SHIV_(SF162p3)病毒感染急性期复制水平与慢性期CD4^+ T细胞亚群分布及频度相关性分析

Experimental infection of SHIV_(SF162p3) in rhesus macaques:correlation analysis of the viral RNA levels in the acute phase and the distribution of CD4^+ T cell subsets in the chronic phase

目的研究B亚型强毒株SHIVSF162p3感染恒河猴后,在感染慢性期肠道组织、外周血及淋巴结中T淋巴细胞亚群的频率及其与急性期病毒复制强度的相关性。方法使用SHIVSF162p3通过静脉及黏膜途径感染12只中国恒河猴,real-time RT-PCR监测血浆病毒载量。感染慢性期取外周血、淋巴结以及通过内窥镜手术取十二指肠肠道黏膜组织,分离淋巴细胞,使用多色流式细胞术检测分析各组织中CD4+T细胞各亚群频率。结果与健康猴相比,SHIVSF162p3感染慢性期3种淋巴组织中CD4+T均有所下降且减少的主要部分是Tcm亚群,而CD4+Tcm下降在肠道组织中最为显著。与CD4+T细胞比较,慢性期CD4+Tcm的下降与急性期病毒载量峰值的相关性更高。从组织学来看,慢性期肠道组织CD4+Tcm与病毒载量峰值相关性最高,外周血次之;淋巴结的关联性不大。结论 B亚型强毒株SHIVSF162p3在急性感染期首先攻击肠道组织和外周血中CD4+Tcm细胞,造成靶细胞的严重损毁。病毒复制率越高损毁越严重,且持续至病毒感染慢性期,可能是这两种淋巴组织中CD4+T细胞下降的主要原因。而淋巴结中CD4+Tcm的下降则主要与外周血和淋巴结间的淋巴细胞循环相关。

Objective To evaluate the T cell subsets from intestine tissue,peripheral blood and lymph node in the chronic phase of experimentally-infected rhesus macaques and the correlation with the viral RNA level in the acute phase of the subtype B SHIVSF162p3 viral infection.Methods Twelve animals were challenged with SHIVSF162p3 intrarectally or intravenously.Whole blood was collected and the plasma virus was quantified by real-time RT-PCR.The distribution of CD4＋ T cell subsets in peripheral blood,inguinal lymph node and intestine tissue from chronically SHIVSF162p3 infected macaques was measured by multicolor flow cytometry.Results Comparing to the total number of total CD4＋ T cells,the proportion of CD4＋ Tcm（central memory） cells dropped significantly following SHIVSF162p3 infection with that in intestine dropped the most.The intestine-CD4＋ Tcm cells were negatively correlated with the peak of viral load detected in the acute phase of the viral infection.Conclusions The CD4＋ Tcm cells were massively and irreversibly depleted from the lymphoid tissues during the acute SHIVSF162p3 infection period,particularly in the intestine.The higher the peak viral load in the acute phase of infection,the fewer of CD4＋ Tcm cells were detected in the intestine during the chronic phase of infection.The decreased CD4＋ T cells in lymph nodes at chronic SHIVSF162p3 infection might be a result of reduced number of lymphocytes re-enter circulation rather than direct lymphocyte depletion.