. The HSV2 gB glycoprotein produced in HSV2 infected cells has a molecular weight of approximately 117 kPa (198,199). Cells infected with recombinant vaccinia viruses containing the HSV2 gB gene (vP569, vP734, vP775 and vP776) also produce a HSV2 encoded polypeptide with a molecular weight of approximately 117 kPa. Immunoprecipitation of vP569 infected cells with antisera to whole HSV2 virus precipitates two major proteins with molecular weights of approximately 117 kPa and 110 kPa and three minor proteins with molecular weights of 50 kPa, 45 kPa and 30 kPa. Immunoprecipitation of vP734, vP775 and vP776 infected cells precipitates two major proteins with molecular weights of approximately 110 kPa and 90 kPa and five minor proteins with molecular weights of approximately 117 kPa, 100 kPa, 50 kPa, 45 kPa and 30 kPa.

The HSV2 gC glycoprotein produced in HSV2 infected cells has a molecular weight of approximately 63 kPa

(199,200). Cells infected with recombinant vaccinia viruses containing the HSV2 gC gene (vP579, vP748, vP776 and Will) also produce a HSV2 encoded polypeptide with a molecular weight of approximately 63 kPa. Immunoprecipitation of vP579, vP748, vP776 and vP777 infected cells with antisera to whole HSV2 virus precipitates a major protein with a molecular weight of approximately 65 kPa and a minor protein with a molecular weight of approximately 85 kPa. Rabbit antisera against whole HSV2 virus was obtained from PAKO

Corporation (Santa Barbara, CA; code no. B116) and used at a dilution of 1:100.

The HSV2 gD glycoprotein produced in HSV2 infected cells has a molecular weight of approximately 51 kPa

(198,199). Cells infected with recombinant vaccinia viruses containing the HSV2 gD gene (vP570, vP761, vP775 and Will) also produce a HSV2 encoded polypeptide with a molecular weight of approximately 51 kPa. Immunoprecipitation of vP570, vP761, vP775 and vP777 infected cells with antisera to whole HSV2 virus precipitates a major protein with a molecular weight of approximately 48 kPa and two minor proteins with molecular weights of approximately 40 kPa and 31 kPa.

In vivo evaluation. All the recombinant vaccinia viruses expressing the various constructions of HSV2

glycoproteins protected immunized mice from subsequent lethal HSV challenge in experiments similar to those

described by Paoletti et al. (26).

Example 14 - EXPRESSION OF THE BOVINE HERPES VIRUS 1

GLYCOPROTEIN gI IN VACCINIA VIRUS RECOMBINANTS Cloning of the BHV1 gl gene into vaccinia virus donor plasmids. The nucleotide sequence of the BHVl gl gene has been previously published (63). Referring now to FIG. 32 a plasmid pIBRS6 containing the BHVl gl gene (Straub strain) was obtained from Rhone Merieux, Lyon, France. The 5' end of the gl gene was cloned downstream of the H6 promoter (41,42,69) and between vaccinia virus (Copenhagen) flanking arms. This was accomplished by cloning the 540 bp Sall-PstI fragment of pIBRS6 into the 4,400 bp Sall-PstI fragment of pGP5 (pGP5 was generated by cloning the HSV2 gD gene into pTP15 (184) (FIG.3). This places the gl gene downstream of the H6 promoter and between vaccinia virus HA flanking arms. The plasmid generated by this manipulation is designated pIBR2.

The initiation codon of the H6 promoter was then aligned with the initiation codon of the gl gene. This was accomplished by cloning the oligonucleotides,

IBRL1 5'- ATCCGTTAAGTTTGTATCGTAATGGCCGCTCGCGGCGGTGCTGAACGCGCCGC-3^, and IBRL2 5'-

GGCGCGTTCAGCACCGCCGCGAGCGGCCATTACGATACAAACTTAACGGAT-3', into the 3,800 bp Nrul-Sstll fragment of pIBR2. The plasmid generated by this manipulation is designated pIBR4.

An Ncol site, necessary for future manipulations, was then generated. This was accomplished by cloning the oligonucleotides IBRL3 5'-CCATGGTTTAATGCA-3' and IBRL4 5'- TTAAACCATGGTGCA-3' into the PstI site of pIBR4. The plasmid generated by this manipulation is designated pIBR5. The 3' end of the gl gene was then cloned into pIBR5. This was accomplished by cloning the 1,740 bp

Tth111l-Ncol fragment of pIBRS6 into the 3,700 bp Tth111l- Ncol fragment of pIBR5. The plasmid generated by this manipulation is designated pIBR7.

A Bglll site necessary for future manipulations was then generated. This was accomplished by cloning the oligonucleotides IBRL5 5'-CATGGTTTAAGATCTC-3' and IBRL6 5'- CATGGAGATCTTAAAC-3', into the Ncol site of pIBR7. The plasmid generated by this manipulation is designated pIBR8.

