DEVELOPMENT AND TRIAL OF A BOVINE HERPESVIRUS-1-THYMIDINE KINASE DELETION VIRUS AS A VACCINE

An Australian bovine herpesvirus 1 (BHV1) isolate with a defined (427 base pair) deletion in the protein coding region of the thymidine kina se gene was obtained by standard marker rescue procedures. After selec tion in the presence of the nucleotide analogue 5'-iodo-deoxy-uridine the virus was analysed by hybridisation with three differential oligon ucleotide probes, restriction endonuclease profile studies and DNA seq uence analysis. The virus elicited an immune response in recipient ani mals after either intramuscular or intravenous administration and prod uced no significant deleterious side-effects when administered at a do se sufficient to stimulate the host immune response. The safety and im munogenicity of the recombinant BHV1 virus 39B1 were similar to those reported for other registered BHV1 vaccines and the virus would appear to be suitable for the production of a vaccine seed lot and more exha ustive field trials as a prelude to commercial vaccine production and registration.