HIV-1 CELLULAR IMMUNITY IN EXPOSED SERONEGATIVES

尽管反复发生性行为，但极少数人似乎对公开的HIV-1感染具有天然抵抗力。这些人被称为暴露的血清阴性者(ES)，他们代表了一个独特的群体，用来评估HIV-1复制被控制或中止的机制。1995年底，我们启动了一项针对健康的HIV-1血清阴性者的队列研究，每个人都报告与其感染HIV-1的伴侣进行了多次无保护的性接触。大约三分之一(13/36)的患者有可检测到的HIV-1特异性CTL，10%的患者有低水平的HIV-1特异性淋巴增殖(GoH)。我们在两个有细胞毒反应的ES的静息的CD4+T细胞群中发现了HIV-1转录本，其拷贝数非常低。这些发现表明，HIV特异性T细胞反应可能对显性感染产生获得性免疫防御。在这项提案中，我们打算在我们现有的48名ES及其24名受感染的伴侣中更严格地解决这一问题。在目标1中，我们将使用改进的抗原特异性CD8+T细胞检测技术(干扰素-γELISPOT和基于流式细胞术的分析)，纵向测定ES中HIV-1特异性CD8+T细胞的数量、表型和功能。我们假设ES中的CD8+T细胞反应将与HIV+性伴侣的精液中可检测到的HIV-1、最近暴露于HIV-1的频率和/或ES中静止的CD4+T细胞中潜伏病毒的检测相关。在目标2中，我们将检测ES中抗原反应性CD8+T细胞的HIV-1表位特异性、细胞杀伤和抗病毒活性。我们预测这些特异性将与自体潜伏病毒(如果发现)和来自感染伴侣的精液中的病毒发生交叉反应，并被定向到保守的HIV-1序列。在目标3中，我们将确定CD4+T辅助细胞(Th)对HIV-1抗原的特异性和表型，并评估对HIV-1 Gag蛋白的DTH反应。我们预测Th反应将定向到保守的辅助表位，表现为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暴露时驱动T细胞免疫的因素的新理解，并形成免疫谱系，以及这些反应可能如何与抑制HIV-1复制相关。这些见解可以应用于疫苗设计，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.