A portion of the long hydrophilic leader sequence of the gl gene was then deleted (63). This was accomplished by cloning the oligonucleotides, IBRL7 5'- ATCCGTTAAGTTTGTATCGTAATGGCCGCGCTAGCCGCTGCCCTGCTATGGGCGACGTGG GCC-3' and IBRL8 5'-

CACGTCGCCCATAGCAGGGCAGCGGCTAGCGCGGCCATTACGATACAAACTTAACGGAT- 3', into the 4,400 bp Nrul-Apal (partial) fragment of pIBR8. This eliminates 132 bp of the hydrophilic leader sequence. The plasmid generated by this manipulation is designated pIBR9.

The H6 promoted truncated gl gene was then cloned into a different vaccinia virus donor plasmid. This was accomplished by cloning the 1,700 bp Nrul-Bglll fragment of pIBR9 into the 4,900 bp NruI-BamHI fragment of pBP14 (211). The plasmid generated by this manipulation is designated PIBR10.

Construction of recombinant vaccinia viruses. The strategy used to clone the BHVl gl gene into vaccinia virus is outlined in FIG. 32. The recombinant vaccinia virus vP637 was generated by transfecting pIBR7 into vP410 infectded cells. vP724 was generated by transfecting pIBR10 into vP410 infected cells. vP637 contains the entire BHVl gl gene. vP724 contains a gl gene deleted of 132 bp of 5' signal sequence (63). Both constructs utilize the vaccinia virus early-late promoter, H6 (41,42,184). The gl gene in vP637 is cloned between the sequences flanking the HA gene. The gl gene in vP724 is cloned between the sequences flanking the ATI gene. Immunofluorescence and detection of a BHVl-encoded polypeptide in recombinant vaccinia virus infected cells. In BHV1 infected cells gl is expressed on the plasma

membrane. Immunofluorescence studies of cells infected with vP637 or vP724 indicate that the BHVl encoded polypeptide produced in these cells is also expressed on the plasma membrane. Immunofluorescence was performed as described in Example 1. The BHV1 gl-specific monoclonal antibodies, 4203 and 5106, were used (201).

Example 15 - EXPRESSION OF FELINE HERPESVIRUS GLYCOPROTEIN gB IN A VACCINIA VIRUS RECOMBINANT

The WR strain of vaccinia virus (202) was utilized in this example. The WR strain derived recombinant vaccinia virus vP293 was used as a rescuing virus (69).

Extraction of FHV-1 DNA and cloning of the FHV-1

SacI-SacI 3.2 Kb fragment. FHV-1 DNA was extracted and purified from the C O strain. The FHV-1 DNA genome was digested with EcoRI and ligated in plasmid pBR322 using standard procedures (20). This FHV-1 bank was screened with DNA probes derived from the PRVgll (62) and BHV-1 gB (203) genes. Subsequent hybridizations with subclones derived from the two EcoRI clones found positive by hybridization allowed more accurate mapping of the FHV-1 gB gene. A 3.2 Kb SacI-SacI fragment containing the FHV-1 gB gene was cloned into pUC18, thus generating plasmid pFHVgBC.

Sequencing of the SacI-SacI fragment encoding FHV- 1 gB. Nucleotide sequence data for both strands were obtained from pFHVgBC and pFHVgBC-derived subclones using modified T7 Sequenase as described above.

Cloning of the FHV-1 gB gene into a vaccinia virus donor plasmid. Referring now to FIG. 33, the FHV-1 gB gene was cloned in pHES4, one of the plasmids designed for the host range selection system in WR vaccinia virus strain (69) (FIG.10). This plasmid bears the host range gene KIL which allows the deletion mutant vP293 to replicate on human cells. The FHV-1 gB gene was inserted immediately

downstream from the vaccinia synthetic H6 promoter (69). Plasmid pFHVgBC was digested with Kpnl and SacI and the 3150 bp restriction fragment containing FHV-1 gB was isolated from an agarose gel and then ligated into plasmid pHES4 previously digested with Kpnl and SacI. The resulting plasmid was designated pJCA001 (FIG. 33).

DNA sequence analysis of the FHV-1 gB gene.

Referring now to FIG. 34, DNA sequence analysis revealed an open reading frame extending from nucleotide positions 337 to 3177. Putative transcriptional regulatory signals were found in the region 5' to the ATG initiation codon at position 337. A TATA box having the sequence AAATATAT

(nucleotides 184 to 191) was located 80 nucleotides

downstream from a putative CAT box having the sequence

GGTGAGTA. A polyadenylation signal AATAAA (nucleotides 3251 to 3256) was located 50 nucleotides downstream from the TAA termination codon (nucleotides 3178 to 3180). Eight out of 11 nucleotides in the sequence 5' TCATTCTAGCA 3'

(nucleotides 200 to 210) are complementary to the 18S ribosomal RNA sequence 3' AGGAAGGCGT 5' (61) and may serve as the ribosome binding site. A scanning model has been proposed by which eukaryotic mRNAs initiate translation (151,155). The sequence context around the proposed

initiation codon ATCATGT (nucleotides 334 to 340) qualifies as a functional sequence context for translation initiation of eukaryotic mRNA. The FHV-1 gB open reading frame encodes 947 amino acids with a calculated molecular mass of 106.2 kDa. The G + C content is 45.8%.

