Expansion and targeted maturation of germline HIV-1 bNAb-associated BCRs

摘要 通过免疫诱导有效和广泛的HIV-1中和抗体(BNAbs)一直是 自艾滋病毒/艾滋病流行开始以来，艾滋病毒-1疫苗研究的主要目标。在过去的十年里， 重大的技术和概念进步使得能够隔离和详细描述一个 来自HIV-1感染者的过多新的bNAb。这种抗体的结构特征， 结合它们个体发育的信息，极大地提高了我们对这些抗体如何 是在自然感染期间产生的，这导致了关于如何通过 免疫接种。我们的HIVRAD计划赠款旨在测试新试剂和主要加强免疫 诱导VRC01类bNAb的方案，这是最广泛和最有效的HIV-1中和方案之一 抗体已知，并在动物研究中显示出令人印象深刻的保护潜力。然而，中国的发展 通过免疫接种VRC01类bNAbs需要克服几个障碍。一位成功的 免疫接种计划可能至少需要提供新的免疫原来启动和 指导bNAb成熟进程，制定将扩张降至最低的战略 竞争脱靶的B细胞，开发最佳的Boost环境免疫原来引导适当的 抗体成熟，并提供持续的T辅助反应。在这里，我们建议测试概念，而不是 以前测试过的，我们已经开发出来直接解决这些问题。我们将评估一项新战略 是基于使用我们针对生殖系VRC01产生的抗独特型单抗(AiMAbs)- BCR类。我们的初步数据表明，这些aiMAb特异性地扩增表达 胚系VRC01-类B细胞受体(BCR)和这些细胞进入生发中心(GC)反应 并在环境免疫后进一步扩大。一个明显的优势是GC的更大扩展 想要的B细胞超过目标外的B细胞，从而提高了我们诱导正确的体细胞集的机会 加强免疫期间的超突变。因此，在使用aiMAb进行免疫后，将使用加强剂。 使用专门设计用于接合种系VRC01类BCR(426c核心)的Env进行免疫，然后 通过EVS表达VRC01类抗体的关键立体区块。在这方面，我们强调以下事实： 自从我们第一次提交以来，我们产生了新的信息，表明426c核心引发抗体 绕过保守的N-连接糖基化位点N276上的多糖，这是主要障碍之一 防止种系VRC01类抗体变得广泛中和。我们将测试我们提议的 战略通过迭代的方法和良好的综合实验。我们提供的初步数据支持 我们的总体方法。

ABSTRACT The elicitation of potent and broad HIV-1 neutralizing antibodies (bNAbs) by immunization has been one of the major goals of HIV-1 vaccine research since the beginning of the HIV/AIDS epidemic. During the past decade, significant technical and conceptual advances have enabled the isolation and detailed characterization of a plethora of new bNAbs from HIV-1-infected subjects. The structural characterization of such antibodies, combined with information on their ontogenies, has vastly improved our understanding of how such antibodies are generated during natural infection, leading to new hypotheses regarding how to elicit them by immunization. Our HIVRAD Program grant aims at testing novel reagents and prime-boost immunization schemes to elicit VRC01-class bNAbs, which are among the most broad and potent HIV-1 neutralizing antibodies known and display impressive protective potential in animal studies. However, the development of VRC01-class bNAbs by immunization will necessitate overcoming several obstacles. A successful immunization scheme will likely require, at a minimum, the availability of novel immunogens to initiate and guide the bNAb maturation process, the development of strategies that will minimize the expansion of competing off-target B cells, the development of optimal ‘boost’ Env immunogens to guide the appropriate antibody maturation, and the supply of sustained T helper responses. Here we propose to test concepts, not tested previously, that we have developed to directly address these issues. One new strategy we will evaluate is based on the use of anti-idiotypic monoclonal antibodies (aiMAbs) we generated against germline VRC01- class BCRs. Our preliminary data suggest that these aiMAbs specifically expand naive B cells that express germline VRC01-class B cell receptors (BCRs) and that these cells enter the germinal center (GC) reaction and expand even further upon Env immunization. One obvious advantage is a greater expansion in GC of desired B cells over ‘off target’ B cells, thus improving our chance to induce the correct set of somatic hypermutations during the boost immunizations. Thus, immunizations with aiMAbs will be followed by booster immunizations with an Env specifically designed to engage germline VRC01-class BCRs (426c Core) and then with Envs expressing key steric blocks for VRC01-class antibodies. In this regard we highlight the fact that since our initial submission we generated new information which indicates that the 426c Core elicits antibodies that bypass glycans on the conserved N-linked glycosylation site N276, which are one of the major obstacles preventing germline VRC01-class antibodies from becoming broadly neutralizing. We will test our proposed strategy by an iterative approach with well-integrated experiments. The preliminary data we present support our overall approach.