Variation in HIV-1 R5 Envs: Consequences for tropism, neutralization & vaccines

HIV-1R5病毒在表型上有很大的差异，包括巨噬细胞嗜性和对 中和抗体。因此，高度嗜Mac的包膜(Env)利用低数量的CD4和/或CCR5 用于感染，并与需要高CD4水平和感染巨噬细胞的非嗜Mac R5环境形成对比 效率低下。高度嗜Mac的环境因子使用低CD4/CCR5的能力表明，这些变体可能 在其他表达低受体水平的CD4+细胞类型中提供更广泛的趋向性，并可能具有 在病毒传播过程中的优势。我们最新的数据，使用中和单抗和进入 抑制剂，强烈表明高度嗜Mac的R5env携带更多暴露的CD4结合位点(CD4bs) 并可能容易受到疫苗诱导的中和抗体(NAB)的影响。我们建议广泛地 研究不同的R5环境在以下四个目标中的趋向性和中和敏感性： 目的1.HIV-1R5巨噬细胞亲和性在不同CD4+细胞群感染中的作用。我们会 检查高度嗜Mac的R5包膜是否在CD4+T细胞群体中赋予更广泛的取向。 目的2.进一步分析巨噬细胞感染的包膜决定因素和低CD4在分支中的使用 B和非分支B信封。我们将分析分支B和非分支B环境以确定决定因素 并进一步研究CD4结合环的作用。 目的3.研究巨噬细胞趋化中R5环境蛋白变异对中和敏感性的影响 抗体。我们将研究R5环境基因变异如何影响对HIV-1+人血清的敏感性， 中和性单抗和疫苗诱导产生中和抗体。 目的4.细菌产生的、非糖基化的蛋白质结构的开发和特性 模仿CD4B。我们设计和生产了CD4BS模拟物，携带了 CD4bs是一种非糖基化的多肽，可在细菌中产生。这些CD4bs模拟结合CD4和 B12。将研究它们的结构和诱导中和抗体的能力。 我们期望对(1)R5envs的趋向性和中和性的变化提供重要的见解 敏感性，(2)与不同的嗜性和中和有关的环境氨基酸和结构决定因素 敏感性和(3)这种变异对新型包膜疫苗设计的影响。 相关性(请参阅说明)： 我们的应用程序建议对传播的HIV-1病毒如何在其 生物学特性。我们的数据将指导我们开发新型疫苗，旨在诱导 针对全球艾滋病毒-1的预防。

HIV-1 R5 viruses vary considerably in phenotypes, including macrophage-tropism and sensitivity to neutralizing antibodies. Thus, highly mac-tropic envelopes (envs) exploit low amounts of CD4 and/or CCR5 for infection and contrast with non-mac-tropic R5 envs that require high CD4 levels and infect macrophages inefficiently. The capacity of highly mac-tropic envs to use low CD4/CCR5 suggests that such variants may confer a broader tropism among other CD4+ cell types that express low receptor levels and may have an advantage during virus transmission. Our recent data, using neutralizing monoclonal antibodies and entry inhibitors, strongly suggests that highly mac-tropic R5 envs carry a more exposed CD4 binding site (CD4bs) and may be vulnerable to neutralizing antibodies (nabs) induced by vaccines. We propose to extensively investigate tropism and neutralization sensitivity of diverse R5 envs in the following four aims: Aim 1. The effect of HIV-1 R5 macrophage-tropism on infection of different CD4+ cell populations. We will examine whether highly mac-tropic R5 envelopes confer a broader tropism among CD4+ T-cell populations. Aim 2. Further analysis of the envelope determinants for macrophage infection and use of low CD4 in clade B and non-clade B envelopes. We will analyze clade B and non-clade B envs to identify determinants of tropism and to further examine the role of the CD4 binding loop. Aim 3. Investigation of the impact of R5 env variation in macrophage-tropism on sensitivity to neutralizing antibodies. We will investigate how R5 env variation impacts on sensitivity to HIV-1+ human sera, neutralizing mabs and vaccine induced neutralizing antibodies. Aim 4. Development and characterization of bacterially-produced, unglycosylated protein constructs that mimic the CD4bs. We have designed and produced CD4bs mimics that carry the critical elements of the CD4bs in an unglycosylated peptide that can be produced in bacteria. These CD4bs mimics bind CD4 and b12. Their structure and capacity to induce neutralizing antibodies will be investigated. We expect to provide important insights into (1) the variation of R5 envs for tropism and neutralization sensitivity, (2) the env amino acids and structural determinants involved in varying tropism and neutralization sensitivity and (3) the impact of this variation in the design of novel env-based vaccines. RELEVANCE (See instructions): Our application proposes an extensive investigation into how HIV-1 viruses that transmit vary in their biological properties. Our data will guide us in the development of novel vaccines designed to elicit protection against global HIV-1.