Enhanced production of Canine parvovirus VP2 protein using improved Baculovirus expression system and its immunogenicity

Background : Canine parvovirus (CPV) is now recognized as a serious threat to dog industry worldwide. Vaccination remains the principal tool to control CPV infection. However, due to low yield, production of VP2 protein of CPV in baculovirus expression system remains challenging. The aim of this study was to increase the VP2 protein production by using a improved baculovirus expression system (Multibac) and evaluate the immunogenicity of the purified VP2 protein in mice. Results: The results showed that CPV VP2 protein was successfully expressed in the improved baculovirus expression system efficiently. A high level of expression of the full length VP2 protein was achieved using our modified system. The recombinant virus carrying two copies of VP2 showed the highest expression level, with a productivity of 186 mg/L, which is about 1.4-1.6 fold that of the recombinant viruses carrying only one copy. The purified protein could react with Mouse anti-His tag monoclonal antibody and Rabbit anti-VP2 polyclonal antibody with good reactogenicity. The mice were then immunized with purified full length VP2 protein to evaluate its immunogenicity. After vaccination, VP2 protein could induce the mice produce high level of hemagglutination inhibition antibodies. Conclusions: Full length CPV VP2 protein was successfully expressed at high level and purified efficiently. And it stimulated mice to produce high level of antibody. The full length VP2 expressed in this study could be used as a putative economic and efficient subunit vaccine against CPV infection.