Analysis of the FHV-1 gB protein structure.

Analysis of the amino acid sequence revealed a number of features common to membrane associated glycoproteins. A region extending from amino acids 23 to 73 had a

characteristic hydrophobicity profile and is proposed to be the signal sequence (FIG. 34). Referring now to FIG. 35, there is a 22 amino acids long hydrophilic sequence

preceding the long hydrophobic signal sequence. This characteristic has also been noted for the pseudorabies (PRV) gll gene (62), for the bovine herpesvirus-1 (BHV-1) gl gene (63) and for the equine herpesvirus-1 (EHV-1) (71) and equine herpesvirus-4 (EHV-4) (72) gp14 genes, all of which are also HSV gB homologs. A hydrophobic region consisting of 42 amino acids (amino acids 789 to 831) is predicted to function as a transmembrane anchor domain. The hydrophilic cytoplasmic domain contains 116 amino acids. There are ten Asn-X-Thr/Ser (where X can be any amino acid except proline) sites for potential N-linked glycosylation (64), one site being located in the signal sequence. There are two

consecutive and close potential proteolytic cleavage sites (Arg-Arg-Ser) (positions 504 to 506 and 516 to 518)

identical to those present in PRVgll (94), VZV gpll and HCMV gB (71) and EHV-1 gp14 (71,72). The hydrophobicity profile of the FHV-1 gB amino acid sequence is shown in FIG. 35.

Comparison of the FHV-1 gB amino acid sequence to other herpesvirus glycoproteins. Comparison of the amino acid composition of the FHV-1 gB gene revealed extensive homology with glycoproteins of other herpesviruses. Thus the FHV-1 gB is homologous to PRVgll (62), BHV-1 gl (63), varicella zoster virus (VZV) gll (66,204), HSV-1 gB (67), HSV-2 gB (205), EHV-1 gp14 (71), as well as to glycoproteins in Epstein-Barr virus (EBV) (68,206) and human

cytomegalovirus (HCMV) (10).

Construction of the vaccinia recombinant vP713 expressing the FHV-1 gB glycoprotein. The FHV-1 gB coding sequences were inserted into a vaccinia virus vector using the WR vaccinia virus host range selection system

pHES4/vP293 (69). The ability of recombinant vaccinia progeny generated by recombination using the WR vaccinia virus vP293/pHES host range selection system to plaque on human MRC-5 cells permits rapid identification of these recombinants (69). Vaccinia virus recombinant vP713 was obtained by recombination performed with plasmid pJCA001 as donor plasmid and vP293 as rescuing virus (FIG. 33).

Immunofluorescence of FHV-1 gB glycoprotein synthesized by vP713. Immunofluorescence of recombinant vaccinia virus vP713 infected VERO and MRC-5 cells was performed as described in Example 1, using anti-FHV-1 gB specific sheep serum #2854. A multiplicity of infection of two pfu per cell was used. FITC donkey anti-sheep IgG was used as the second antibody.

FHV-1 gB was detectable on the surface of VERO cells infected with vaccinia recombinant vP713 as well as internally after acetone fixation. No significant internal or surface immunoreactivity toward FHV-1 gB was seen in vP410 infected control cells.

Immunoprecipitation of FHV-1 gB glycoprotein synthesized by vP713. In order to assess the FHV-1 gB glycoprotein expressed by vP713, VERO cells were infected with vP713 and proteins were metabolically labeled with ³⁵S methionine. Immunoprecipitations were performed with the radiolabeled cell lysates using anti-FHV-1 gB specific sheep serum #2854.

VERO cell monolayers seeded at 2 x 10⁶ cells per 60 mm dishes were infected at a low multiplicity of

infection of 0.1 pfu per cell with control (vP410) or recombinant vaccinia virus vP713. Immunoprecipitations were performed as described in Example 1.

