Immune response against the purified serotype specific antigen of bluetongue virus and initial attempts to clone the gene that codes for the synthesis of this protein.
Sheep were injected with different amounts of purified protein P2 of bluetongue (BT) virus (BTV). About 3 X 50 mcg was required for the induction of neutralizing antibodies. Sheep injected with 3 X 10 mcg were, however, still largely protected when challenged with virulent virus. This has suggested the possibility of using P2 as a subunit vaccine and initiated an investigation of the possibility of synthesizing P2 by DNA-recombinant technology. In order to clone the gene that codes for the synthesis of P2 both the "shotgun" approach with unfractionated dsRNA and cloning of isolated segment 2 were investigated. The basic approach was to convert the dsRNA to DNA which was cloned into the Pst 1 site of E. coli plasmid pBR322. The largest BTV-specific insert that was obtained in the initial experiments was just more than 2,000 base pairs long. The largest insert obtained when isolated segment 2 dsRNA was cloned was about 1,200 base pairs which represents about 1/3 of the P2 gene.