Construction And Immunogenicity Of Gene Engineering Vaccines Against PRRSV And PCV2

Porcine reproductive and respiratory syndrome virus(PRRSV) and porcine circovirus 2(PCV2) infections still remain today as the most significant health threat to swine and poses a challenge to current vaccination strategies.To obtain safe and effective recombinant vaccines against PRRSV and PCV2, ORF5 and ORF6 genes of PRRSV,ORF2 genes of PCV2 were cloned.Recombinant DNA vaccines and recombineant fowlpox virus(rFPV) coexpressing ORF5,ORF6 of PRRSV and ORF2 of PCV2 were constructed,and the immunogenicity of DNA vaccines and recombinant fowlpox viruses against PRRSV and PCV2 was evaluated.Mice immunized with the rFPV and DNA vaccines expressing ORF2 protein of PCV2 and GP5/GP6 of PRRSV developed a specific immune response against the PRRSV and PCV2 proteins.While the mechanisms responsible for protection against PRRSV and PCV2 infection remain unclear,our findings indicated that rFPV and DNA vaccine may be attractive vaccines for preventing diseases associated with PRRSV and PCV2 infection.The immunogenicity and protective efficiency of DNA vaccines were further evaluated in the piglets.Compared to PRRSV-PCV2 killed vaccine,detectable specific neutralizing antibody and higher lymphocyte proliferative responses could be developed in piglets immunized with DNA vaccines before virus challenge. Furthermore,more efficient protection against PRRSV-PCV2 challenge was obtained in piglets immunized with DNA vaccines,as showed by the balanced body-temperature fluctuation,milder lung lesions and lower proportion of virus load in tissues.