No significant products are immunoprecipitated by the specific anti-FHV-1 gB serum from either uninfected VERO cells or VERO cells infected with the control vaccinia virus vP410. FHV-1 gB radiolabeled products were precipitated by serum #2854 from VERO cells infected with vP713. Five dominant metabolically radiolabeled polypeptides are specifically precipitated. The two larger polypeptides of apparent molecular sizes 115 kDa and 110 kDa, could

correspond to the non-glycosylated precursor and mature proteins (theoretical sizes respectively of 106 kDa and 98 kDa). A large band at 68 kDa could represent the two glycosylated subunits (69 kDa + 66 kDa) resulting from the proteolytic cleavage of a glycosylated precursor (136 kDa) which is lacking here. Three smaller precipitated products (59, 53 and 48 kDa) do not correspond to any known FHV-1 gB products and may represent degradation products. Examole 16 - CLONING AND EXPRESSION OF EPSTEIN-BARR VIRUS GLYCOPROTEIN IN POXVIRUS VECTORS

Cloning of the EBV gp340 and gp220 genes into the vaccinia donor Plasmid PMP409DVC. In this example, the EBV genes were isolated from the B95-8 EBV strain (207), the gp340 and gp220 genes were cDNA clones (plasmids pMLPgp340 and pMLPgp220, respectively), and the gB, gH and BBRF3 genes were isolated from a BamHI genebank. Referring now to FIG. 36, a 2100 bp Xmal-Clal fragment of pMLPgp220 plasmid was cloned into M13mp18 digested with Xmal-AccI. The phage obtained by this manipulation was designated mp18gp220 (FIG. 36). By in vitro mutagenesis (17) using the

oligonucleotides CM4

(TAAAGTCAATAAATTTTTATTGCGGCCGCTACCGAGCTCGAATTCG) and CM5 (GCTTGCATGCCTGCAGATATCCGTTAAGTTTGTATCGTAATGGAGGCAGCCTTGC) the gp220 gene was modified to be expressed under the control of the vaccinia H6 promoter. The plasmid containing the modified gp220 gene was designated mplδgp220(5+4) (FIG. 36).

The modified gp220 gene was cloned into the plasmid SP131NotI which contains the complete H6 synthetic promoter (69). This was accomplished by cloning the 2300 bp Narl-EcoRV fragment of mp18gp220(5+4) into the 2940 bp

EcoRV-NarI fragment of SP131NotI plasmid. The resulting plasmid was designated SP131gp220 (FIG. 36).

The gp340 gene under the control of the H6

promoter was obtained by cloning a 2360 bp Scal-Xhol

fragment of pMLPgp340 into the Xhol-Scal (partial) digested SP131gp220 plasmid. The resulting plasmid was designated SP131gp340 (FIG. 36).

The H6 promoted gp340 and gp220 genes were cloned into the vaccinia virus M2L insertion locus plasmid

pMP409DVC (FIG.4; in FIG. 36, 40 this plasmid is designated MP409). This was accomplished by cloning the 2S00 bp Mung- Bean nuclease treated NotI fragment of the plasmid

SP131gp340 and the 2100 bp Mung-Bean nuclease treated NotI fragment of the plasmid SP131gp220 into the Bglll Mung-Bean nuclease treated site of the plasmid pMP409DVC. The resulting plasmids were designated 409H6340 and 409H6220 respectively (FIG. 36).

Cloning of the EBV gB gene into the vaccinia virus donor plasmid pMP409DVC. Referring now to FIG. 37, a 3500 bp EcoRI-XmnI fragment of the EBV DNA BamHI A fragment

(207), containing the EBV gB gene, was isolated from the EBV genomic library and cloned into the 2837 bp HincII-EcoRI fragment of pIBI25. The resulting plasmid was designated p25gB (FIG. 37).

By in vitro mutagenesis (17,165) using the oligonucleotides EBVBM5

(CCCTACGCCGAGTCATTACGATACAAACTTAACGGATATCAGAGTCGTACGTAGG) and EBVBM3

(CTGGAAACACTTGGGAATTCAAGCTTCATAAAAAGGGTTATAGAAGAGTCC), the gB gene was adapted to be expressed under the control of the vaccinia H6 promoter. The resulting plasmid was designated p25gB(5+3).

The 2600 bp EcoRV-EcoRI fragment of p25gB(5+3) was cloned into the 3300 bp EcoRV-EcoRI fragment of SP131. The resulting plasmid was designated SP131gB (FIG. 37).

The H6 promoter gB gene was then cloned into the vaccinia virus donor plasmid pMP409DVC. This was

accomplished by cloning the 2700 bp Hindlll Mung-Bean nuclease treated fragment of SP131gB into the Bglll Mung- Bean nuclease treated site of pMP409DVC. The resulting plasmid was designated 409H6gB (FIG. 37).

Cloning of the EBV gH gene into the vaccinia donor plasmid pSD486VC. In the EBV BamHI cloned restriction fragments library, the open reading frame BXLF2 is contained in the BamHI X and BamHI T fragments (207). As shown in FIG. 38, the complete BXLF2 open reading frame was

reconstituted by cloning the 830 bp Smal-BamHI fragment of BamHI X into the 2880 bp Smal-BamHI fragment of pIBI24; the resulting plasmid was designated 24gH5. The 1850 bp BamHI- Hindlll fragment of BamHI T was cloned in the 3660 bp BamHI- Hindlll fragment of 24gH5. The resulting plasmid containing the complete gH gene was designated 24gH (FIG. 38).

