Study on immunological responses to eukaryotic expression vector containing PRRSV ORF5 and CpG motifs / 中国免疫学杂志

ABSTRACT

Objective:To enhance the immune efficiency of porcine reproductive and respiratory syndrome virus(PRRSV)DNA vaccine,the ORF5 genes were used as candidate genes to construct the recombinant plasmids CpG-pVAX1-ORF5 by pVAX1 as eukaryotic expression vector.The aim is to analyze the immune responses and the effects of CpG-ODN induced by GP5 recombinant plasmids of PRRSV.Methods:Piglets were immunized with recombinant DNA plasmids which expressed PRRSV GP5 for three inoculations.The PRRSV antibody in serum,the concentration of IL-2 and the lymphocyte proliferation test(MTT) in peripheral blood of vaccinated piglets were detected.The vaccinated pigs were challenged intranasally with PRRSV SD2.Results:GP5 DNA immunization with CpG resulted in the production of both PRRSV antibodies and cellular immune(a significant enhancement of a lymphoproliferative response ).The CpG-pVAX1-ORF5 was showed significantly better protection from the PRRSV challenge compared with the control plasmid.This immune response was characterized by a significantly decreased frequency of viraemia with decrease of 80% compared with the control group.There were little clinical symptoms and protection in some extent from lung damage.Conclusion:The results indicate that CpG-ODN could be used as immune adjuvant of PRRSV DNA vaccine.