Baculovirus as a PRRSV and PCV2 bivalent vaccine vector: baculovirus virions displaying simultaneously GP5 glycoprotein of PRRSV and capsid protein of PCV2.

The GP5 glycoprotein of PRRSV is the main target for inducing neutralizing antibodies and protective immunity in the natural host. The capsid (Cap) protein is the major immunogenic protein and associated with the production of PCV2-specific neutralizing antibodies. In the present study, one genetic recombinant baculovirus BacSC-Dual-GP5-Cap was constructed. This virus displays simultaneously histidine-tagged GP5 and Cap proteins with the baculovirus glycoprotein gp64 TM and CTD on the virion surface as well as the surface of the virus-infected cells. After infection, the GP5 and Cap proteins were expressed and anchored simultaneously on the plasma membrane of Sf-9 cells, as revealed by Western blot and confocal microscopy. This report demonstrated first that both GP5 and Cap proteins were displayed successfully on the viral surface, revealed by immunogold electron microscopy. Vaccination of swine with recombinant baculovirus BacSC-Dual-GP5-Cap elicited significantly higher GP5 and Cap ELISA antibody titers in swine than the control groups. Virus neutralization test also showed that serum from the BacSC-Dual-GP5-Cap treated swine had significant levels of virus neutralization titers. Lymphocyte proliferation responses could be induced in swine immunized with BacSC-Dual-GP5-Cap than the control groups. These findings demonstrate that the BacSC-Dual-GP5-Cap bivalent subunit vaccine can be a potential vaccine against PRRSV and PCV2 infections.