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HIV-1包膜（Env）蛋白的结构约束形式，用于HIV-1疫苗的开发。病毒包膜蛋白gp120的配方可以编程人体免疫系统识别和阻断HIV-1包膜蛋白，这是艾滋病疫苗开发的主要目标。然而，gp120已经被发现能够逃避免疫监视，这主要是由于它的构象灵活性。确定诱导结构稳定性增加的方法，特别是通过保守表位聚焦，被视为提高包膜疫苗引发中和性免疫反应能力的重要目标。最近，我们开发了一组称为“变构双位点拮抗剂”的分子，它们可以与病毒gp120强烈结合，从而将gp120捕获在一个三维结构中，该结构在功能上受到抑制，但具有可访问的CD4 Phe 43结合袋。我们假设变构双位点拮抗剂可以诱导改变HIV-1包膜蛋白的免疫原性景观，并且这种改变的景观可能导致对保守受体结合位点（包括CD4）的增强中和免疫反应。我们将在这个PIA项目的R21阶段测试这个假设，有两个主要目标。利用重组蛋白工程和多肽合成技术，我们的目标是生产HIV-1 Env免疫原，其中HNG-156类的变构双位点拮抗剂与HIV-1 gp120的重组三聚体和单体形式非共价或共价结合。（R21-Aim2）通过小动物模型，我们的目的是验证这样的假设，即变构gp120抑制剂与重组三聚体和单聚体形式的HIV-1 gp120的复合物和共价融合疫苗接种会增强抗hivgp120特异性抗体和T细胞表位的宽度、大小和B细胞的中和能力。R21项目的关键里程碑将是证明HIV-1 Env gp120的变构双位点拮抗剂促进了血清中和活性的增强。

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.