By in vitro mutagenesis (17,185) using the

oligonucleotides HM5 (ACACAGAGCAACTGCAGATCTCCCGATTTCCCCTCT), HM4 (GGGCAAAGCCACAAAATATGCAGGATTTCTGCG) and HM3 (GCCAGGGTTTTCCCAGAGATCTGATAAAAACGACGGCCAGTG) the gH gene was modified to be expressed under the control of the vaccinia hemorrhagic (μ) early promoter. The oligonucleotide HM4 was used to remove a vaccinia early transcription stop signal contained into the gH gene (45). The plasmid containing the modified gH gene was designated 24gH(5+4+3).

Referring now to FIG. 38, the vaccinia μ promoter is contained into the plasmid, pSD486 VC (FIG.30). (In FIG.38, this plasmid is designated SD486). The 2130 bp

Bglll Mung Bean nuclease treated fragment of 24gH(5+4+3) was cloned into the Bglll Mung-Bean nuclease treated pSD486VC. This last cloning step put the gH gene under the control of the vaccinia μ promoter. The plasmid generated by this manipulation was designated 486gH (FIG. 38).

Cloning of the open reading frame BBRF3 into the vaccinia virus donor plasmid pCOPSC-5H. The complete BBRF3 open reading frame is contained in the BamHI B fragment of the EBV DNA. This fragment was digested by BspHI, treated by the E. coli DNA polymerase I (Klenow fragment) and digested by Bglll. The Bglll site within the BamHI A fragment is located 10 bases before the stop codon of BBRF3. The 1230 bp BspHI-Bglll fragment was isolated and cloned into the 4200 bp Smal-Bglll fragment of the plasmid pCOPSC- 5H. (Plasmid pCOPCS-5H is identical to plasmid pCOPCS657

(FIG.16)). The plasmid generated by this manipulation was designated COPSCEBVX.

Cloning of the EBV gp340, gB and gH genes into vaccinia virus donor plasmid pSD513VCVO. The vaccinia virus donor plasmid used to generate the triple EBV recombinant was the plasmid, pSD513VCVQ (FIG.29). This plasmid contains a subclone of the Copenhagen vaccinia virus Hindlll J fragment in which the coding sequence for the thymidine kinase gene is replaced by a polylinker region.

In a first step, the μ promoted EBV gH gene was cloned into pSD513VCVQ. In particular, the 2300 bp SnaBI- BglII fragment of 486gH was cloned into the 4000 bp Smal- Bglll fragment of pSD513VCVQ. The plasmid generated by this manipulation was designated 513UgH. Next, the H6 promoted EBV gp340 gene was cloned into 513gH. In particular, the 2800 bp NotI Mung-Bean treated fragment of SP131gp340 was cloned into the 6300 bp XhoI-PstI Mung-Bean nuclease treated fragment of 513UgH.

The plasmid generated by this manipulation was designated 513UgH340H6.

Then, the H6 promoted EBV gB gene was cloned into 513UgH340H6. In particular, the 2700 bp Hindlll Mung-Bean nuclease treated fragment of SP131gp340 was cloned into the 9100 bp Bglll Mung-bean nuclease treated fragment of

513UgH340H6. The resulting plasmid was designated

513gHgBgp340 (FIG.39).

Construction of recombinant vaccinia virus. EBV gp340 (donor plasmid 409H6340), EBV gp220 (donor plasmid 409H6220), and EBV gB (donor plasmid 409H6gB) were

recombined into the vaccinia virus vP458 (M2L site): these single vaccinia virus recombinants are designated vP474, vP480 and vP561, respectively. EBV gH (donor plasmid 486gH) was recombined into the vaccinia virus vP533 (μ insertion site): this single vaccinia virus recombinant is designated vP611.

Finally the triple vaccinia virus recombinant containing gp340, gB and gH was obtained by recombining the donor plasmid 513gHgBgp340 into the vaccinia virus vP617 at the thymidine kinase insertion site. This recombinant virus is designated vP712. vP617 is a Copenhagen vaccinia virus deleted for TK, HA and ATI genes.

Immunofluorescence of EBV proteins in recombinant vaccinia virus infected cells. Immunofluorescence studies performed on cells infected with vP474 (gp340) and vP480 (gp220) using the monoclonal antibody F29-89 (165) showed EBV gp340 and EBV gp220 proteins expressed on the plasma membrane.

Cells infected with vP611 (gH), using a human serum, showed a weak positive signal on the plasma membrane.

