SIV CORECEPTOR USAGE DETERMINES CD4+ T CELL DEPLETION

已经有充分的证据表明，进行性CD 4 + T细胞 艾滋病的消耗和发展与HIV-1密切相关 辅助受体从CCR 5转换到CXCR 4。 本研究的目的是 研究CD 4 + T细胞耗竭的基本机制 在艾滋病中的应用。 我们已经建立了一个 克隆的SIVmacEvT 3使用CXCR 4作为辅助受体并快速诱导 恒河猴中的CD 4 + T细胞耗竭。 相反，克隆 使用CCR 5的SIVmac 239不诱导CD 4 + T细胞耗竭。 的 EvT 3之间辅助受体使用和致病潜力的差异 和239由GP 120序列确定。 在这项研究中，我们 研究SIV CXCR 4使用的基本机制 有助于体内CD 4 + T细胞耗竭。 在这一年的第一年， 格兰特，我们建立了一个RT-PCR方法，定量检测 作为EvT 3和239的共受体起作用的CXCR 4、CCR 5的mRNA， 分别 我们发现，CXCR 4的表达在 恒河猴CD 4 + T细胞在静息和活化状态下均处于高水平 细胞，而CCR 5的表达仅限于活化的细胞。 这有力地表明，CXCR 4使用EvT 3将有助于 感染的CD 4 + T细胞，无论其活化状态。 我们 目前正在研究SIV辅助受体的使用是否与 CD 4 + T细胞中辅助受体的表达决定了 在体外和体外实验中， in vivo体内systems系统. 而EvT 3利用CXCR 4并诱导CD 4 + T细胞 消耗，目前尚不清楚CXCR 4的使用是否负责 EvT 3 gp 120中的CD 4 + T细胞耗竭或其它病毒因子 导致CD 4 + T细胞耗竭。 为了识别基因 CXCR 4使用的决定因素和EvT 3的致病潜力，我们 构建了各种重组体和位点特异性突变病毒。 我们的数据表明，EvT 3 CXCR 4在体外的使用主要是 由V3序列确定。 然而，初步数据显示， 除了CXCR 4的使用，一种未识别的病毒因子， EvT 3 gp 120是诱导CD 4 + T细胞耗竭所必需的。 vivo. 进一步的研究将是必要的，以了解基本的 CD 4 + T细胞耗竭的潜在机制和病毒的作用 病理事件中的辅助受体使用。 恒河猴模型 使用具有确定病毒序列的分子克隆SIV， 辅助受体的使用和致病潜力将大大有助于 更好地理解HIV-1辅助受体使用的意义 艾滋病患者的CD 4 + T细胞耗竭。 本研究还将 可能为开发新的 靶向阻断辅助受体的使用的抗病毒策略， HIV-1 Martin K，哈根S，Kodama T. SIV CXCR 4使用的遗传决定因素：V1和V3的作用 序列的 在第16届非人类灵长类动物模型年会上， 艾滋病（亚特兰大，佐治亚州，1998年10月7日至10日）（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).