Discovery of Novel Epitopes for Antibody Dependent Cell-mediated Cytotoxicity Against HIV-1 Infected Cells

项目概要/摘要 HIV 研究工作的重点是开发能够引发高度保护性抗体的疫苗 回应。人类和非人类疫苗研究的证据表明，中和疫苗和非疫苗 中和抗体活性有助于防止获得。重要的是，唯一的 III 期疫苗 在人类志愿者中显示保护信号的功效试验表明，抗体依赖性细胞- 介导的细胞毒性（ADCC）与获取减少相关，迫使我们更多地了解这一点 Fc介导的抗病毒功能。我们之前回收了 300 多个单克隆抗体的独特集合 来自赞比亚和卢旺达的 6 名最近感染 HIV-1 的人的抗体，发现其中的一部分 抗体介导针对涂有来自自体的包膜 gp120 蛋白的靶细胞的 ADCC， 传播/创始人（T/F）变体。此活性与具有较短 CDRH3 区域的抗体相关 与缺乏 ADCC 活性的抗体相比，针对 T/F 包膜假病毒的中和活性较低。 建模和竞争研究表明，一些 ADCC 介导的抗体可识别新的 表位。在这里，我们将测试这些单克隆抗体针对被真实病毒感染的靶细胞的 ADCC 通过分子克隆创建 T/F 变体，并将结果与 ADCC 与涂有 T/F 的靶细胞进行比较 T/F gp120 蛋白和 T/F Env 的中和，后者是抗体与 T/F Env 结合的标志 功能性的、与病毒粒子相关的包膜刺突。通过使用大量自体T/F包膜抗体 组合，其中包膜呈现精确的表位或非常接近于 抗体被选择针对，以及两种广泛使用的 ADCC 检测，我们的研究有可能揭示 以前未被认识的 ADCC 机制特征，并确定可以进一步研究的新表位 开发和探索疫苗。

Project Summary/Abstract HIV research efforts are strongly focused on developing vaccines that can elicit highly protective antibody responses. There is evidence from human and nonhuman vaccine studies that both neutralizing and non- neutralizing antibody activities contribute to protection against acquisition. Importantly, the only phase III vaccine efficacy trial to show a signal of protection in human volunteers demonstrated that antibody dependent cell- mediated cytotoxicity (ADCC) was associated with reduced acquisition, compelling us to know more about this Fc-mediated antiviral function. We previously recovered a unique collection of more than 300 monoclonal antibodies from 6 recently HIV-1 infected individuals from Zambia and Rwanda and found that a subset of these antibodies mediated ADCC against target cells coated with the envelope gp120 protein from the autologous, transmitted/founder (T/F) variant. This activity was associated with antibodies that had shorter CDRH3 regions and lower neutralization activity against the T/F envelope pseudovirus than antibodies lacking ADCC activity. Modeling and competition studies suggested that some of the ADCC-mediating antibodies recognize novel epitopes. Here, we will test these monoclonal antibodies for ADCC against target cells infected with the authentic T/F variant created by molecular cloning, and compare the results with ADCC against target cells coated with the T/F gp120 protein and neutralization of the T/F Env, the latter being the hallmark of antibody binding to the functional, virion-associated envelope spike. By using a large number of autologous T/F envelope-antibody combinations, where the envelope presents the exact epitope or a very close approximation to that which the antibody was selected against, and two widely used ADCC assays, our studies have the potential to reveal previously unappreciated mechanistic features of ADCC and identify novel epitopes that can be further developed and explored for vaccines.