Characterizing HIV-1 Env conformations susceptible to attack by non-neutralizing antibodies

总结 虽然目前的抗逆转录病毒疗法（ART）能够控制艾滋病毒的复制，但它们无法完全恢复 健康或正常的免疫状态。ART治疗的个体仍然会出现几种合并症，包括 增加心血管疾病、骨骼疾病和认知障碍。最重要的是，治疗 中断导致病毒复制的重新出现和发展为AIDS。因此，新方法 旨在根除或功能性治愈HIV感染的药物是迫切需要的。一个研究不足的战略， 在病毒再活化后消除潜伏感染的细胞依赖于免疫细胞介导抗体的能力， 依赖性细胞毒性（ADCC）。在泰国进行的RV 144 HIV-1疫苗试验获得了31.2%的保护率， 这是第一个在产生保护性反应方面取得任何程度成功的疫苗试验。后续 分析表明，这种适度的保护作用与高表达抗体（Abs）的产生有关。 ADCC活性，在低血浆伊加Env特异性Ab存在下。这表明ADCC可能具有 有助于RV 144试验中观察到的保护作用。但关键的未解之谜存在， 研究人员从专门触发ADCC反应与新的治疗或免疫原：为什么 RV 144试验产生如此强烈的ADCC反应？HIV-1的CRF01_AE亚型， 在泰国艾滋病流行中占主导地位，可能使其特别容易受到ADCC的影响？Env构象是否 影响ADCC反应？研究这些问题将证明对设计改进的战略至关重要， 消除HIV-1感染细胞。本提案中所述研究的长期目标是告知 制定新战略，利用ADCC反应根除HIV-1感染。实现这一 为了达到这一目标，我们将开始从分子上详细描述易受抗体攻击的Env构象 并确定来自不同HIV-1毒株的Env的结构元件， 转变为这些构象。我们的中心假设是，Env具有内在的下游通路， 这些构象被容易引发的非中和Ab识别。其中一些，比如反簇A Abs具有强的ADCC活性。为了支持这一假设，我们最近证明了使用抗体结合 冷冻电子显微镜（Cryo-EM）和单分子Förster共振能量转移（smFRET） 想象HIV-1 Env可以采取对具有有效ADCC的Ab攻击敏感的构象， 活动（状态2A）。这一提议的基本原理是环境状态结构的描述 2A，以及由非中和Ab识别的其他构象的威尔斯，以及介导 这些构象的稳定将为消除潜伏的HIV储存库的新策略提供信息。

SUMMARY While current antiretroviral therapies (ART) are able to control HIV replication, they are unable to fully restore health or a normal immune status. ART-treated individuals still experience several co-morbidities including increased cardiovascular disease, bone disorders, and cognitive impairment. Most importantly, therapy interruption leads to the re-emergence of viral replication and progression to AIDS. Therefore, new approaches aimed at eradicating or functionally curing HIV infection are desperately needed. An under-studied strategy to eliminate latently infected cells after viral reactivation relies on the ability of immune cells to mediate antibody- dependent cellular cytotoxicity (ADCC). The RV144 HIV-1 vaccine trial in Thailand elicited a 31.2% protective efficacy, making it the first vaccine trial with any level of success in generating a protective response. Subsequent analyses indicated that this modest protection was correlated with the generation of antibodies (Abs) with high ADCC activity, in the presence of low plasma IgA Env-specific Abs. This suggests that ADCC may have contributed to the protection observed in the RV144 trial. But key unanswered questions exist that prevent researchers from specifically triggering the ADCC response with novel treatments or immunogens: Why did the RV144 trial generate such a strong ADCC response? What about the CRF01_AE subtype of HIV-1, which predominates the Thai AIDS epidemic, might make it especially susceptible to ADCC? Does Env conformation affect ADCC responses? Answering these questions will prove crucial to the design of improved strategies to eliminate HIV-1-infected cells. The long-term goal of the research described in this proposal is to inform the development of new strategies for utilizing the ADCC response to eradicate the HIV-1 infection. To achieve this goal, we will begin by describing in molecular detail the Env conformations that are susceptible to attack by Abs that induce ADCC, and to determine the structural elements of Env from distinct HIV-1 strains that mediate transition to these conformations. Our central hypothesis is that Env has intrinsic access to downstream conformations that are recognized by easily-elicited non-neutralizing Abs. Some of which, like the anti-cluster A Abs, have potent ADCC activity. In support of this hypothesis, we recently demonstrated using Ab-binding assays, cryo-electron microscopy (Cryo-EM), and single-molecule Förster resonance energy transfer (smFRET) imaging that HIV-1 Env can adopt a conformation that is sensitive to attack by Abs that have potent ADCC activity (State 2A). The rationale underlying this proposal is that characterization of the structure of Env State 2A, as wells as other conformations recognized by non-neutralizing Abs, and the elements that mediate stabilization of these conformations will inform new strategies to eliminate the latent HIV reservoir.