Optimizing HIV Env immuogens for T and B cell vaccine responses

描述（由申请人提供）： 鉴于疫苗试验的结果往往很差，在艾滋病毒疫苗领域出现了进行更多基础研究的趋势。由于HIV是一种免疫抑制病毒，其许多蛋白质会改变细胞功能，因此需要回答的一个重要基本问题是，在疫苗中使用HIV蛋白质对诱导的免疫反应有什么影响。我们证明了HIV Env作为一种呈现细胞相关三聚体的疫苗时，会抑制抗原特异性CD 4 + T细胞应答。我们证明了功能性三聚体Env异常地向CD 4 + T细胞发出信号并阻断它们的扩增，这可能导致中和抗体和CD 8 + T细胞应答的帮助不足。我们建议开发一种Env免疫原，当作为功能性细胞表面三聚体存在时，其不通过CD 4发出信号，从而保留CD 4辅助并保留能够诱导广泛交叉反应性中和抗体的表位。这种Env应该诱导更强的CD 8 + T细胞应答和中和抗体，因为中和表位的暴露更好或改变，这将被选择，并增加CD 4的帮助。我们还将研究保留介导进入和细胞-细胞融合能力的Env免疫原是否会呈现与中和最相关的功能结构域，并作为免疫原提供额外的优势。我们将使用一种新的小动物模型，这将使我们能够筛选免疫原的Env介导的免疫抑制活性和T和B细胞免疫应答。在三个具体目标中，我们将开发和测试Env免疫原。具体目标1：免疫原开发。 将开发不结合或不发信号通知CD 4并保留广泛中和表位（CD 4 bs、CD 4 i、MPER、碳水化合物（2G 12）、V2-V3）的Env。具体目的2：分析用于CD 4 + T细胞抑制和交叉反应性中和抗体表位表达的免疫原。将依次筛选免疫原的CD 4结合、CD 4信号传导和抑制CD 4 + T细胞增殖的能力。然后通过广泛交叉反应性中和单克隆抗体分析它们的结合，并且如果可能的话，通过广泛交叉反应性中和单克隆抗体分析它们的抑制。来自这些分析的数据将用于目标1中免疫原的进一步开发。目标2中的20种最佳免疫原将在目标3中进行研究。具体目标3：免疫人CD 4和CD 4/CCR 5转基因小鼠以分析有效CD 4 + T细胞辅助、交叉反应性中和抗体的产生和CD 8 + T细胞应答。我们将检验不抑制CD 4辅助的Env免疫原在抗原特异性细胞的频率和细胞的多功能性方面将具有更广泛的中和抗体应答和更好的CD 8应答的假设。本研究将分析去除HIV Env的免疫抑制活性对疫苗应答的影响，目的是开发更好的免疫原。人们认识到，需要一种艾滋病毒疫苗来控制传播是极其重要的。鉴于最近的临床试验失败，有必要进行侧重于疫苗开发基础生物学的研究。这笔赠款将用于研究和开发新的艾滋病毒包膜免疫原，用于疫苗开发。

DESCRIPTION (provided by applicant): A push to perform more basic studies has emerged in the HIV vaccine field given the often poor results in vaccine trails. As HIV is an immunosuppressive virus and many of its proteins alter cellular function, an important basic question that needs to be answered is what effect does using HIV proteins in a vaccine have on induced immune responses. We demonstrated that HIV Env, when delivered as a vaccine that presents cell-associated trimers, suppresses antigen-specific CD4+ T cell responses. We demonstrated that functional trimeric Env aberrantly signaled CD4+ T cells and blocked their expansion, which could lead to a deficiency in help for neutralizing antibody and CD8+ T cell responses. We propose to develop an Env immunogen that when presented as a functional cell surface trimer does not signal through CD4 thereby preserving CD4 help and retains epitopes capable of inducing broadly cross-reactive neutralizing antibodies. This Env should induce stronger CD8+ T cell responses and neutralizing antibodies because of better or altered exposure of neutralizing epitopes, which will be selected for, and increased CD4 help. We will also study whether Env immunogens that retain the ability to mediate entry and cell-cell fusion will present functional domains that are most relevant to neutralization and will provide additional advantages as immunogens. We will use a novel small animal model that will allow us to screen immunogens for both Env mediated immunosuppressive activities and T and B cell immune responses. In three specific aims, we will develop and test Env immunogens. Specific Aim 1: immunogen development. An Env that does not bind or signal CD4 and retains broad neutralization epitopes (CD4bs, CD4i, MPER, carbohydrate (2G12), V2-V3) will be developed. Specific Aim 2: analysis of immunogens for CD4+ T cell suppression and cross-reactive neutralizing antibody epitope expression. Immunogens will be sequentially screened for CD4 binding, CD4 signaling, and ability to suppress CD4+ T cell proliferation. They will then be analyzed for binding by, and, if possible, inhibition by broadly cross- reactive neutralizing monoclonal antibodies. Data from these analyses will be used in the further development of immunogens in Aim 1. The 20 best immunogens from Aim 2 will be studied in Aim 3. Specific Aim 3: immunization of human CD4 and CD4/CCR5 transgenic mice for analysis of effective CD4+ T cell help, development of cross-reactive neutralizing antibody, and CD8+ T cell responses. We will test the hypothesis that Env immunogens that do not suppress CD4 help will have broader neutralizing antibody responses and better CD8 responses with regard to both frequency of antigen-specific cells and multifunctionality of cells. This study will analyze the effect of removal of the immunosuppressive activity of HIV Env on vaccine responses with the goal of developing a better immunogen. The need for an HIV vaccine to control spread is recognized as extremely important. Given the failure of recent clinical trials, studies that focus on the basic biology of vaccine development are warranted. This grant will study and develop new HIV envelope immunogens for vaccine development.