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推动。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的基本问题是，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，当HIV Env作为一种呈现细胞相关三聚体的疫苗递送时，可以抑制抗原特异性的CD4T细胞反应。我们证明了功能性三聚体Env异常地向CD4T细胞发出信号并阻止了它们的扩张，这可能导致中和抗体和CD8T细胞反应的帮助不足。我们建议开发一种环境免疫原，当作为功能细胞表面三聚体呈现时，不通过CD4发出信号，从而保留CD4帮助并保留能够诱导广泛交叉反应的中和抗体的表位。这种环境应该会诱导更强的CD8T细胞反应和中和抗体，因为更好的或改变了中和表位的暴露，这将被选为，并增加了CD4的帮助。我们还将研究保持介导进入和细胞-细胞融合能力的环境免疫原是否会提供与中和最相关的功能域，并将提供作为免疫原的额外优势。我们将使用一种新的小动物模型，该模型将允许我们筛选环境介导的免疫抑制活性以及T和B细胞免疫反应的免疫原。在三个具体目标中，我们将开发和测试环境免疫原。具体目标1：发展免疫基因。将开发一种不结合或不传递信号并保留广泛中和表位(CD4bs、CD4i、MPER、碳水化合物(2G12)、V2-V3)的Env。具体目的2：分析CD4T细胞抑制和交叉反应中和抗体表位表达的免疫原性。将对免疫原进行顺序筛选，以了解CD4结合、CD4信号和抑制CD4T细胞增殖的能力。然后将分析它们与广泛交叉反应的中和单抗的结合，如果可能的话，还会进行抑制。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中最好的20个免疫原将在目标3中进行研究。具体目标3：免疫人CD4和CD4/CCR5转基因小鼠以分析有效的CD4T细胞帮助、交叉反应中和抗体的产生和CD8T细胞反应。我们将测试这一假设，即不抑制CD4帮助的环境免疫原会在抗原特异性细胞的频率和细胞的多功能性方面具有更广泛的中和抗体反应和更好的CD8反应。本研究将分析去除HIV env免疫抑制活性对疫苗反应的影响，以期开发出更好的免疫原。人们认识到，需要艾滋病毒疫苗来控制传播是极其重要的。鉴于最近临床试验的失败，有必要对疫苗开发的基础生物学进行研究。这笔赠款将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.