Characterization of HIV-1 IgA bNAbs and ADCP function

项目摘要 HIV-1主要通过粘膜接触传播。IgA在粘膜分泌物中占主导地位，长期以来一直是一类 在入口处需要抗体来阻止感染。然而，由于缺乏伊加反应， HIV-1与IgG相比，以前的抗体分离工作和抗体库分析集中在 IgG+ B细胞和缺失的伊加+ B细胞。通过一种新的基于水泡性口炎病毒（VSV）的平台，我们展示了 膜包埋的HIV-1包膜（Env）三聚体用于探测Env特异性记忆B细胞并分离HIV-1 来自感染个体的广泛中和抗体（bNAb）。在此过程中，我们将伊加抗体 库分析并鉴定了两种HIV-1 bNAb谱系，其类别转换为IgG和伊加，因此对于 首次鉴定出HIV-1自然感染过程中产生的真正伊加bNAb。此外，我们还分离出 两种Env导向的伊加单克隆抗体（mAb）表现出部分病毒中和和有效的免疫抑制作用， 抗体依赖性细胞吞噬作用（ADCP）的功能是消除HIV-1感染的细胞。作为最近的VRC 01 预防试验显示没有总体疗效，对VRC 01敏感菌株的疗效仅为75%，因此需要 改善bNAb介导的预防。考虑到粘膜SIgA的独特性质，如二聚化， 稳定性和对酶降解的抗性，我们旨在测试伊加（二聚体）bNAb被动输注是否 比IgG更能阻断感染在这些科学前提的支持下，需要改善bNAb- 介导的预防，我们建议从外周血中鉴定出额外的HIV-1伊加bNAb和ADCP伊加mAb， 进化枝B和非进化枝B感染个体的血液，包括纵向跟踪的个体，以及来自乳房的血液 来自BAN队列的HIV进化枝C感染母亲的乳细胞（目的1），然后在结构上定义和表征 伊加靶向表位（目的2），最后使用IgG bNAb检测代表性伊加bNAb和ADCP伊加 作为基准，用于恒河猴SHIV粘膜攻击模型中的保护功效（目的3）。我们的目标是 检验以下假设：1）在全身和粘膜中引起显著的伊加bNAb和ADCP应答 2）伊加bNAb和ADCP IgA可能靶向不同于HIV-1感染期间的抗原表位。 先前已知的IgG bNAb; 3）伊加bNAb与其IgG bNAb对应物相当或更好地保护 ADCP伊加对SHIV粘膜攻击也有保护作用。如果成功， 该项目将揭示并验证伊加在对抗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.