Role of gp-340 in HIV Infection and Transmission

描述(由申请人提供)：HIV-1进入靶细胞需要病毒包膜蛋白、CD4和趋化因子受体辅助受体之间的相互作用。病毒附着在细胞表面，这可能是感染的速度限制步骤，可以通过与各种分子的相互作用来调节，其中只有一些分子得到了很好的表征。GP-340是富含半胱氨酸的清道夫受体家族的成员。它被发现在肺泡巨噬细胞上，并结合表面活性蛋白来清除细菌，作为肺固有免疫系统的一部分。我们先前证明了GP-340以高亲和力结合HIV Env，并以其可溶性形式抑制HIV感染。某些针对GP-340的特异性抗体抑制了Env与GP-340的结合，用这种抗体处理表达细胞表面GP-340的单核细胞来源的巨噬细胞可减少急性HIV-1感染；提示可溶性和细胞表面GP-340对病毒感染具有相反的作用。GP-340也由上皮细胞表达，包括生殖道内的上皮细胞。我们观察到，表达GP-340的生殖器上皮细胞与HIV的脉冲作用导致了感染与反式感染的CD4+T细胞的有效结合和转移)。GP-340的结合增加了病毒的感染性和半衰期，并可被抗GP-340抗体和与GP-340结合的环境蛋白多肽所抑制。与其他HIV Env结合分子(DC-SIGN、Syndecan和甘露糖受体)不同的是，这些结合分子不介导融合而促进转染性感染，GP-340与Env之间的相互作用似乎涉及Env上的蛋白质。假说是通过GP-340与HIV Env之间的特异性相互作用，GP-340介导了反式HIV感染。我们将在四个具体目标上验证这一假说：1)鉴定用于与HIV Env结合的GP-340-TM的表位和氨基酸残基；2)分析与GP-340-TM结合的重要环境决定因素；3)研究GP-340-TM在HIV传播中的作用；以及4)研究HIV与表达内源性GP-340的生殖道上皮细胞结合后的传播。由于GP-340在HIV免疫发病机制(肺、脑、淋巴组织)和传播(生殖器上皮细胞)的许多区域都有表达，这些研究将对进一步了解HIV的传播和发病机制以及制定潜在的干扰HIV传播、感染和复制的途径具有重要意义。

DESCRIPTION (provided by applicant): The entry of HIV-1 into target cells requires interactions between the viral envelope (Env) protein, CD4, and a chemokine receptor coreceptor. Attachment of virus to the cell surface, which may be the rate limiting step to infection, can be mediated by interactions with a variety of molecules, only some of which have been well characterized. Gp-340 is a member of the scavenger receptor cysteine-rich family. It is found on alveolar macrophages and binds surfactant proteins to clear bacteria as part of the lung innate immune system. We previously demonstrated that gp-340 binds HIV Env with high affinity and, in its soluble form, inhibits HIV infection. Certain specific antibodies against gp-340 inhibit binding of Env to gp-340 and treatment of monocyte derived macrophages expressing cell surface gp-340 with such antibodies diminishes acute HIV-1 infection; suggesting that soluble and cell surface gp-340 have opposite effects on viral infection. Gp-340 is also expressed by epithelial cells including ones that line the genital tract. We observed that pulsing of genital epithelial cells expressing gp-340 with HIV results in efficient binding and transfer of infection to CD4+ T cells trans-infection). The binding by gp-340 increases the infectivity and half-life of virus and can be inhibited by anti-gp-340 antibodies and Env peptides shown to bind to gp-340. Unlike other HIV Env binding molecules that do not mediate fusion but promote trans-infection (DC-SIGN, syndecan, and mannose receptor) that bind Env carbohydrate, the interaction between gp-340 and Env appears to involve protein on Env. The hypothesis is that through specific interactions between gp-340 and HIV Env; gp-340 mediates trans- HIV infection. We will test this hypothesis in four specific aims: 1) the Identification of the epitope and amino acid residues of gp-340-Tm used in binding to HIV Env; 2) the analysis of Env determinants important in binding to gp-340-Tm; 3) the investigation of the role of gp-340-Tm in transmission of HIV; and 4) studies of the trafficking of HIV after binding to genital tract epithelial cells expressing endogenous gp-340. As gp-340 is expressed in many areas of HIV immunopathogenesis (lung, brain, lymphoid tissue) and transmission (genital epithelial cells), these studies will be important in further understanding HIV transmission and pathogenesis and for formulating potential avenues of interference in HIV transmission, infection, and replication.