Recombinant canarypox virus vaccine co-expressing genes encoding the VP2 and VP5 outer capsid proteins of bluetongue virus induces high level protection in sheep.

We describe the development and preliminary characterization of a recombinant canarypox virus vectored vaccine for protective immunization of ruminants against bluetongue virus (BTV) infection. Sheep (n=6) immunized with recombinant canarypox virus vector (BTV-CP) co-expressing synthetic genes encoding the two outer capsid proteins (VP2 and VP5) of BTV serotype 17 (BTV-17) developed high titers (40-160) of virus-specific neutralizing antibodies and were resistant to challenge with a field strain of BTV-17. In contrast, sheep (n=5) immunized with a commercial recombinant canarypox virus vector expressing the E and preM genes of West Nile virus were seronegative to BTV and developed pyrexia, lymphopenia, and extended, high-titered viremias following challenge exposure to the field strain of BTV-17. These data confirm that the BTV-CP vaccine may be useful for the protective immunization of ruminants against bluetongue, and it may avoid the problems inherent to live-attenuated (LA) BTV vaccines.