Immunogenicity of the newly identified V3 crown vulnerable site

新发现的 V3 冠脆弱位点的免疫原性

• 批准号: 10548294
• 负责人: XIANGPENG KONG
• 金额: $ 27.06万
• 依托单位: NEW YORK UNIVERSITY SCHOOL OF MEDICINE
• 依托单位国家: 美国
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-07-05 至 2024-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10548294
• 关键词: Animals; Antibodies; Antibody Response; Antigens; Area; B-Lymphocytes; Binding; Biological Assay; Blood specimen; Categories; Characteristics; Cryoelectron Microscopy; Dental crowns; Enzyme-Linked Immunosorbent Assay; Epitope Mapping; Epitopes; Foundations; Future; Genes; Glycoproteins; Goals; HIV; HIV Envelope Protein gp120; HIV vaccine; HIV-1; Human; Immunization; Immunoglobulin A; Immunoglobulin Class Switching; Immunoglobulin G; Location; Maps; Membrane Proteins; Modeling; Modification; Molecular Target; Monoclonal Antibodies; Mus; N-terminal; Negative Staining; Oryctolagus cuniculus; Outcome; Patients; Polysaccharides; Regimen; Site; Structure; Surface; Testing; V3 Loop; Vaccines; Virus; beta pleated sheet; design; disulfide bond; immunogenic; immunogenicity; neutralizing antibody; nonhuman primate; novel; pathogen; purge; rational design; response; scaffold; screening; vaccination strategy; virus envelope

To be able to induce antibody (Ab) responses against the HIV-1 envelope (Env) spike vulnerable sites defined by broadly neutralizing antibodies (bnAbs) will likely lead to a protective vaccine. Many HIV bnAbs have been discovered and their epitopes have been carefully mapped on the surface of Env, and these epitopes have been categorized into a number of well characterized classes. However, a consistently induction of bnAb responses targeting any of those currently well characterized vulnerable sites is still extremely difficult because of the unusual features of these bnAbs and their associated vulnerable sites, such as the requirement of a long CDR H3 to penetrate the glycan shield of the Env spike. Thus, identification of additional vulnerable sites with more favorable characteristics for rational targeting may help to increase our capability of induction of bnAb responses. We have identified recently a new vulnerable site by mapping the epitope of bnAb M4008_N1 and characterizing its antibody-antigen interaction. M4008_N1 is a bnAb that can neutralize about 40% of the primary isolates tested and its lineage class-switched to both IgG and IgA. We showed that by cryo-EM the epitope of M4008_N1 is centered at the crown region of the third variable loop (V3) of gp120 in the prefusion Env trimer. The unique characteristics of the M4008_N1 epitope and its mode of interaction with the V3 crown suggest a strategy to induce M4008_N1-like Ab responses by a V3 priming and heterologous boosting with stabilized Env trimer. As we have demonstrated previously, the V3 crown Ab responses are relatively straightforward to elicit by V3 immunogens. We therefore hypothesize that, since the V3 crown -hairpin is a common structure and M4008_N1 can bind V3 loop itself, antibodies that engage the N-terminal strand by a β- sheet interaction, like that of M4008_N1, can be induced by V3 immunogens, and such M4008_N1-like antibody responses can then be boosted with a subsequent immunization with a V3-stabilized Env trimer, which harbors the whole epitope of bnAb M4008_N1. Early versions of the SOSIP immunogens were known to induce non-neutralizing V3 antibodies, but some V3-stabilized versions seemed to be able to purge non- neutralizing V3 antibody responses. These V3-stabilized SOSIP trimers can therefore be used for the heterologous boost to induce M4008_N1-like antibody responses. We will test our hypothesis in a rabbit model using a set of carefully selected to be optimal in the heterologous prime/boost strategy, and we have two Aims. (1) Selection of the best immunogen combination, (2): Rabbit immunization and characterization of the antibody responses. The expected outcome of this project is a proof of principle demonstration for the immunogenicity targeting the newly identified V3 crown vulnerable site and to lay a foundation for future extensive immunogenicity studies including potentially non-human primate studies.

能够诱导针对定义的 HIV-1 包膜 (Env) 尖峰脆弱位点的抗体 (Ab) 反应 通过广泛中和抗体（bnAbs）可能会产生保护性疫苗。许多 HIV bnAb 已被 发现了它们的表位，并已在 Env 表面仔细绘制了图谱，这些表位已 被分为许多特征明确的类别。然而，持续诱导 bnAb 针对任何目前已明确描述的易受攻击站点的响应仍然极其困难，因为 这些 bnAb 的不寻常特征及其相关的脆弱位点，例如需要长 CDR H3 穿透 Env 刺突的聚糖屏蔽。因此，识别其他易受攻击的站点 更有利的合理靶向特性可能有助于提高 bnAb 的诱导能力 回应。我们最近通过绘制 bnAb M4008_N1 的表位和 表征其抗体-抗原相互作用。 M4008_N1 是一种 bnAb，可以中和约 40% 测试的原代分离株及其谱系类别均转换为 IgG 和 IgA。我们通过冷冻电镜证明 M4008_N1 的表位集中在预融合中 gp120 的第三个可变环 (V3) 的顶部区域 环境三聚体。 M4008_N1表位的独特特征及其与V3冠的相互作用模式 建议通过 V3 引发和异源加强来诱导 M4008_N1 样抗体反应的策略 稳定的环境三聚体。正如我们之前所证明的，V3 冠抗体反应相对 直接由 V3 免疫原引发。因此我们假设，由于 V3 冠  发夹是 共同结构和 M4008_N1 可以结合 V3 环本身，抗体通过 β- 接合 N 端链 像 M4008_N1 一样，片层相互作用可以由 V3 免疫原诱导，并且这种 M4008_N1 样 然后可以通过使用 V3 稳定的 Env 三聚体进行后续免疫来增强抗体反应， 它包含 bnAb M4008_N1 的整个表位。众所周知，SOSIP 免疫原的早期版本 诱导非中和性 V3 抗体，但一些 V3 稳定版本似乎能够清除非中和性 V3 抗体。 中和 V3 抗体反应。因此，这些 V3 稳定的 SOSIP 三聚体可用于 异源加强诱导 M4008_N1 样抗体反应。我们将在兔子模型中检验我们的假设 使用一组精心挑选的异源启动/增强策略中的最佳策略，我们有两个目标。 (1) 最佳免疫原组合的选择，(2)：兔免疫和表征 抗体反应。该项目的预期成果是原理论证的证明 针对新发现的V3冠脆弱位点的免疫原性，为未来奠定基础 广泛的免疫原性研究，包括潜在的非人类灵长类动物研究。