表现神经症状的SIVmac251感染猴大脑基底节病毒gp120序列变异分析

目的 研究猴免疫缺陷病毒SIVmac251在中国恒河猴感染传代过程中产生的可能的神经侵袭性和神经嗜性及其分子机制.方法 从静脉感染SIVmac251-155p6N的8只实验猴中出现严重神经症状的1只猴中,监测病毒及免疫指标变化,观察临床症状、猴脑组织病变,单拷贝PCR扩增病毒gp120序列并分析变异及糖基化位点变化情况.结果 感染猴晚期出现明显艾滋病脑病症状,病理切片显示脑组织出现多核巨细胞及神经元变性、坏死.脑基底节分离出单一序列病毒,其氨基酸序列与血浆病毒及感染毒株SlVmac251-155p6序列差异主要位于Gp120的V1和V4区,并且在C1区66位出现一个糖基化位点缺失.结论 SIVmac251在猴体长期传代过程中表现出神经嗜性毒株的特征,对AIDS脑病研究具有重要意义.

Characterization of the SIVmac251 in a Chinese-origin rhesus macaque showing severe neurological symptoms and sequence variation of Gp120

Objective To investigate the possible neurotropism,neuroinvasion and their mechanism in a Chinese-origin rhesus macaque infected with SIVmac251 showing neurological symptoms.Methods Eight healthy laboratory rhesus macaques were infected with SIVmac251-155p6N by intravenous injection.Among them 3 monkeys showed neurological symptoms to a different degree,and one of these 3 animals（R21755） developed severe neurological symptoms.This monkey was sacrificed and the virus was isolated from the basal ganglia of the brain,the plasma viral load was quantified by real-time RT-PCR,and T cell subsets were determined by flow cytometry.The brain lesions were examined by histopathology using HE staining.The RNAs were extracted from SIVmac251-155p6N,plasma and basal ganglia,the gp120 genes were amplified with single genome amplification,and the changes of N-glycosylation site in gp120 regions were analyzed.Results The monkey R21755 presented AIDS encephalopathy-like symptoms after half a year post the viral infection.Pathological examination showed infiltration of macrophages and multinucleated giant cells in perivascular space,and degeneration and necrosis of neurons were observed in the brain tissue.The gp120 sequence analysis showed that the virus isolated from the brain was partly different from that of the other sequences of SIVmac251-155p6N and plasma virus of the monkey R21755.The variations were mainly in the V1/V4 regions and the loss of a N-glycosylation site in env C1.Conclusions It seems that the neuroinvasion and neurovirulence of SIVmac251 are significantly enhanced during the long-term adaption in vivo.The finding of this study provide a firm molecular basis for establishing a strain of SIVmac251 with neurotropism and neurovirulence.This would be very meaningful for investigating the role of SIV in neurologic disease and studies of AIDS neuropathy.