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

描述（由申请人提供）： 尽管最近的研究表明，对艾滋病毒的一些保护是可能的，但艾滋病毒疫苗的开发已被证明是困难的。在过去的16年里，在HIV感染者（和未感染者）体内发现了抗体，这些抗体在体外中和了多种HIV分离株。给予这些广泛中和的HIV抗体的混合物降低了感染者中的HIV病毒载量，并减少了HIV传播的猴模型中的HIV传播。已经对这些HIV中和抗体进行了广泛的表征，并且已知这些抗体中的一些是多特异性的，识别HIV糖蛋白上参与病毒-细胞融合（gp 41）的隐藏区域，并且具有也可能在HIV进入中起作用的细胞成分。到目前为止，这些抗体的主要局限性是，它们不能在用HIV gp 41或细胞组分免疫后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，同时感染GBV-C的HIV感染者比没有感染GBV-C的人寿命更长。我们发现GBV-C感染淋巴细胞，包括CD 4细胞，其他人发现GBV-C包膜糖蛋白E2抑制HIV融合，就像gp 41分子的一部分。E2肽也显示出抑制融合。这些研究使我假设E2抗体可能干扰HIV进入，本申请中描述的研究表明，多种GBV-C E2抗体在体外中和HIV感染性。兔子的免疫， 小鼠和猴子用重组GBV-CE 2蛋白激发抗体，该抗体与E2蛋白反应，但也与HIV颗粒上的基于细胞的分子反应。这种细胞分子不暴露在细胞表面。因此，我们假设GBV-CE 2蛋白模拟了HIV颗粒上富集的细胞分子的结构，并且与这种抗原结合降低了HIV感染性。本提案的目的是：1）生成允许进一步表征这些抗体识别的E2和HIV颗粒分子的工具，并确定产生GBV-C E2抗体的最佳免疫方法，以及2）表征和鉴定参与E2抗体介导的中和的细胞分子。这些研究将为产生HIV疫苗的新方法提供深入了解，并可能提供可用于开发HIV治疗的新分子。由于VA为美国最大的HIV感染者群体提供医疗护理，因此这项研究与VA的研究使命高度相关。

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.