High level expression of the two outer capsid proteins of bluetongue virus serotype 10: their relationship with the neutralization of virus infection.

DNA representing RNA segments 2 and 5 of bluetongue virus (BTV) serotype 10, corresponding to the genes that code for the outer capsid proteins VP2 and VP5, have been inserted into a baculovirus transfer vector in lieu of the coding region of the polyhedrin gene of Autographa californica nuclear polyhedrosis virus (AcNPV). After co-transfection of Spodoptera frugiperda cells with wild-type AcNPV DNA in the presence of the recombinant transfer vector DNAs polyhedrin-negative recombinant baculoviruses were recovered. When S. frugiperda cells were infected with these recombinant viruses proteins of similar size and antigenic properties to BTV VP2 and VP5 were synthesised. The recombinant VP2, but not the recombinant VP5, was shown to be capable of inducing antibodies that neutralized the infectivity of BTV-10 in vitro.