N-糖基化对乙型脑炎病毒prME和NS1基因免疫效果影响的研究

prME和NS1为乙型脑炎病毒两个主要的免疫保护蛋白,且均为N-糖蛋白。为研究N-糖基化对乙型脑炎病毒免疫保护的作用,本研究用PCR介导的定点突变方法,分别消除乙型脑炎病毒prME和NS1基因的不同N-糖基化位点,并构建了prME和NS1突变基因的真核表达质粒。将质粒免疫四周龄雌性小白鼠,经两次免疫后,采集血清检测体液免疫反应,最后对小鼠用强毒进行攻击,观察并记录免疫保护力。研究结果显示,与野生型prME基因免疫组相比,消除单个糖基化位点后prME基因诱导的ELISA抗体、中和抗体和免疫保护力均略有升高,而同时消除两个糖基化位点的则会降低。NS1基因消除单个糖基化位点后保护率高达到100%,但消除两个糖基化位点后则免疫保护率略有降低(75%)。通过本研究证明,N-糖基化在维系乙型脑炎病毒prME和NS1蛋白的免疫保护中具有重要的作用,单个糖基化的缺失可增强蛋白的免疫原性,而两个糖基都缺失后,则造成了免疫效率的降低。

Roles of N-glycosylation in immunity of prME and NS1 gene of JEV

PrME and NS1 gene were the two main immuneprotect proteins of Japanese encephalitis virus (JEV), and they were also N-linked glycosylation proteins. To clear the effect of N-glycosylation on JEV immunity, the N-glycosylation site of prME and NS1 gene were eliminated by site-directed mutant PCR, subtituting the N to Q. And the the mutant genes were subcloned into eukaryotic expression plasmid. Four-weeks female mice were immuned with the wildtype and mutant gene by twice. The antibodies against prME were detected by ELISA and the neutralization antibodies were tested by viral neutralizing assay. The immunoprotection were determined by attack with JEV virulent strain. Compare with the wild-type gene immuned-groups, one N-glycan eliminated prME gene could induce a little higher ELISA antibody, neutralization antibody and immunoprotection, but the immunity of gene with both N-glycan absence was decreased. The similar status were observed in the wildtype and mutant NS1 groups. Thus these results show that the N-linked glycosylation in the prME and NS1 gene were correlated with the immunity, one glycan absent would enhance the immunity but both two loss would impair it.