Development and trial of a bovine herpesvirus 1 ‐ thymidine kinase deletion virus as a vaccine

Abstract

An Australian bovine herpesvirus 1 (BHV1) isolate with a defined (427 base pair) deletion in the protein coding region of the thymidine kinase gene was obtained by standard marker rescue procedures. After selection in the presence of the nucleotide analogue 5'-iodo-deoxy-uridine the virus was analysed by hybridisation with three differential oligonucleotide probes, restriction endonuclease profile studies and DNA sequence analysis. The virus elicited an immune response in recipient animals after either intramuscular or intravenous administration and produced no significant deleterious side-effects when administered at a dose sufficient to stimulate the host immune response. The safety and immunogenicity 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 exhaustive field trials as a prelude to commercial vaccine production and registration.

The essential and non-essential genes of Bovine herpesvirus 1

“…Furthermore, the BoHV-1 genome encodes several genes for which there are no HHV-1 homologues. Genes that have been identified as non-essential for in vitro viability of BoHV-1 include the genes encoding glycoproteins C, E, I, G and M (Baranowski et al, 1996;Denis et al, 1996;Schwyzer & Ackermann, 1996;Tikoo et al, 1995), nucleotide metabolism genes encoding the thymidine kinase (Bello et al, 1992;Smith et al, 1994) and deoxyuridine triphosphatase proteins (Bello et al, 1992;Liang et al, 1993;Smith et al, 1994), as well as genes that encode tegument (UL49 and US9), membranous (UL49.5) (Liang et al, 1995(Liang et al, , 1993 and regulatory proteins such as the virion serine/threonine protein kinase (US3) (Furth et al, 1997), immediate-early transactivator protein (bICP0) (Geiser et al, 2005), immediate-early and late phase nuclear transrepressor protein (bICP22) and proteins putatively involved in immune evasion (Circ) (Fraefel et al, 1994;Furth et al, 1997;Schmitt & Keil, 1996). Genes of unknown function that are also identified as non-essential for BoHV-1 in vitro viability include those in US2, UL7 and UL24 ORFs (Furth et al, 1997;Schmitt & Keil, 1996;Whitbeck et al, 1994).…”

Construction and Manipulation of an Infectious Clone of the Bovine Herpesvirus 1 Genome Maintained as a Bacterial Artificial Chromosome

“…Briefly, REMR utilizes a unique NsiI restriction site (nucleotide position 63980 of the Cooper strain genomic sequence) to promote homologous recombination between BoHV-1 DNA and transgene DNA molecules. The NsiI site is located within the TK gene, which has previously been shown to be nonessential for in vitro and in vivo growth of the BoHV-1 strain V155 used in this study (26). Following NsiI digestion and dephosphorylation, if the BoHV-1 DNA is transfected into CRIB-1 cells, the two genomic segments do not produce infectious BoHV-1.…”

“…All of these reports have utilized conventional techniques based on eukaryotic homologous recombination, and while these techniques have been successful generally, only poor efficiencies have been achieved. These approaches have utilized homologous recombination of BoHV-1 genes in bovine cells for reduced virulence, such as deletion of the gene encoding thymidine kinase (TK) (11,26), or for the construction of marker vaccines through deletion of antigenic markers (10,30). Homologous recombination has also been used to insert gene expression cassettes into the genome of BoHV-1 to deliver antigens from other viruses and, more recently, immunomodulating molecules (12,17,18,22,29).…”

Recombinant Viral Vector Vaccines for the Veterinary Use.

“…Some of these conventional vaccines have sometimes caused several diseases, for example, abortion in cattle after vaccination for bovine herpesvirus type 1 (BHV-1) infection [102]. When such a case follows vaccination, it is important to differentiate the vaccine strain from field-type virus in order to exclude the possibility that natural infection may have occurred at the time of vaccination.…”

“…Such genetically engineered vaccines allow the possibility of identification of vaccine virus by probes for an inserted sequence or by PCR amplification across the deleted region [49,102,130]. However, it is still impossible to differentiate vaccinated animals from naturally infected animals.…”