GBV-C E2 protein mimics a cellular antigen involved in HIV-1 entry

描述(由申请人提供)： 艾滋病毒疫苗的开发被证明是困难的；尽管最近的研究表明，对艾滋病毒有一定的保护是可能的。在过去的16年里，在感染艾滋病毒的人(和未感染艾滋病毒的人)中发现了抗体，这些抗体在体外中和了不同的艾滋病毒分离株。服用这些广泛中和的艾滋病毒抗体的鸡尾酒可以减少感染者中的艾滋病毒病毒载量，并减少艾滋病毒传播的猴子模型中的艾滋病毒传播。已经对这些艾滋病毒中和抗体进行了广泛的表征，众所周知，其中一些抗体是多特异性的，识别参与病毒-细胞融合的艾滋病毒糖蛋白上的一个隐藏区域(Gp41)，以及可能在艾滋病毒侵入过程中发挥作用的细胞成分。到目前为止，这些抗体的主要局限性是，在用艾滋病毒gp41或细胞成分免疫后，它们不能重复或有效地产生。我发现一种常见的、明显非致病的人类病毒(GB病毒C)在体外抑制艾滋病毒的复制，同时感染GBV-C的HIV感染者比没有GBV-C的人活得更长。我们发现GBV-C感染淋巴细胞，包括CD4细胞，其他人发现GBV-C包膜糖蛋白E2抑制HIV融合，很像gp41分子的一段。研究表明，E2多肽也能抑制融合。这些研究让我假设，E2的抗体可能会干扰HIV的进入，本申请中描述的研究表明，各种GBV-C E2抗体在体外可以中和HIV的传染性。对兔子的免疫， 小鼠、猴子和重组GBV-C E2蛋白诱导的抗体与E2蛋白反应，但也与HIV颗粒上的细胞分子反应。这种细胞分子不会暴露在细胞表面。因此，我们假设GBV-C E2蛋白模拟了富含HIV颗粒的细胞分子结构，并且与这种抗体结合降低了HIV的传染性。这项建议的目的是：1)开发工具，进一步鉴定这些抗体识别的E2和HIV颗粒分子，并确定提高GBV-C E2抗体的最佳免疫方法；2)表征和鉴定参与E2抗体介导的中和作用的细胞分子。这些研究将提供对产生艾滋病毒疫苗的新方法的洞察，并可能提供可用于开发艾滋病毒治疗的新分子。由于退伍军人管理局为美国最大的艾滋病毒感染者提供医疗服务，这项研究与退伍军人管理局的研究任务高度相关。

DESCRIPTION (provided by applicant): Development of an HIV vaccine has proven difficult; although recent studies suggest that some protection against HIV is possible. Over the past 16 years, antibodies have been found in HIV-infected (and HIV-uninfected) humans that neutralize diverse isolates of HIV in vitro. Administration of a cocktail of these broadly neutralizing HIV antibodies decreased HIV viral load in infected humans and to reduced HIV transmission in a monkey model of HIV transmission. Extensive characterization of these HIV neutralizing antibodies has been conducted, and it is known that the some of these antibodies are polyspecific, recognizing a hidden region on the HIV glycoprotein that is involved in virus-cell fusion (gp41), and with cellular constituents that may also play a role in HIV entry. Thus far, the major limitation of thee antibodies is that they have not been able to be reproducibly or potently produced following immunization with either the HIV gp41 or with cellular components. I found that a common, apparently nonpathogenic human virus (GB virus C) inhibits HIV replication in vitro, and that HIV infected people who are coinfected with GBV-C live longer than those who do not have GBV-C. We found that GBV-C infects lymphocytes, including CD4 cells, and others found that the GBV-C envelope glycoprotein E2 inhibits HIV fusion, much like a piece of the gp41 molecule. E2 peptides have been shown to inhibit fusion as well. These studies led me to hypothesize that antibodies to E2 might interfere with HIV entry, and studies described in this application show that a variety of GBV-C E2 antibodies neutralize HIV infectivity in vitro. Immunization of rabbits, mice, and monkeys with recombinant GBV-C E2 protein elicits antibodies that react with E2 protein, but also react with a cellular-based molecule on HIV particles. This cellular molecule is not exposed on the surface of cells. Thus we hypothesize that GBV-C E2 protein mimics the structure of a cellular molecule that is enriched on HIV particles, and that binding to this antige decreases HIV infectivity. The purpose of this proposal is to: 1) generate tools that will allow further characterization of the E2 and HIV particle molecule recognized by these antibodies, and determine the optimal immunization method for raising antibodies to GBV-C E2, and 2) characterize and identify the cellular molecule involved in E2 antibody mediated neutralization. These studies will provide insight into a new method of generating a HIV vaccine, and may provide new molecules that can be targeted for the development of HIV treatments. Since the VA provides medical care to the largest single population of HIV-infected people in the United States, this research is highly relevant to the VA research mission.