Characterization of HIV-1 IgA bNAbs and ADCP function

项目总结 HIV-1主要通过粘膜接触传播。在粘膜分泌物中占主导地位的是IgA，长期以来一直是 在入口的入口处需要抗体以阻断感染。然而，由于缺乏免疫球蛋白A对 与免疫球蛋白相比，以前的抗体分离努力和抗体谱系分析主要集中在 免疫球蛋白G+B细胞和缺失的免疫球蛋白A+B细胞。利用一种基于水疱性口炎病毒(VSV)的新型平台，我们展示了 膜包埋HIV-1包膜三聚体探测包膜特异性记忆B细胞及分离HIV-1 来自感染者的广谱中和抗体(BNAbs)。在这个过程中，我们包括了IgA抗体 谱系分析和鉴定了两个HIV-1 bNAb谱系，它们同时转换为免疫球蛋白和免疫球蛋白A，从而为 首次鉴定出HIV-1自然感染过程中产生的真正的IgA bNAbs。此外，我们已经分离出 两个显示部分病毒中和和有效的包膜导向的IgA单抗 抗体依赖的细胞吞噬作用(ADCP)具有清除HIV-1感染细胞的功能。作为最新的VRC01 预防试验显示，对VRC01敏感株没有总体疗效，只有75%的有效率，它呼吁 改进了bNAb介导的预防。鉴于粘膜SIgA的独特性质，如二聚化，高 稳定性和对酶降解的抵抗力，我们的目的是测试IgA(二聚体)bNAb被动输注是否 在阻断感染方面优于免疫球蛋白。在这些科学前提和改进bNAb的必要性的支持下- 介导性预防，我们建议从外周血中识别额外的HIV-1 IgA bNAbs和ADCP IgA mAb B型分支和非B型分支感染者的血液，包括纵向追踪的和来自乳房的 来自禁令队列(目标1)的C类艾滋病毒感染母亲的乳细胞，然后从结构上定义和表征 Ig A靶向表位(Aim 2)，最后用Ig G b NAb检测具有代表性的Ig A bNAb和ADCP Ig A 作为基准，用于恒河猴Shiv黏膜攻击模型的保护效果(目标3)。我们的目标是 检验以下假设：1)在全身和粘膜中可诱发显著的IgA、bNAbs和ADCP反应 在HIV-1感染过程中的间隔；2)IgA bNAbs和ADCP Igas可能针对不同于HIV-1感染的表位 已知的Ig G bNAb；3)Ig A b NAb可与其对应的Ig G bNAb相媲美或更好地保护 抗SIV黏膜攻击，ADCP IgA对SIV黏膜攻击也有保护作用。如果成功， 该项目将揭示并验证IgA在对抗HIV-1方面的潜在抗病毒功能。

PROJECT SUMMARY HIV-1 spreads mainly through mucosal exposures. Dominant in mucosal secretions, IgA has long been the class of antibodies desired at the portal of entrance to block infection. However, due to a paucity of IgA responses to HIV-1, compared to IgG, previous antibody isolation efforts and antibody repertoire analyses have focused on IgG+ B cells and missed IgA+ B cells. With a novel vesicular stomatitis virus (VSV)-based platform, we displayed the membrane-embedded HIV-1 envelope (Env) trimer to probe Env-specific memory B cells and isolate HIV-1 broadly neutralizing antibodies (bNAbs) from infected individuals. During this process, we included IgA antibody repertoire analyses and identified two HIV-1 bNAb lineages that class-switched to both IgG and IgA, thus for the first time identified bona fide IgA bNAbs produced during HIV-1 natural infection. Additionally, we have isolated two Env-directed IgA monoclonal antibodies (mAbs) that exhibited partial virus neutralization and potent antibody-dependent cellular phagocytosis (ADCP) function to eliminate HIV-1-infected cells. As recent VRC01 prevention trials showed no overall efficacy and only 75% efficacy to VRC01-sensitive strains, it calls for improved bNAb-mediated prevention. Given the unique properties of mucosal SIgA, such as dimerization, high stability, and resistance to enzymatic degradation, we aim to test whether IgA (dimer) bNAb passive infusion is better than IgG to block infection. Supported by these scientific premises and the need to improve bNAb- mediated prevention, we propose to identify additional HIV-1 IgA bNAbs and ADCP IgA mAbs from peripheral blood of clade-B and non-clade-B infected individuals, including those followed longitudinally, and from breast milk cells of HIV clade C infected mothers from the BAN cohort (Aim 1), then structurally define and characterize the IgA targeted epitopes (Aim 2), and finally test a representative IgA bNAb and ADCP IgA, using an IgG bNAb as benchmark, for protection efficacy in a rhesus macaque SHIV mucosal challenge model (Aim 3). We aim to test the hypothesis that 1) significant IgA bNAbs and ADCP responses are elicited in systemic and mucosal compartments during HIV-1 infection; 2) IgA bNAbs and ADCP IgAs may target epitopes distinct from those of previously known IgG bNAbs; 3) IgA bNAb is comparable to or better than its IgG bNAb counterpart to protect against SHIV mucosal challenge, and ADCP IgA may also protect from SHIV mucosal challenge. If successful, the project will unveil and validate the potential antiviral functions of IgA to fight against HIV-1.