| Porcine epidemic diarrhea (PED) caused by porcine epidemic diarrhea virus (PEDV) is an highly contagious enteric diaease of swine. Its prevailence has resulted in heavy economic losses in swine industry. Although the vaccine for PEDV had been commercialized, it still causing epidemic in China. Thus, developing an effective vaccine is an important research topic for prevention of PEDV infection.Spike (S) protein is one of the main structural protein of PEDV, and it can induce neutral antibody in vivo. Therefore it acts as candidated gene for developing novel vaccine of PEDV. In this study, PEDV S gene, PEDV S1 gene and porcine IL-18 gene were inserted into the eukaryotic expression vector, pVAX1, respectively, resulting in recombinant plasmids, pVAX1-PEDV S, pVAX1-PEDV S1 and pVAX1-pIL-18. The plasmids were transfected into BHK-21 cells and the results showed that the transient expression of the genes was recognized by respective antibodies.Experimental mice were divided into 7 groups, including pVAX1-PEDV S group, pVAX1-PEDV S1 group, pVAX1-pIL-18 group, pVAX1-PEDV S1 and pVAX1-pIL-18 group, TGEV-PEDV vaccine group, PBS control group and vector pVAX1 control group. Lymphocyte proliferative assay, enzyme linkered immunosorbent assay were used to analyze the immune response of different groups.The results showed that most of immune response of pVAX1-PEDV S group and pVAX1-PEDV S1 and pVAX1-pIL-18 group are higher than the pVAX1-PEDV S1 group, especially, the pVAX1-PEDV S1 and pVAX1-pIL-18 group. The details were as follows: the T lymphocyte proliferative function, the levels of special anti-PEDV antibody and IFN-γ, IL-4 expression in peripheral blood, Activity of CTL function in spleen and in peripheral blood were all higher than those of pVAX1-PEDV S1 group.The results indicated that pIL-18 can enhance the immune responses of DNA plasmid encoding the PEDV S in mice. This study provide useful data for rational design of novel DNA vaccine against PEDV. |
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