Determinants of Neutralization Breadth in Early HIV-1 Infection

描述（由申请方提供）：诱导中和（nAb）循环HIV-1毒株的抗体的能力对于疫苗显示出最佳的抗HIV-1保护效力至关重要。为了确定可以刺激这些反应的表位，已经从少数表现出上级血浆nAb的慢性感染个体中回收了具有广泛和有效中和能力的单克隆抗体（mAb），但是尚未确定在这种广泛和有效中和表型之前的病毒和宿主B细胞事件。早期感染的样本尚未从这些广泛中和的个体中获得，因此关于nAb宽度如何发展的问题尚不能回答。在这里，我们确定了5个亚型A和C HIV-1感染的血清转换者，在17个，谁开发相对有效的交叉分支的nAb宽度在感染后3年。这项提案将调查如何以及为什么nAb广度在这些人中发展，而不是在其他人中具有低或不可检测的广度水平。我们的初步数据表明，这两个患者群体之间存在根本的病毒学和免疫差异，这可以解释为什么早期nAb是菌株特异性的，但后来nAb在一个受试者亚组中继续发展异源宽度。这种对早期感染的关注与nAb宽度通常存在或不存在的观察结果一致。 感染后约3年。此外，我们的初步数据显示，来自我们的组中的广泛中和剂的自体nAb靶向V1 V2和CD 4结合位点，这两个靶标都是具有“精英”异源中和活性的mAb的靶标。我们将利用储存的血浆和活PBMC样本，在5例具有nAb宽度的受试者和5例不具有nAb宽度的受试者中确定初始nAb靶标和病毒逃逸途径。我们将使用包膜（Env）gp 140 B细胞探针从单B细胞分选中回收mAb，并从这10例受试者中在两个早期时间点和感染后约3年采集PBMC样本。mAb将在遗传和功能上进行表征，并且还将结晶出代表性子集，包括具有广度的子集。 据我们所知，尚未对中和宽度的早期病毒和免疫决定因素进行此类比较研究。拟议的目标还提供了回收和表征广泛中和mAb的强烈可能性，这些mAb可能代表从慢性感染中分离出来的早期版本。我们的假设是，初始靶向某些nAb表位，如CD 4结合位点或V1 V2，结合逃逸途径的后续影响，导致在HIV-1感染个体的子集中nAb宽度的发展。具体而言，目的是（i）确定初始中和抗体靶标，并确定5例出现异源中和宽度的近期感染受试者和5例缺乏宽度的受试者的病毒逃逸途径，以及（ii）确定菌株特异性和获得自体或异源中和宽度的早期mAb的基因型、功能和结构特征。

DESCRIPTION (provided by applicant): The ability to induce antibodies that neutralize (nAb) circulating HIV-1 strains will be critical for a vaccine to exhibit optimal protective efficacy aganst HIV-1. To define the epitopes that can stimulate these responses, monoclonal antibodies (mAb) with broad and potent neutralization capacity have been recovered from a few chronically infected individuals that exhibited superior plasma nAb, but the viral and host B cell events that preceded this broad and potent neutralization phenotype have not been defined. Samples from early infection have not been available from these broadly neutralizing individuals, so questions about how nAb breadth developed cannot yet be answered. Here we identified 5 subtype A and C HIV-1 infected seroconvertors, out of 17, who developed relatively potent cross-clade nAb breadth at ~3 years post-infection. This proposal will investigate how and why nAb breadth developed in these individuals, but not in others who had low or undetectable levels of breadth. Our Preliminary Data suggest that there are fundamental virologic and immune differences between these two patient populations that could explain why early nAb are strain-specific, but later nAb go on to develop heterologous breadth in a subset of subjects. This focus on early infection is consistent with the observation that nAb breadth is generally either present or absent by ~3 years post-infection. Furthermore, our Preliminary Data show that autologous nAb from broad neutralizers in our panel targeted V1V2 and the CD4 binding site, both targets of mAbs with 'elite' heterologous neutralizing activity. We will utilize stored plasma and viable PBMC samples to define the initial nAb targets and viral escape pathways in 5 subjects with nAb breadth and 5 subjects without. We will recover mAbs from single B cell sorts using envelope (Env) gp140 B cell probes and PBMC samples collected at two early time points, and ~3 years post-infection, from these 10 subjects. The mAbs will be characterized genetically and functionally, and a representative subset, including those with breadth, will also be crystallized. To our knowledge, this type of comparative investigation into the early viral and immune determinants of neutralization breadth has not been performed. The proposed aims also provide a strong likelihood of recovering and characterizing broadly neutralizing mAbs that could represent early versions of those isolated from chronic infection. Our hypothesis is that the initil targeting of certain nAb epitopes, such as the CD4 binding site or V1V2, combined with the subsequent influence of escape pathways, leads to the development of nAb breadth in a subset of HIV-1 infected individuals. Specifically, the aims are to (i) Identify the initial neutralizing antibody target and define the viral escape pathways in 5 recently infected subjects who developed heterologous neutralization breadth and 5 subjects that lack breadth and (ii) Determine the genotypic, functional, and structural characteristics of early mAbs that are strain-specific and those that have acquired autologous or heterologous neutralization breadth.