38th Annual Meeting of the Society for Invertebrate Pathology

Using an approach we developed to express foreign proteins within baculovirus occlusion bodies (OBs), we expressed the influenza A nucleoprotein (NP) as a fusion between two copies of the polyhedrin protein at the polyhedrin locus of AcMNPV. Recombinant OBs with NP fusion protein were isolated and used to vaccinate mice. His-tagged soluble NP protein (His-NP), produced with conventional baculovirus expression technology, was used as a comparison for effectiveness of vaccination. The production of Ig antibodies, ratio of IgG2a to IgG1 antibodies produced, and lymphoproliferative response to NP challenge for excised lymph node cultures were measured and compared. His-NP protein (with adjuvant) gave a 10 fold better Ig titre than vaccination with NP-recombinant OBs. However, in lymphoproliferative assays, the NP-recombinant OBs gave a significantly higher stimulation index upon re-exposure to NP antigen than His-NP protein (with adjuvant). Additionally, vaccination studies showed that incorporation of foreign protein within OBs was more antigenic than simply co-injecting His-NP with wild-type OBs. Therefore, the ease of producing and isolating recombinant OBs which express good quantities of foreign protein, the stable nature of OBs, and the immune system stimulation by recombinant OBs all suggest that this approach could be a useful tool for vaccination of vertebrates.