Structure/function studies of immunogen recognition by anti-HIV antibody b12

抗HIV抗体b12免疫原识别的结构/功能研究

基本信息

批准号：
8463117
负责人：
Roland K Strong
金额：
$ 57.18万
依托单位：
SEATTLE BIOMEDICAL RESEARCH INSTITUTE
依托单位国家：
美国
项目类别：
财政年份：
2013
资助国家：
美国
起止时间：
2013-05-01 至 2016-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/8463117
关键词：
AIDS Vaccines Affect Affinity Antibodies Antibody Binding Sites Antibody Formation Antigens Applied Research B-Cell Activation B-Lymphocytes Back Basic Science Binding Binding Sites Biological Assay Characteristics Complement Complex Crystallization Crystallography Data Development Engineering Epitopes Event Generations Goals HIV HIV Antibodies HIV Envelope Protein gp120 HIV Infections HIV vaccine Highly Active Antiretroviral Therapy Immune response Immune system Immunization Immunodominant Epitopes Immunoglobulin Somatic Hypermutation Immunology In Vitro Infection Kinetics Laboratories Lead Membrane Molecular Molecular Conformation Pharmaceutical Preparations Plasma Cells Process Property Proteins Receptor Signaling Receptors, Antigen, B-Cell Research Scaffolding Protein Structure Structure of germinal center of lymph node Testing Thermodynamics Vaccines Viral Viral Vaccines Virus Virus Diseases Virus Receptors Washington antigen binding base design feeding improved in vivo inhibiting antibody neutralizing antibody neutralizing monoclonal antibodies novel vaccines prevent prophylactic protein protein interaction response scaffold vaccine candidate vaccine development

项目摘要

Effective AIDS vaccines will likely need to elicit antibodies that can neutralize diverse strains of HIV, but vaccine immunogens based on soluble HIV Env constructs have, so far, failed to elicit such responses. Our first-generation attempts to design 'epitope-scaffold' antigens for bNAb 4E10 generate exquisite epitope-specific responses that, unfortunately, also fail to potently neutralize HIV. In order to improve on this approach (and embrace parallel strategies), we will now focus on the broadly neutralizing, CD4-binding site antibody b12. We propose to iteratively engineer b12-specific i) epitope-scaffolds and ii) minimized gp120 constructs, with binding optimized to both mature b12 and its germline precursor; the latter recognition event is essential for selectively activating the correct naive B cells that will lead to b12-equivalent responses. The biophysical parameters describing BCR/antigen interactions (affinities, kinetics, thermodynamics) have been shown to have profound effects on the course of humoral immune responses. We will test the hypothesis that i) b12 germline candidates will not completely recapitulate the binding, structural or neutralization properties of the mature antibody by some subset of the parameters that describe protein/protein interactions and function and ii) that, in order for designed immunogens to induce effective b12-like responses upon immunization, both immunogen/b12 and immunogen/germline interactions will need to be recapitulated. Since no single b12 germline precursor can confidently be identified, we propose to study the structures (using x-ray crystallography and small-angle x-ray scattering (SAXS)) and binding properties (using SPR and ITC) of an ensemble of the 12 likeliest candidates. Our proposed comprehensive biophysical studies of mature b12 and the complete ensemble of candidate b12 germline precursor antibodies will: i) support the rational immunogen redesign cycle in Project 1; ii) detail the molecular mechanisms of b12 maturation; and iii) provide the biophysical framework for interpreting the in vitro and in vivo B cell activation assays in Project 3. Our research goal is to understand the biophysical constraint/s on B cell activation thresholds for an epitope of one of the most potent and broadly anti-HlV-1 neutralizing MAbs known. We will then use these results to guide efforts to rationally design better immunogens to elicit anti-HIV NAbs while contributing significantly to the field of fundamental B cell immunology, combining basic and applied research goals.

有效的艾滋病疫苗可能需要引发能够中和多种艾滋病毒株的抗体，但迄今为止，基于可溶性艾滋病毒包膜结构的疫苗免疫原未能引发这种反应。我们第一代尝试为 bNAb 4E10 设计“表位支架”抗原，产生了精致的表位特异性反应，但不幸的是，也无法有效中和 HIV。为了改进这种方法（并采用并行策略），我们现在将重点关注广泛中和的 CD4 结合位点抗体b12。我们建议迭代地设计 b12 特异性 i) 表位支架和 ii) 最小化 gp120 构建体，并优化成熟 b12 及其种系前体的结合；后一个识别事件对于选择性激活正确的初始 B 细胞至关重要，从而导致 b12 等效反应。描述 BCR/抗原相互作用的生物物理参数（亲和力、动力学、热力学）已被证明对体液免疫反应过程具有深远的影响。我们将测试以下假设：i) b12 种系候选物不会完全重现结合、结构或中和通过描述蛋白质/蛋白质相互作用和功能的一些参数子集来确定成熟抗体的特性，并且ii)为了设计的免疫原在免疫后诱导有效的b12样反应，免疫原/b12和免疫原/种系相互作用都需要予以重述。由于无法自信地鉴定出单个 b12 种系前体，因此我们建议研究 12 种系前体的结构（使用 X 射线晶体学和小角 X 射线散射 (SAXS)）和结合特性（使用 SPR 和 ITC）最有可能的候选人。我们提出的综合生物物理学研究成熟的 b12 和候选 b12 种系前体抗体的完整集合将： i) 支持项目 1 中合理的免疫原重新设计周期； ii) 详细说明 b12 成熟的分子机制； iii) 提供生物物理框架，用于解释项目 3 中的体外和体内 B 细胞激活测定。我们的研究目标是了解最有效和最广泛的表位之一的 B 细胞激活阈值的生物物理限制。已知抗-HIV-1 中和单克隆抗体。然后，我们将利用这些结果来指导合理设计更好的免疫原以引发抗 HIV NAb，同时贡献结合基础和应用研究目标，对基础 B 细胞免疫学领域产生了重大影响。