Finally, the same experiment was performed with cells infected with vP712 (triple EBV vaccinia recombinant): a positive signal on the plasma membrane was obtained with the monoclonal antibodies F29-89 and NEA 9247 (gB

specificity obtained from DuPont).

Immunoprecipitation of EBV proteins in recombinant vaccinia virus infected cells. The EBV gp340 glycoprotein produced in EBV infected cells has a molecular weight of approximately 340 kDa (165). Cells infected with the recombinant vaccinia viruses vP474 or vP712 also produce an EBV encoded protein of approximately 340 kDa

(immunoprecipitation performed with the monoclonal antibody F29-89). The EBV gp220 glycoprotein has a molecular weight of 220 kDa (165). Cells infected with the vaccinia

recombinant virus vP480 produce an EBV encoded protein of approximately 220 kDa.

The EBV gB glycoprotein produced in EBV infected cells has a molecular weight of 110 kDa to 125 kDa with a precursor form of 93 kDa (206,208). Cells infected with the recombinant vaccinia viruses vP561 or vP712 produce an EBV major protein with a molecular weight of approximately 125 kDa and four minor proteins with molecular weights of approximately 80 kDa, 60 kDa, 50 kDa and 45 kDa.

The EBV gH glycoprotein produced in EBV infected cells has a molecular weight of 85 kDa with a precursor form of 70 kDa (209). Cells infected with the recombinant virus vP611 produce an EBV encoded protein of approximately 85 kDa.

Immunization of rabbits with vaccinia recombinants expressing EBV glycoproteins. Rabbits were immunized with vP474 (gp340) or vP480 (gp220) or vP561 (gB) or vP611 (gH) or vP712 (triple). After one boost the sera were tested by immunofluorescence on TPA treated B95-8 cells. Positive signals were obtained in each case. In vitro neutralizing activity was demonstrated using the sera raised against vP474 (gp340).

Example 17 - CLONING AND EXPRESSION OF HUMAN CYTOMEGALOVIRUS

GLYCOPROTEIN ANTIGENS IN POXVIRUS VECTORS

Cloning of the HCMV gB gene into the vaccinia donor plasmid pMP409DVC. Referring now to FIG. 40, the 4800 bp Hindlll-BamHI fragment of the Hindlll D fragment of the HCMV DNA was cloned into the 2800 bp Hindlll-BamHI fragment of the plasmid pIBI24. By in vitro mutagenesis (17,185) using the oligonucleotides CMVM5

(GCCTCATCGCTGCTGGATATCCGTTAAGTTTGTATCGTAATGGAATCCAGGATCTG) and CMVM3 (GACAGATTGTGATTTTTATAAGCATCGTAAGCTGTCA), the HCMV gB gene was modified to be expressed under the control of the vaccinia H6 promoter. The plasmid containing the modified HCMV gB gene was designated 24CMVgB(5+3) (FIG. 40).

Next, the 2900 bp EcoRV-BamHI fragment of 24CMVgB(5+3) was cloned into the 3100 bp EcoRV-Bqlll

fragment of plasmid pSP131 which contains the synthetic H6 promoter (69). This cloning step put the HCMV gB gene under the control of the vaccinia H6 promoter. The resulting plasmid was designated SP131gB.

Finally, the H6 promoted HCMV gB gene was cloned into the vaccinia donor plasmid pMP409DVC. The 3000 bp

Hindlll Mung Bean nuclease treated fragment of SP131gB was cloned into the Bglll Mung Bean nuclease treated site of pMP409DVC. The resulting plasmid was designated 409CMVgB (FIG. 40).

Construction of recombinant vaccinia virus. The

H6 promoted CMV gB gene in plasmid 409CMVgB was inserted into the M2L site of the rescue virus vP458. The

recombinant vaccinia virus was designated vP525.

Immunofluorescence of CMV gB protein in recombinant vaccinia virus infected cells.

Immunofluorescence studies on cells infected with vP525 using a monoclonal antibody or a guinea pig polyclonal serum showed HCMV gB expressed on the plasma membrane.

Immunoprecipitation of CMV gB in recombinant vaccinia infected cells. The CMV gB glycoprotein produced in CMV infected cells has a molecular weight of 55 kDa with a precursor form of 130 kDa (172). Cells infected with vP525 produce two CMV gB encoded proteins of approximately 130 kDa and 55 kDa.

Nucleotide sequences of HXLF1 and HXLF2. The HXLF gene family is localized in the Hindlll X fragment of the HCMV genomic DNA (172). Using specific oligonucleotide primers the nucleotide sequence of HXLF1 and HXLF2 have been determined (FIGS. 41, 42). HXLF1 is 648 nucleotides long and codes for a 215 amino acid protein. HXLF2 is 558 nucleotides long and codes for a 185 amino acid protein. The nucleotide seguences of the same genes (AD169 HCMV strain) have been published (173) and comparison studies show a 99% homology for HXLF1 and a 96% homology for HXLF2.

