HIV-1 CELLULAR IMMUNITY IN EXPOSED SERONEGATIVES

尽管反复接触HIV-1，但很少有个体表现出对明显HIV-1感染的天然抗性。这些人被称为暴露血清阴性（ES），代表了一个独特的群体，可以评估控制或终止HIV-1复制的机制。1995年底，我们对健康的艾滋病毒-1血清检测呈阴性的人开展了一项队列研究，每个人都报告与感染艾滋病毒-1的伴侣多次发生无保护的性接触。大约三分之一（13/36）有可检测到的hiv -1特异性CTL， 10%有低水平的hiv -1特异性淋巴细胞增殖（Goh）。我们发现HIV-1转录物拷贝数非常低，在两个ES的静止CD4+ T细胞群中有细胞毒性反应。这些发现表明hiv特异性T细胞反应可能对显性感染施加获得性免疫防御。在这项建议中，我们打算在我们现有的48名ES和24名受感染的伙伴中更严格地处理这一问题。在Aim 1中，我们将使用改进的技术来检测抗原特异性CD8+ T细胞（ifn - γ ELISpot和流式细胞术为基础的分析），纵向确定ES中hiv -1特异性CD8+ T细胞的数量、表型和功能。我们假设ES患者的CD8+ T细胞反应与HIV阳性性伴侣精液中可检测到的HIV-1、近期暴露于HIV-1的频率和/或ES患者静息CD4+ T细胞中潜伏病毒的检测相关。在目标2中，我们将检查ES中抗原反应性CD8+ T细胞的HIV-1表位特异性、细胞溶解和抗病毒活性。我们预测特异性将与自体潜伏病毒（如果发现）和感染伴侣精液中的病毒发生交叉反应，并指向保守的HIV-1序列。在Aim 3中，我们将确定CD4+ T辅助（Th）对HIV-1抗原反应的特异性和表型，并评估DTH对HIV-1 Gag蛋白的反应。我们预测Th反应将指向保守的辅助表位，表现出Th1表型，并与gag特异性DTH反应相关。我们的研究将提供对HIV-1暴露驱动T细胞免疫和形成免疫库的因素的新理解，以及这些反应如何与减少HIV-1复制相关。这些见解可应用于疫苗设计，评估艾滋病毒候选疫苗对免疫反应的诱导，并指导与疫苗效力相关的终点的定义。

Rare individuals appear naturally resistant to overt HIV-1 infection despite repeated sexual exposures. These persons, termed exposed seronegatives (ES) represent a unique population to evaluate mechanisms by which HIV-1 replication is either controlled or aborted. In late 1995 we initiated a cohort study of healthy HIV-1 seronegative persons, each reporting repeated unprotected sexual contact with their HIV-1-infected partner. Approximately one-third (13/36) have detectable HIV-1-specific CTL and 10 percent have low levels of HIV-1-specific lymphoproliferation (Goh). We discovered HIV-1 transcripts in very low copy numbers in the resting CD4+ T cell population of two ES with cytotoxic responses. These findings suggest that the HIV-specific T cell responses may exert an acquired immune defense against overt infection. In this proposal we intend to address this issue more rigorously in our existing cohort of 48 ES and 24 of their infected partners. In Aim 1, we will determine longitudinally the quantity, phenotype and function of HIV-1-specific CD8+ T cells in ES using improved technology to detect antigen-specific CD8+ T cells IFN-gamma ELISpot and flow cytometric-based analyses). We hypothesize that the CD8+ T cell responses in ES will correlate with detectable HIV-1 in semen of the HIV+ sexual partner, the frequency of recent exposures to HIV-1, and/or the detection of latent virus in resting CD4+ T cells in ES. In Aim 2, we will examine the HIV-1 epitope specificities, cytolytic and anti-viral activities of the antigen reactive CD8+ T cells in ES. We predict the specificities will cross react with the autologous latent virus (if found) and virus in semen from the infected partner, and be directed to conserved HIV-1 sequences. In Aim 3, we will determine the specificity and phenotype of CD4+ T helper (Th) responses to HIV-1 antigens and assess DTH responses to an HIV-1 Gag protein. We predict that Th responses will be directed to conserved helper epitopes, exhibit the Th1 phenotype, and be associated with Gag-specific DTH responses. Our studies will provide new understanding of the factors that drive T cell immunity with HIV-1 exposure and shape the immune repertoire, and how these responses may be relevant to curtailing HIV-1 replication. These insights can be applied to vaccine design, to assess induction of immune responses by HIV vaccine candidates and to guide the definition of endpoints related to vaccine efficacy.