Baculovirus surface display of E2 envelope glycoprotein of classical swine fever virus and immunogenicity of the displayed proteins in a mouse model

Classical swine fever virus (CSFV) causes significant losses in pig industry in many countries. The E2 glycoprotein of CSFV is the main target for inducing neutralizing antibodies and protective immunity in the natural host. In this study, one recombinant baculoviruses BacSC-E2 expressing histidine-tagged E2 with the CTD and TM derived from baculovirus envelope protein gp64 was constructed and evaluated its vaccine efficacy in mice model. After infection, E2 was expressed and anchored on the plasma membrane of Sf-9 cells, as revealed by confocal microscopy. Immunogold electron microscopy demonstrated that the BacSC-E2 was displayed E2 glycoprotein on the viral surface. Animal vaccine tests showed that BacSC-E2 elicited significantly higher E2 antibody titers in the treated mouse models than the control group. Virus neutralization test showed that serum from the BacSC-E2 treated models had significant levels of virus neutralization activities. This demonstrates that the BacSC-E2 vaccine can be a potential vaccine against CSFV infections. This is the first report demonstrating that the potential of E2-pseudotyped baculovirus as a classical swine fever virus vaccine.