Simultaneous expression of recombinant baculovirus-encoded chicken anaemiavirus (CAV) proteins VP1 and VP2 is required for formation of the CAV-specific neutralizing epitope

Chicken anaemia virus (CAV) expresses three proteins, VP1, VP2 and VP3, but its capsid contains only the VP1 protein. In this paper, we report that fo r production of the neutralizing epitope, cosynthesis of (recombinant) VP1 and VP2 has to take place. We show via immunofluorescence that recombinant- baculovirus-infected Sf9 cells synthesizing VP1 (or VP2) alone react very p oorly with CAV-specific neutralizing antibodies. in contrast, Sf9 cells co- infected with VP1- and VP2-recombinant baculo-viruses, or infected with a s ingle recombinant baculovirus co-expressing both VP1 and VP2, react strongl y with the neutralizing antibodies. Furthermore, immunoprecipitation assays show that VP1 and VP2 interact directly with each other, which indicates t hat the non-structural protein VP2 might act as a scaffold protein in virio n assembly. Recombinant baculovirus expressing VP1 and VP2 is, therefore, a potential production system for a subunit vaccine against CAV infection.