Induction of virus-neutralizing antibodies by immunization with Rachiplusia nu per os infected with a recombinant baculovirus expressing the E2 glycoprotein of bovine viral diarrhea virus

This work describes the development of a novel protein expression system based on Rachiplusia nu larvae for the production of the recombinant E2 protein to be used as a vaccine candidate against bovine viral diarrhea virus (BVDV). A recombinant baculovirus (Ac-E2pol+) bearing the E2 glycoprotein coding sequence of BVDV was obtained. Fourth-instar R. nu larvae were infected orally with recombinant polyhedra and the expression of E2 protein was confirmed by immunoblot. In order to test the recombinant product as a vaccine candidate, an immunization assay was performed and the neutralizing humoral immune response against BVDV NADL strain was evaluated. Mice vaccinated with Ac-E2pol+ extracts of per os infected larvae developed a neutralizing antibody titer of 3.16 after the administration of three doses of the immunogen. This report demonstrates the efficacy of per os infected larval extracts as a BVDV recombinant immunogen, which constitutes an easier and economic approach for producing recombinant antigens.