肠道嗜性和神经嗜性SIV毒株Gp120序列变异特点的比对分析

目的研究SIVmac239在不同中国恒河猴体内由于免疫压力出现的病毒Env区的变异进化情况。比对分析可形成AIDS相关肠病和脑病的SIV病毒其Gp120序列的差异及特点。方法四株SIVmac239感染晚期发病恒河猴PBMC中分离的病毒及两株神经嗜性SIVmac251病毒,通过有限稀释分离培养病毒单克隆,提取病毒RNA后反转录,PCR扩增病毒gp120序列进行系统进化树分析。同时分析两组不同嗜性毒株Gp120氨基酸序列及糖基化位点的变化情况。结果 SIVmac239在四只恒河猴体内发生不同的变异进化。肠道嗜性毒株与神经嗜性毒株氨基酸序列的差异集中在V1和V4区,肠道嗜性毒株在V4区与一个糖基化位点的增加,而神经嗜性毒株的糖基化位点的变化都发生在保守区C1、C2和C3。结论 SIV肠道嗜性和神经嗜性的增强分别与包膜蛋白Gp120上V4区糖基化位点的增加和C1区的糖基化位点缺失相关,两种嗜性的差异并不表现在与嗜性形成有紧密联系的V3区上。

Analysis of Gp120 sequence differences between SIV strains with intestinal tropism and neurotropism

Objective To study the mutations of Env sequence of SIVmac239 after infection of Chinese rhesus monkeys, and compare the differences and characteristics of Gp120 sequences of enterotropic and neurotropic SIV strains. Methods Six strains of simian immunodeficiency virus were analyzed in this study: four separated from peripheral blood mononuclear cells of SIVmac239-infected monkeys and two neurotropic SIVmac251 strains. Isolated and cultured monoclonal virus was obtained by limiting dilution assay. Gp120 sequences were amplified after the RNA extraction and phylogenetic analysis was processed thereafter. So did the Gp120 amino acid sequence and N-glycosylation sites analysis of the enterotropic and neurotropic strains. Results SIVmac239 had different mutations in four rhesus monkeys. The diversity in amino acid sequences of the enterotropic and neurotropic strains concentrated in the V1 and V4 regions of Gp120. The enterotropic strains had an addition of glycosylation site in V4 but the glycosylation site changes of neurotropic strains were located in the conservative regions of C1, C2 and C3. Conclusions The addition of one glycosylation site in V4 region of GP120 and loss of one glycosylation site in C1 region are associated with enhanced enterotropism and neurotropism. The differences between the enterotropic and neurotropic strains are not dipicted in Gp120 V3 region which is closely related with the tropism of strains.