Enhanced humoral and cellular immune responses to PRRS virus GP5 glycoprotein by DNA prime-adenovirus boost vaccination in mice.

In order to investigate the induction of humoral and cellular immune responses against porcine reproductive and respiratory syndrome virus (PRRSV), BALB/c mice were immunized in a pcDNA3-GP5 prime-rAd-GP5 boost regimen. After humoral and cellular immune response detection, levels of PRRSV-specific antibodies, neutralizing antibodies, lymphocyte proliferation response, and cytotoxic T-lymphocyte response were significantly increased as compared to controls. The humoral immune response was induced more effectively by the DNA priming and recombinant adenovirus boosting regimen. Significant difference was observed between heterogeneous and homologous vaccination. Induction of anti-GP5 antibody response was higher in all heterogeneous combinations than those of the homologous combinations. In the induction of lymphocyte proliferation response and CTL response, the homologous combination of pcDNA3-GP5/pcDNA3-GP5/pcDNA3-GP5was significantly stronger than that of rAd-GP5/rAd-GP5/rAd-GP5, but was relatively weaker than the heterogeneous combination of pcDNA3-GP5/pcDNA3-GP5/rAd-GP5 and pcDNA3-GP5/rAd-GP5/rAd-GP5. This heterogeneous combination was a most efficient immunization regimen in induction of PRRSV-specific cellular immune response just as the antibody response. These results suggested that DNA immunization followed by recombinant adenovirus boosting could be used as a potential PRRSV vaccine.