SIV CORECEPTOR USAGE DETERMINES CD4+ T CELL DEPLETION

已经有很好的文献记载，进行性的CD4+T细胞 艾滋病的耗尽和发展与HIV-1密切相关 辅受体从CCR5切换到CXCR4。这项研究的目的是 探讨CD4+T细胞耗竭的基本机制 在艾滋病中使用SIV动物模型系统。我们已经构建了一个 克隆的以CXCR4为辅助受体并快速诱导的SIVmacEvT3 恒河猴体内CD4+T细胞的耗竭。相比之下，克隆的 使用CCR5的SIVmac239不会导致CD4+T细胞耗尽。这个 EvT3共受体用法和致病潜能的差异 和239由gp120序列决定。在这项研究中，我们是 探讨SIV CXCR4使用的基本机制 在体内导致了CD4+T细胞的耗尽。在今年的第一年 格兰特，我们建立了一种RT-PCR方法，可以定量检测 作为EvT3和239的辅助受体的CXCR4、CCR5的mRNA， 分别进行了分析。我们发现CXCR4在 恒河猴在静息和激活状态下的高水平CD4+T细胞 CCR5的表达仅限于激活的细胞。 这有力地表明，EvT3的CXCR4的使用将促进 感染CD4+T细胞，而不考虑其激活状态。我们 目前正在调查SIV共受体的用法是否耦合 辅受体在CD4+T细胞中的表达决定了 体外和体外培养的CD4+T细胞对SIV感染的敏感性 活体系统。而EvT3使用CXCR4并诱导CD4+T细胞 耗尽，尚不清楚CXCR4的使用是否导致 EvT3gp120中的CD_4~+T细胞耗竭或其他病毒因子(S) 导致了CD4+T细胞的耗尽。以确定基因 CXCR4的用途和EvT3型致病潜能的决定因素(S) 构建了多种重组体和定点突变病毒。 我们的数据表明，EvT3CXCR4在体外的使用主要是 由V3序列决定。然而，初步数据显示， 除了CXCR4的使用，还有一个不明的病毒因素 EvT3 gp120是诱导CD_4~+T细胞耗竭所必需的 活着。有必要进行进一步的研究，以了解 CD4+T细胞耗竭的机制及病毒的作用 辅助受体在病理事件中的使用。恒河猴模型 使用具有定义的病毒序列的分子克隆的SIV， 辅受体的使用和致病潜力将极大地促进 更好地理解HIV-1共受体用法的意义 用于艾滋病患者的CD4+T细胞耗竭。这项研究还将 有可能为小说的发展提供有用的信息 以阻断辅受体的使用为目标的抗病毒策略 HIV-1。资助NIH AI42508出版物Martin K，Hgen S，KoDama T. SIV CXCR4使用的遗传决定因素V1和V3的作用 序列。在第16届非人灵长类动物模型年度研讨会上 艾滋病(1998年10月7日至10日在佐治亚州亚特兰大举行)(摘要3)。

It has been well documented that the progressive CD4+ T cell depletion and development of AIDS are closely associated to an HIV-1 coreceptor switch from CCR5 to CXCR4. The objective of this study is to investigate the basic mechanisms underlying CD4+ T cell depletion in AIDS using an SIV animal model system. We have constructed a cloned SIVmacEvT3 that uses CXCR4 as a coreceptor and rapidly induces CD4+ T cell depletion in rhesus macaques. In contrast, a cloned SIVmac239 that uses CCR5 does not induce CD4+ T cell depletion. The differences of coreceptor usage and pathogenic potential between EvT3 and 239 are determined by the gp120 sequences. In this study, we are investigating the basic mechanisms by which SIV CXCR4 usage contributes to CD4+ T cell depletion in vivo. In Year 1 of this grant, we established an RT-PCR method that quantitatively detects mRNA of CXCR4, CCR5 that function as coreceptors for EvT3 and 239, respectively. We found that CXCR4 was consistently expressed in rhesus CD4+ T cells at high levels in both resting and activated cells, whereas CCR5 expression was restricted to activated cells. This strongly suggests that the CXCR4 usage of EvT3 would facilitate infection of CD4+ T cells regardless of their activation status. We are currently investigating whether the SIV coreceptor usages coupled with the expression of coreceptors in CD4+ T cells determines the susceptibility of CD4+ T cells to SIV infection in both in vitro and in vivo systems. While EvT3 uses CXCR4 and induces CD4+ T cell depletion, it is not clear whether the CXCR4 usage is responsible for the CD4+ T cell depletion or other viral factor(s) in EvT3 gp120 contributes to the CD4+ T cell depletion. To identify genetic determinant(s) for CXCR4 use and pathogenic poten tial of EvT3, we constructed various recombinants and site-specific mutant viruses. Our data demonstrated that the EvT3 CXCR4 usage in vitro was primarily determined by the V3 sequences. However, preliminary data suggested that, in addition to the CXCR4 usage, an unidentified viral factor in EvT3 gp120 was required for the induction of CD4+ T cell depletion in vivo. Further studies will be warranted to understand the basic mechanisms underlying CD4+ T cell depletion and the role of viral coreceptor usage in the pathological event. The rhesus macaque model using the molecularly cloned SIV with a defined viral sequence, coreceptor usage and pathogenic potential will greatly contribute to better understanding of the significance of HIV-1 coreceptor usages for CD4+ T cell depletion in AIDS patients. This study will also potentially provide useful information for development of novel antiviral strategies that target to block the use of coreceptors by HIV-1. FUNDING NIH AI42508 PUBLICATIONS Martin K, Hagen S, Kodama T. Genetic determinants of SIV CXCR4 usage the role of V1 and V3 sequences. In 16th Annual Symposium on Nonhuman Primate Models for AIDS (held in Atlanta, GA, October 7-10, 1998) (abstract 3).