HIV-2 Env Variable Loop Deletions as HIV-1 Vaccines

HIV-2 Env 可变环缺失作为 HIV-1 疫苗

• 批准号: 7035890
• 负责人: GEORGE LIN
• 金额: $ 28.12万
• 依托单位: BIOLOGICAL MIMETICS, INC.
• 依托单位国家: 美国
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-04-01 至 2007-09-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7035890
• 关键词: AIDS vaccines; CD4 molecule; HIV envelope protein gp120; chemokine receptor; gene deletion mutation; genetic manipulation; human immunodeficiency virus 1; human immunodeficiency virus 2; neutralizing antibody; protein structure function; receptor binding; virus envelope

DESCRIPTION (provided by applicant): HIV is extremely adept in evading humoral immunity. Although neutralizing antibodies (NAbs) are produced to the viral envelope glycoprotein (Env), they are characteristically directed to hypervariable loops on gp120 (V1/V2 and V3), which can tolerate extensive genetic variation. Thus, these NAbs are generally "type specific" and not broadly neutralizing. In addition, the variable loops protect highly conserved functional domains on the gp120 core, i.e. binding sites for CD4 and chemokine receptors (CCR5 and CXCR4). Using CD4-independent Envs, we have derived replication competent variants of HIV-2 that lack V1/V2 and V3 hypervariable loops. Although viruses without V1/V2 have been described for HIV-1 and SIV, no virus to date has tolerated deletions in V3; V3 has been considered indispensable for Env function and coreceptor binding. Given the role of V1/V2 and V3 in protecting core domains from humoral immune responses, we hypothesize that Envs from these "minimized," loop-deleted viruses may have the potential to elicit novel antibodies to conserved and functional epitopes on gp120. Moreover, we hypothesize that Envs from CD4-independent HIV isolates represent a transition state in the Env-fusion cascade with exposed receptor binding regions and decreased conformational flexibility, properties that may be desirable in generating neutralizing antibodies. Thus, CD4-independent Envs with strategic removal of structures prohibitory to effective neutralizing antibody elicitation without altering Env function may allow derivation of a better immunogen that is able to elicit broadly neutralizing antibodies and "immune refocus" these antibodies towards key functional regions on Env. Our work has been focused on extending our findings to HIV-1 Envs such that they may be applied to HIV-1 vaccine development. Instead of taking a direct approach of generating HIV-1 Envs with hypervariable loop deletions, we explore here the feasibility of introducing HIV-1 converting mutations at receptor binding regions and/or epitopes for key anti-HIV-1 NAbs into our fully-functional hypervariable loop deleted HIV-2 Envs to generate functional, loop deleted "HIV-1 like" Envs for future HIV-1 vaccine studies. Two Specific Aims are proposed: #1) engineer HIV-1 converting mutations into wildtype HIV-2/vcp Env and functional, hypervariable loop deleted derivatives and assess for retention of functionality and #2) determine the reactivity of key anti-HIV-1 neutralizing MAbs (b12, CD4i MAbs, 2F5, and 4E10) to wildtype HIV-2/vcp Env and hypervariable loop derivatives with HIV-1 converting mutations.

描述（由申请人提供）：HIV 非常擅长逃避体液免疫。尽管中和抗体 (NAb) 是针对病毒包膜糖蛋白 (Env) 产生的，但它们的特征是针对 gp120（V1/V2 和 V3）上的高变环，该环可以耐受广泛的遗传变异。因此，这些NAb通常是“类型特异性的”并且不具有广泛的中和作用。此外，可变环保护 gp120 核心上高度保守的功能域，即 CD4 和趋化因子受体（CCR5 和 CXCR4）的结合位点。使用不依赖 CD4 的 Env，我们衍生出了缺乏 V1/V2 和 V3 高变环的 HIV-2 复制能力变体。尽管没有 V1/V2 的病毒已被描述为 HIV-1 和 SIV，但迄今为止还没有病毒能够容忍 V3 的缺失。 V3 被认为对于 Env 功能和辅助受体结合是不可或缺的。鉴于 V1/V2 和 V3 在保护核心结构域免受体液免疫反应中的作用，我们假设来自这些“最小化”的环删除病毒的 Env 可能有潜力引发针对 gp120 上保守和功能性表位的新抗体。此外，我们假设来自CD4独立HIV分离株的Env代表了Env融合级联中的过渡状态，其具有暴露的受体结合区域和降低的构象灵活性，这些特性可能是产生中和抗体所需要的。因此，在不改变 Env 功能的情况下，战略性地去除抑制有效中和抗体引发的结构的不依赖于 CD4 的 Env 可能会产生更好的免疫原，该免疫原能够引发广泛的中和抗体并将这些抗体“免疫重新聚焦”到 Env 上的关键功能区。我们的工作重点是将我们的发现扩展到 HIV-1 环境，以便将它们应用于 HIV-1 疫苗的开发。我们没有采取直接方法生成具有高变环删除的 HIV-1 包膜，而是在此探索将关键抗 HIV-1 NAb 的受体结合区和/或表位处的 HIV-1 转换突变引入我们的全功能的可行性。高变环删除的 HIV-2 包络体可生成功能性、环路删除的“HIV-1 样”包络体，用于未来的 HIV-1 疫苗研究。提出了两个具体目标：#1) 将 HIV-1 突变转化为野生型 HIV-2/vcp Env 和功能性高变环删除衍生物，并评估功能的保留；#2) 确定关键抗 HIV-1 的反应性中和单克隆抗体（b12、CD4i 单克隆抗体、2F5 和 4E10）与野生型 HIV-2/vcp Env 和具有 HIV-1 转换突变的高变环衍生物。