The present invention relates to infectious bovine rhinotracheitis viruses which fail to produce any functional thymidine kinase as a result of an insertion in the thymidine kinase gene, vaccines against infectious bovine rhinotracheitis containing the same and methods for production and use of same....http://www.google.com.au/patents/US5601816?utm_source=gb-gplus-sharePatent US5601816 - Infectious bovine rhinotracheitis virus insertion mutants, vaccines containing same, and methods for the production of same
