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

描述（由申请人提供）： 事实证明，艾滋病毒疫苗的开发很困难；尽管最近的研究表明，对艾滋病毒有一定的保护作用是可能的。在过去的 16 年里，人们在感染 HIV 的（和未感染 HIV 的）人体中发现了能够在体外中和多种 HIV 分离株的抗体。施用这些广泛中和艾滋病毒抗体的混合物可降低受感染人类的​​艾滋病毒病毒载量，并减少艾滋病毒传播猴模型中的艾滋病毒传播。已经对这些 HIV 中和抗体进行了广泛的表征，并且已知其中一些抗体是多特异性的，可识别 HIV 糖蛋白上参与病毒-细胞融合 (gp41) 的隐藏区域，并且具有可能在 HIV 进入中发挥作用的细胞成分。迄今为止，这些抗体的主要限制是它们在用HIV gp41或用细胞成分免疫后不能可重复地或有效地产生。我发现一种常见的、明显非致病性的人类病毒（GB 病毒 C）在体外抑制 HIV 复制，并且同时感染 GBV-C 的 HIV 感染者比未感染 GBV-C 的人寿命更长。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分子的一部分。 E2 肽也被证明可以抑制融合。这些研究使我推测 E2 抗体可能会干扰 HIV 进入，并且本申请中描述的研究表明多种 GBV-C E2 抗体可以在体外中和 HIV 感染性。兔子的免疫接种， 携带重组 GBV-C E2 蛋白的小鼠和猴子会引发与 E2 蛋白反应的抗体，但也会与 HIV 颗粒上的细胞分子发生反应。该细胞分子不暴露在细胞表面。因此，我们假设 GBV-C E2 蛋白模仿了富含 HIV 颗粒的细胞分子的结构，并且与该抗原的结合降低了 HIV 的感染性。该提案的目的是：1) 生成工具，进一步表征这些抗体识别的 E2 和 HIV 颗粒分子，并确定产生 GBV-C E2 抗体的最佳免疫方法，2) 表征和鉴定参与 E2 抗体介导的中和的细胞分子。这些研究将深入了解生产艾滋病毒疫苗的新方法，并可能提供可用于开发艾滋病毒治疗的新分子。由于退伍军人事务部为美国最大的艾滋病毒感染者群体提供医疗服务，因此这项研究与退伍军人事务部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.