Mechanisms Underlying Persistent Lentivirus Replication in Follicular T Cells

描述（由申请方提供）：在慢性HIV-1和SIV感染中，病毒复制集中在淋巴组织中的滤泡CD 4 + T细胞中，其被有效感染的可能性是滤泡外CD 4 + T细胞的30 - 40倍。慢病毒优先被滤泡性CD 4 + T细胞复制的原因以及病毒特异性细胞毒性T淋巴细胞（CTL）不能抑制这些细胞中的复制的原因尚不清楚。急性SIV感染时病毒复制不集中在B细胞滤泡中，提示滤泡中病毒浓度可能与获得性免疫有关。T滤泡辅助细胞（TFH）是迁移到B细胞滤泡中的抗原特异性细胞的特化亚群，在那里它们与B细胞和滤泡树突状细胞（FDC）相互作用以促进B细胞成熟和抗体产生。我们假设病毒复制集中在慢性HIV-1和SIV感染的TFH内，这是由于1）TFH对生产性慢病毒感染的内在易感性增加，2）它们位于FDC上抗体-病毒体复合物附近的生发中心（GC），以及3）滤泡CTL的数量和功能缺陷。这些假设将通过一系列体外和体内实验进行测试，使用人类和恒河猴的淋巴组织。在目的1中，我们将通过用GFP报告病毒进行体外实验感染来确定人和猕猴TFH是否本质上比其他CD 4 + T细胞更容易受到生产性慢病毒感染。在目标2中，我们将通过原位组织分析以及测量在慢性和急性慢病毒感染中的分选的亚群中的病毒RNA，来确定在体内生产性感染的T细胞的分布和表型。 细胞在目标3中，我们将研究以下假设： 滤泡CTL有助于HIV-1在B细胞滤泡内的增殖，使用滤泡CTL功能的体外测定中的原位研究和恒河猴体内的CD 8耗竭。在所有目标的背景下，我们将评估T滤泡调节细胞（TFR）对HIV-1复制和CTL功能的影响。总的来说，这些研究将提供大量关于促进HIV-1在B细胞滤泡中复制的细胞和滤泡环境中可能促进或损害慢病毒复制的因子的新信息。更好地理解滤泡CD 4 + T细胞对慢病毒的宽容机制对于开发HIV-1的保护性疫苗或功能性治疗至关重要。

DESCRIPTION (provided by applicant): In both chronic HIV-1 and SIV infection, virus replication is concentrated in lymphoid tissues in follicular CD4+ T cells, which are 30 to 40 times more likely to be productively infected than extrafollicular CD4+ T cells. Reasons why lentiviruses are preferentially replicated by follicular CD4+ T cells and why virus-specific cytotoxic T lymphocytes (CTL) cannot suppress replication in these cells are not understood. Virus replication is not concentrated in B cell follicles in acute SIV infection, suggesting that te follicular concentration of virus may be related to adaptive immunity. T follicular helper cells (TFH) are a specialized subset of antigen-specific cells that migrate into B cell follicles where they interact with B cells and follicular dendritic cells (FDC) to promote B cell maturation and antibody production. We hypothesize that virus replication is concentrated within TFH in chronic HIV-1 and SIV infection due to 1) increased intrinsic susceptibility of TFH to productive lentiviru infection, 2) their location in germinal centers (GC) adjacent to antibody-virion complexes on FDC, and 3) numerical and functional deficiencies of follicular CTL. These hypotheses will be tested through a series of experiments both in vitro and in vivo using lymphoid tissues from humans and rhesus macaques. In Aim 1, we will establish whether human and macaque TFH are intrinsically more susceptible to productive lentivirus infection than other CD4+ T cells through in vitro experimental infections with GFP reporter viruses. In aim 2, we will determine the distribution and phenotype of productively infected T cells in vivo in both chronic and acute lentivirus infection by in situ tissue analyses as well as measuring viral RNA in sorted subsets of cells. In Aim 3 we will investigate the hypothesis that numerical and/or functional deficiencies in follicular CTL contribute to the propagation of HIV-1 within B cell follicles using in situ studies in vitro assays of follicular CTL function, and CD8 depletion of rhesus macaques in vivo. In the context of all aims, we will evaluate the impact of T follicular regulatory cells (TFR), on HIV-1 replication and CTL function. Collectively, these studies will provide a wealth of new information on the cells that foster HIV-1 replication in B cell follicles and factors in the follicular milieuthat may promote or impair lentivirus replication. A better understanding of the mechanisms that underlie permissiveness of follicular CD4+ T cells to lentiviruses is vital to development of a protective vaccine or a functional cure for HIV-1.