Immunization of guinea pigs with vaccinia recombinants expressing HCMV antigens. Three guinea pigs were immunized with vP525. After one boost, the animals developed HCMV neutralizing antibodies (mean titer: 518). Interestingly 50 to 87% of the neutralizing activity of HCMV seropositive human sera can be absorbed out by vP525

infected cells. This result indicates the potential

importance of HCMV gB as a subunit vaccine.

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Claims

WHAT IS CLAIMED IS:

1. A recombinant poxvirus containing therein DNA from equine herpesvirus in a nonessential region of the poxvirus genome.

2. A recombinant poxvirus as in claim 1 wherein said DNA codes for an equine herpesvirus glycoprotein.

3. A recombinant poxvirus as in claim 2 wherein said equine herpesvirus glycoprotein is equine herpesvirus glycoprotein gp13.

4. A recombinant poxvirus as in claim 2 wherein said equine herpesvirus glycoprotein is equine herpesvirus glycoprotein gp14.

5. A recombinant poxvirus as in claim 1 wherein said DNA codes for two equine herpesvirus glycoproteins.

6. A recombinant poxvirus as in claim 5 wherein said equine herpesvirus glycoproteins are equine herpesvirus glycoprotein gp13 and equine herpesvirus glycoprotein gp14.

7. A recombinant poxvirus as in claim 1 wherein said DNA is expressed in a host by the production of an equine herpesvirus glycoprotein.

8. A recombinant poxvirus as in claim 7 wherein said equine herpesvirus glycoprotein is equine herpesvirus glycoprotein gp13.

9. A recombinant poxvirus as in claim 7 wherein said equine herpesvirus glycoprotein is equine herpesvirus glycoprotein gp14.

10. A recombinant poxvirus as in claim 1 wherein said DNA is expressed in a host by the production of two equine herpesvirus glycoproteins.

11. A recombinant poxvirus as in claim 10 wherein said equine herpesvirus glycoproteins are equine herpesvirus glycoprotein gp13 and equine herpesvirus glycoprotein gp14.

12. A recombinant poxvirus as in claim 1 wwerein the poxvirus is a vaccinia virus.

13. A recombinant poxvirus as in claim 1 wherein the poxvirus is an avipox virus.

14. A recombinant poxvirus as in claim 13 wherein the avipox virus is selected from the group consisting of fowlpox virus and canarypox virus.

15. A recombinant poxvirus as in claim 1 wherein said DNA is introduced into said poxvirus by recombination.

16. A recombinant poxvirus containing therein DNA from equine herpesvirus and a promoter for expressing said DNA.

17. A vaccine for inducing an immunological response in a host animal inoculated with said vaccine, said vaccine comprising a carrier and a recombinant poxvirus containing, in a nonessential region thereof, DNA from equine herpesvirus.

18. A vaccine as in claim 17 wherein said DNA codes for and expresses an equine herpesvirus glycoprotein.

19. A vaccine as in claim 18 wherein said equine herpesvirus glycoprotein is equine herpesvirus glycoprotein gp13.

20. A vaccine as in claim 18 wherein said equine herpesvirus glycoprotein is equine herpesvirus glycoprotein gp14.

21. A vaccine as in claim 17 wherein said DNA codes for and expresses two equine herpesvirus

glycoproteins.

22. A vaccine as in claim 21 wherein said equine herpesvirus glycoproteins are equine herpesvirus

glycoprotein gp13 and eguine herpesvirus glycoprotein gp14.

23. A vaccine as in claim 17 wherein the poxvirus is a vaccinia virus.

24. A vaccine as in claim 17 wherein the poxvirus is an avipox virus.

25. A vaccine as in claim 24 wherein the avipox virus is selected from the group consisting of fowlpox virus and canarypox virus.

26. A vaccine as in claim 17 wherein said DNA is introduced into said poxvirus by recombination.

27. A recombinant poxvirus containing therein DNA from herpesvirus in a nonessential region of the poxvirus genome.

28. A recombinant poxvirus as in claim 27 wherein said herpesvirus is a member of a herpesvirus subfamily selected from the group consisting of alphaherpesvirus, betaherpesvirus and gammaherpesvirus.

29. A recombinant poxvirus as in claim 28 wherein said herpesvirus is selected from the group consisting of equine herpesvirus, pseudorabies virus, herpes simplex virus, bovine herpes virus, feline herpes virus, Epstein- Barr virus and human cytomegalovirus.

