Characterization of cell GBV-C envelope glycoprotein interactions

描述(由申请人提供)： 与大多数为研究艾滋病毒复制而开发的体外系统不同，感染艾滋病毒的人与各种致病和非致病微生物共同感染。混合感染可能会影响任何一种感染的临床结果。例如，在HAART之前进行的所有研究中，艾滋病毒感染会加速丙型肝炎病毒(HCV)相关肝病的病程，而持续感染C型GB病毒(GBV-C)与艾滋病毒感染者的存活时间延长有关。微生物共感染相互作用改变病程的机制(S)提供了对艾滋病毒自然历史的洞察，并可能确定新的治疗目标或帮助制定预防策略。GBV-C是黄病毒科黄病毒属成员，是人类常见的传染病。该病毒在人的外周血单核细胞(PBMC)中复制，包括B和T淋巴细胞(CD4+和CD8+亚群)。PBMC与GBV-C和HIV共感染可抑制HIV复制，这部分是通过下调HIV协同受体和诱导可溶性抗病毒因子来实现的。GBV-C抑制CCR5和CXCR4嗜好的HIV分离株的复制，并抑制来自世界各地的多种HIV分支。此外，在接受IL-2治疗的人中，GBV-C感染似乎阻止了CD4的扩张，并与几种标志物(CD38、CCR5、CD25、CD69)表面表达的T细胞活性降低有关。添加包膜糖蛋白E2会复制其中的一些作用(CCR5调节，抑制HIV)，尽管它还没有得到彻底的研究。由于GBV-C E2蛋白在与GBV-C复制无关的情况下被加入细胞中，介导了HIV复制抑制，这可能是通过E2与其一个或多个细胞受体之间的相互作用来实现的。为了验证这一假设，我们计划描述GBV-CE2与其细胞受体(S)之间的相互作用，鉴定和验证候选的E2受体，确定E2上与细胞受体相互作用的结构域，并表征GBV-CE2如何调节细胞细胞因子、趋化因子和受体。初步数据已经确定了候选受体，最初的五个候选受体中有两个是淋巴细胞表面蛋白，它们在艾滋病毒复制和宿主免疫反应中都很重要。我们提出了四个目标，以进一步确定候选受体，验证这些受体与E2的相互作用，以及我们将评估E2和GBV-C颗粒与淋巴细胞(复制和非复制)相互作用对趋化因子受体表达、T细胞激活和抗HIV趋化因子诱导的影响。最后，我们将开始描述E2中负责结合和调节T细胞受体表达的区域。这些信息有可能促进基于细胞的、抗艾滋病毒和免疫调节治疗的开发。 公共卫生相关性： 退伍军人管理局的医疗保健系统是美国最大的艾滋病毒感染者提供者，虽然现在艾滋病毒可以通过抗逆转录病毒疗法(ART)进行管理，但抗逆转录病毒疗法成本高昂，副作用严重，而且很容易产生耐药性，特别是在不严格遵守治疗的患者中。GB病毒C是一种常见的人类病毒，似乎不会导致任何疾病，研究表明，它与艾滋病毒生长在相同的细胞中，从而抑制艾滋病毒的复制。这项申请建议研究一种GBV-C病毒蛋白(E2)如何修饰T细胞，使HIV不再生长，并将作为开发新的HIV治疗方法的基础。

DESCRIPTION (provided by applicant): Unlike most in vitro systems developed to study HIV replication, humans infected with HIV are co- infected with a variety of pathogenic and nonpathogenic microbes. Coinfections may influence the clinical outcome of either infection. For example, HIV infection accelerates the course of hepatitis C virus (HCV) related hepatic disease while persistent infection with GB virus type C (GBV-C) is associated with prolonged survival in HIV-infected individuals in all studies conducted prior to HAART. The mechanism(s) by which microbial coinfections interact to alter disease course provide insight into HIV natural history, and may identify novel therapeutic targets or assist in the development of prevention strategies. GBV-C is a member of the family Flaviviridae and GBV-C is a common infection of humans. The virus replicates in human peripheral blood mononuclear cells (PBMCs) including B and T lymphocytes (CD4+ and CD8+ subsets). Co-infection of PBMCs with GBV-C and HIV results in inhibition of HIV replication, and this is mediated in part by downregulation of HIV coreceptors and by induction of soluble antiviral factors. GBV-C inhibits the replication of both CCR5- and CXCR4-tropic HIV isolates, and inhibits diverse HIV clades from around the world. In addition, GBV-C infection appears to block CD4 expansion in people receiving IL-2 therapy and is associated with decreased T cell activation as measured by surface expression of several markers (CD38, CCR5, CD25, CD69). Addition of the envelope glycoprotein E2 reproduces some of these effects (CCR5 regulation, HIV inhibition) although it has not been thoroughly studied. Since GBV-C E2 protein, when added to cells independent of GBV-C replication mediates HIV replication inhibition, it is likely that this is mediated by interactions between E2 and its cellular receptor or receptors. To examine this hypothesis, we plan to characterize interactions between GBV-C E2 and it's cellular receptor(s), identify and validate candidate E2 receptors, determine the domains on E2 that interact with cellular receptors, and characterize how GBV-C E2 modulates cellular cytokines, chemokines and receptors. Preliminary data have identified candidate receptors, and two of the five initial candidates are lymphocyte surface proteins that are important in both HIV replication and host immune responses. We propose four aims to further identify candidate receptors, validate that these receptors interact with E2, and we will assess the effect of E2 and GBV-C particle interaction with lymphocytes (both replicating and not) on chemokine receptor expression, T cell activation, and induction of anti-HIV chemokines. Finally, we will begin characterization of the domain within E2 that is responsible for binding and modulating T cell receptor expression. This information has the potential to facilitate development of cellular-based, anti-HIV and immunomodulatory treatments. PUBLIC HEALTH RELEVANCE: The VA healthcare system is the largest provider for HIV-infection people in the United States, and although HIV can now be managed by antiretroviral therapy (ART), ART is expensive, has significant side effects, and resistance develops easily, particularly in patients who are not strictly adherent to therapy. GB virus C is a common human virus that does not appear to cause any disease, and studies show that it grows in the same cells as HIV resulting in inhibition of HIV replication. This application proposes to study how one of the GBV-C virus proteins (E2) modifies T cells so that HIV does not grow as well, and will serve as the basis for developing new approaches to HIV therapy.