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

项目概要/摘要 艾滋病毒研究工作主要集中在开发能够引发高度保护性抗体的疫苗上 应答来自人类和非人类疫苗研究的证据表明， 中和抗体活性有助于防止感染。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）与获得减少有关，迫使我们对此了解更多 Fc介导的抗病毒功能。我们以前回收了一个独特的收集超过300单克隆 来自赞比亚和卢旺达的6名最近感染HIV-1的人的抗体，发现这些抗体的一个子集 抗体介导的ADCC针对包被有来自自体的包膜gp 120蛋白的靶细胞， transmitted/founder（T/F）variant.这种活性与具有较短CDRH 3区域的抗体相关 和对T/F包膜假病毒的中和活性低于缺乏ADCC活性的抗体。 建模和竞争研究表明，一些ADCC介导的抗体识别新的 表位在这里，我们将测试这些单克隆抗体的ADCC对靶细胞感染的真实 通过分子克隆产生T/F变体，并将结果与ADCC对包被有 T/F gp 120蛋白和T/F Env的中和，后者是抗体结合T/F gp 120蛋白的标志。 功能性的病毒体相关包膜尖峰利用大量自体T/F结合抗体， 组合，其中所述包膜呈现精确的表位或非常接近于所述包膜所呈现的表位。 抗体的选择，以及两个广泛使用的ADCC测定，我们的研究有可能揭示 ADCC以前未被认识的机制特征，并鉴定可以进一步 开发和研究疫苗。

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.