30. A recombinant poxvirus as in claim 27 wherein said DNA codes for a herpesvirus glycoprotein.

31. A recombinant poxvirus as in claim 30 wherein said herpesvirus glycoprotein is selected from the group consisting of equine herpesvirus gp13, equine herpesvirus gpl4, equine herpesvirus gD, equine herpesvirus gp63, equine herpesvirus gE, pseudorabies virus gp50, pseudorabies virus gpll, pseudorabies virus gpIII, pseudorabies virus gpl, herpes simplex virus gB, herpes simplex virus gC, herpes simplex virus gD, bovine herpes virus gl, feline herpes virus gB, Epstein-Barr virus gp220, Epstein-Barr virus gp340, Epstein-Barr virus gB, Epstein-Barr virus gH and human cytomegalovirus gB.

32. A recombinant poxvirus as in claim 27 wherein said DNA codes for at least two herpesvirus glycoproteins.

33. A recombinant poxvirus as in claim 27 wherein said DNA is expressed in a host by the production of a herpesvirus glycoprotein.

34. A recombinant poxvirus as in claim 33 wherein said equine herpesvirus glycoprotein is selected from the group consisting of equine herpesvirus gp13, equine

herpesvirus gp14, equine herpesvirus gD, equine herpesvirus gp63, equine herpesvirus gE, pseudorabies virus gp50, pseudorabies virus gpll, pseudorabies virus gpIII,

pseudorabies virus gpl, herpes simplex virus gB, herpes simplex virus gC, herpes simplex virus gD, bovine herpes virus gl, feline herpes virus gB, Epstein-Barr virus gp220, Epstein-Barr virus gp340, Epstein-Barr virus gB, Epstein- Barr virus gH and human cytomegalovirus gB.

35. A recombinant poxvirus as in claim 27 wherein said DNA is expressed in a host by the production of at least two herpesvirus glycoproteins.

36. A recombinant poxvirus as in claim 27 wherein the poxvirus is a vaccinia virus.

37. A recombinant poxvirus as in claim 27 wherein the poxvirus is an avipox virus.

38. A recombinant poxvirus as in claim 37 wherein the avipox virus is selected from the group consisting of fowlpox virus and canarypox virus.

39. A recombinant poxvirus as in claim 27 wherein said DNA is introduced into said poxvirus by recombination.

40. A recombinant poxvirus containing therein DNA from herpesvirus and a promoter for expressing said DNA.

41. A vaccine for inducing an immunological response in a host animal inoculated with said vaccine, said vaccine comprising a carrier and a recombinant poxvirus containing, in a nonessential region thereof, DNA from herpesvirus.

42. A vaccine as in claim 41 wherein said

herpesvirus is a member of a herpesvirus subfamily selected from the group consisting of alphaherpesvirus,

betaherpesvirus and gammaherpesvirus.

43. A vaccine as in claim 42 wherein said

herpesvirus is selected from the group consisting of equine herpesvirus, pseudorabies virus, herpes simplex virus, bovine herpes virus, feline herpes virus, Epstein-Barr virus and human cytomegalovirus.

44. A vaccine as in claim 41 wherein said DNA codes for and expresses a herpesvirus glycoprotein.

45. A vaccine as in claim 44 wherein said

herpesvirus glycoprotein is selected from the group

consisting of equine herpesvirus gp13, equine herpesvirus gp14, equine herpesvirus gD, equine herpesvirus gp63, equine herpesvirus gE, pseudorabies virus gp50, pseudorabies virus gpll, pseudorabies virus gpIII, pseudorabies virus gpl, herpes simplex virus gB, herpes simplex virus gC, herpes simplex virus gD, bovine herpes virus gl, feline herpes virus gB, Epstein-Barr virus gp220, Epstein-Barr virus gp340, Epstein-Barr virus gB, Epstein-Barr virus gH and human cytomegalovirus gB.

46. A vaccine as in claim 41 wherein said DNA codes for and expresses at least two herpesvirus

glycoproteins.

47. A vaccine as in claim 41 wherein the poxvirus is a vaccinia virus.

48. A vaccine as in claim 41 wherein the poxvirus is an avipox virus.

49. A vaccine as in claim 48 wherein the avipox virus is selected from the group consisting of fowlpox virus and canarypox virus.

50. A vaccine as in claim 41 wherein said DNA is introduced into said poxvirus by recombination.

51. A method for avoiding maternal immunity in a newborn offspring, which method comprises inoculating the newborn offspring with a recombinant poxvirus containing therein DNA from a non-pox source in a nonessential region of the poxvirus genome, said DNA coding for a first antigen of a pathogen of the newborn offspring, said antigen being different from a second antigen of the same pathogen used to induce an immunological response to the same pathogen in the mother of the newborn offspring.

52. A method for avoiding maternal immunity in a newborn offspring, which method comprises inoculating the newborn offspring with a recombinant first poxvirus

containing therein DNA from a non-pox source in a

nonessential region of the first poxvirus genome, said DNA coding for an antigen of a pathogen of the newborn

offspring, said first poxvirus being different from a recombinant second poxvirus used to induce an immunological response to the same pathogen in the mother of the newborn offspring.