表达猪流行性腹泻病毒截短S1的重组猪痘病毒的构建及免疫评价

Porcine Epidemic Diarrhea virus (PEDV) causes significant economic losses to the swine industry. Commercial vaccines are available, but are not effective on farms against the outbreak in China of a novel PEDV strain, SQ2014. A recombinant swinepox virus vaccine (rSPV-Sa) expressing the truncated S protein from PEDV strain SQ2014 was constructed, and its immunogenicity and efficacy were tested and characterized. Vaccination robustly increased the IgG titer specific for PEDV (SQ2014) and induced neutralizing antibodies with a mean titer of 1:24 at 42 days post-inoculation. The rSPV-Sa group serum IgA levels were significantly higher than those killed vaccine groups. The efficacy of the rSPV-Sa vaccine was tested in passive transfer models using homologous (SQ2014) and heterologous (CV777) challenges. In the homologous challenge, rSPV-Sa provided complete protection. None of the challenged animals showed clinical symptoms of PEDV infection and there was no mortality. The rSPV-Sa vaccine did not show protective efficacy in the heterologous challenge (100% mortality in challenged animals). Differences in the amino acid sequences of the two viruses were identified in the neutralizing epitopes and might have contributed to the divergent clinical results. The data suggest that rSPV-Sa is a potential vaccine against new strain of PEDV infection.