Epitope-Focused HIV-1 Envelope Vaccine for HIV-1/AIDS

描述(由申请人提供)：该项目的总体目标是探索和推进结构受限形式的HIV-1包膜(Env)蛋白，用于开发HIV-1疫苗。病毒包膜蛋白gp120的配方可以对人类免疫系统进行编程，以识别和阻断HIV-1包膜蛋白，这一直是艾滋病疫苗开发的主要目标。然而，gp120被发现能够逃避免疫监视，这主要是由于它的构象灵活性。识别提高结构稳定性的方法，特别是通过保守的表位聚焦，被视为提高包膜疫苗诱导中和免疫反应能力的一个重要目标。最近，我们开发了一系列的分子，称为“变构双部位拮抗剂”，它可以与病毒gp120强烈结合，从而将gp120包裹在一个功能被抑制的三维结构中，但带有一个可访问的CD4Phe 43结合口袋。我们假设变构双位点拮抗剂可以诱导HIV-1被膜蛋白免疫原性的改变，并且这种改变可以潜在地导致针对保守的受体结合位点的中和免疫反应增强，包括针对CD4的中和反应。我们将在这个PIA项目的R21阶段测试这一假设，主要有两个目标。(R21-Aim1)利用重组蛋白质工程和多肽合成，我们的目标是生产HIV-1Env免疫原，其中HNG-156类变构双部位拮抗剂与HIV-1gp120的重组三聚体和单体非共价或共价结合。(R21-AIM2)利用小动物模型，我们的目的是验证这样一种假设，即变构gp120抑制剂与重组三聚体和单体HIV-1 gp120的复合体和共价融合免疫将产生增强的抗HIVgp120特异性抗体和T细胞表位的广度、大小和B细胞的中和能力。R21项目的关键里程碑将是展示HIV-1Env gp120的变构双部位拮抗剂促进的增强的血清中和活性。 这一里程碑的实现将导致R33开发阶段，其中包括鉴定具有优化组成的HIV-1 Env非共价和共价结合到变构抑制剂(R33-Aim1)的高级免疫原；使用具有粘膜挑战的非人灵长类动物模型测试免疫原(R33-AIM2)；以及生产潜在的中和单抗，由Env-变构抑制免疫原激发，其特征将是Env结合表位和中和广度(R33-Aim3)。 总体而言，该项目将通过构象约束使用表位聚焦来了解变构配体如何以免疫原性产生的方式控制HIV-1环境蛋白的构象，识别HIV-1环境中用于保护性免疫的中和位点，开发用于非人类灵长类动物有效性/毒性评估的环境蛋白构建体，并将免疫原制剂推进到灵长类动物，并最终用于人体试验。 公共卫生相关性：该项目寻求测试新发现的HIV-1病毒外壳蛋白形式，作为设计可用于对人类提供免疫保护的艾滋病疫苗的工具。

DESCRIPTION (provided by applicant): The overall goal of this project is to explore and advance structurally constrained forms of HIV-1 envelope (Env) protein for development of an HIV-1 vaccine. Formulations of viral envelope protein gp120 that could program the human immune system to recognize and block the HIV-1 envelope protein have been a major goal of AIDS vaccine development. However, gp120 has been found to be able to evade immune surveillance, due significantly to its conformational flexibility. Identifying approaches to induce increased structural stability, in particular by conserved epitope focusing, is seen as an important goal to improve the ability of envelope vaccines to elicit neutralizing immune responses. Recently, we have developed a set of molecules, called "allosteric dual site antagonists", that can bind strongly to the viral gp120 in such a way as to entrap gp120 in a three dimensional structure that is functionally suppressed but with an accessible CD4 Phe 43 binding pocket. We hypothesize that allosteric dual site antagonists can induce an altered immunogenic landscape in HIV-1 envelope protein, and that such an altered landscape can potentially lead to an enhanced neutralizing immune response against conserved receptor binding sites, including that for CD4. We will test this hypothesis in the R21 phase of this PIA project with 2 major aims. (R21-Aim1) Using recombinant protein engineering and peptide synthesis, we aim to produce HIV-1 Env immunogens in which allosteric dual site antagonists of the HNG-156 class are bound either noncovalently or covalently with recombinant trimeric and monomeric forms of HIV-1 gp120. (R21-Aim2) Using small animal models, we aim to test the hypothesis that vaccination of complexes and covalent fusions of allosteric gp120 inhibitors with recombinant trimeric and monomeric forms of HIV-1 gp120 will elicit enhanced anti-HIVgp120 specific antibody and T cell epitope breadth, magnitude and the neutralization capacity of B cells. The key milestone of the R21 project will be to demonstrate enhanced serum neutralization activities promoted by allosteric dual site antagonists of HIV-1 Env gp120. Achievement of this milestone will lead to an R33 development phase that includes identification of advanced immunogens with optimized compositions of HIV-1 Env bound noncovalently and covalently to allosteric inhibitors (R33-Aim1); testing of immunogens using a non-human primate model with mucosal challenge (R33- Aim2); and production of potential neutralizing monoclonal antibodies, elicited by Env -allosteric inhibitor immunogens, that will be characterized for Env binding epitopes and breadth of neutralization (R33-Aim3). Overall, this project will use epitope focusing through conformational constraint to learn how allosteric ligands can exert control over conformations of HIV-1 Env protein in an immunogenically productive way, identify neutralization sites in HIV-1 Env for protective immunity, develop Env constructs for non-human primate efficacy/toxicity evaluation, and advance immunogen formulations to primate and, ultimately, human trials. PUBLIC HEALTH RELEVANCE: This project seeks to test newly identified forms of the HIV-1 virus coat protein as tools for designing AIDS vaccines that could be used to provide immunoprotection in humans.