High-resolution definition of B cell responses to HIV Env for immunogen design

项目摘要 针对HIV Env的广泛中和抗体（bNAb）的激发是HIV感染的主要途径之一。 HIV-1疫苗开发的挑战。然而，作为一种疫苗成分，HIV-1 Env 迄今为止，大多数临床前和临床研究中的中和广度和效力有限。的 从HIV感染个体中分离第二代bNAb并进行表征 它们在Env上的同源表位，为理解 引发bNAb应答的潜在机制。作为一个功能最强大的 HIV Env的保守和可接近元件，即受体结合位点，即CD 4 结合位点（CD 4 bs），在病毒与受体CD 4的结合中起着至关重要的作用， 在自然感染中作为bNAb应答的易受攻击目标。VRC 01类bNAb，一个子集 从供体45和许多其他HIV感染者中分离出的CD 4 bs bNAbs强烈 支持利用VRC 01类bNAb作为疫苗模板的前提。但目前的 基于Env的免疫原不能够通过以下途径引发有效的VRC 01类bNAb应答： 预防针推断的VRC 01类bNAb种系前体（gVRC 01）通常显示 对原型Env免疫原的亲和力弱或无明显亲和力。因此，免疫原修饰 包括有效激活、选择性扩张和精确引导 CD 4 bs bNAb诱导需要bNAb生殖系前体（生殖系靶向），但满足 成功有限。在上一个资助期间，我们成立了一个基于环境的小组， 具有所需抗原性的设计免疫原，用于引发CD 4 bsbNAb应答。在这 根据建议，我们的目标是通过一个创新计划来扩大我们的努力，该计划包括以下内容 三个互补的具体目标：（1）研究新的免疫原性 bNAb种系BCR敲入小鼠中的免疫原/方案;（2）研究 新免疫原在豚鼠和携带非免疫原OmniMouse 2模型中免疫原性 重排的人抗体基因座;和（3）探索C3/V4中的新中和表位 作为潜在的bNAb应答靶点。我们相信，通过这项研究， (i)有助于彻底了解B细胞对免疫应答的基本方面。 接种疫苗和自然感染后的HIV-1 Env;和（ii）贡献新的免疫原， 新的疫苗靶点和优化的疫苗接种方案，从而提高中和作用 靶向保守的Env元件的应答。

Project Summary The elicitation of broadly neutralizing antibodies (bNAbs) against HIV Env is one of the major challenges of HIV-1 vaccine development. As a vaccine component, HIV-1 Env however elicits limited neutralizing breadth and potency in most pre-clinical and clinical studies to date. The isolation of second generation of bNAbs from HIV-infected individuals, and characterization of their cognate epitopes on Env, offer a tremendous opportunity for understanding the mechanisms underlying the elicitation of bNAb responses. As one of the most functionally conserved and accessible elements of the HIV Env, the receptor binding site, namely CD4 binding site (CD4bs), plays a crucial role for virus engagement with receptor CD4 while serves as a vulnerable target for bNAb response in natural infections. VRC01-class bNAbs, a subset of CD4bs bNAbs isolated from donor 45 and numerous other HIV-infected individuals strongly supports the premise of utilizing VRC01-class bNAbs as vaccine template. However, current Env-based immunogens are not capable of eliciting potent VRC01-class bNAb response via vaccination. The inferred VRC01- class bNAb germline precursors (gVRC01) often display weak or no apparent affinity to prototypical Env immunogens. Thus, immunogen modifications including approaches for efficiently activating, selectively expanding, and precisely shepherding bNAb germline precursors (germline targeting) are needed for CD4bs bNAb elicitation, yet met with limited success. During the last funding period, we established a panel of Env-based designer immunogens with desirable antigenicity for eliciting CD4bs bNAb response. In this proposal, we aim to extend our effort by an innovative program consisting of the following three complementary specific aims: (1) to investigate the immunogenicity of novel immunogens/regimens in bNAb germline BCR knockin mice; (2) to investigate the immunogenicity of novel immunogens in guinea pigs and OmniMouse2 model that carries un- rearranged human antibody loci; and (3) to explore a novel neutralizing epitope in the C3/V4 region of the Env as potential bNAb response target. We believe that through this study we will (i) contribute to the thorough understanding of the basic aspects of the B cell response to the HIV-1 Env following vaccination and natural infection; and (ii) contribute new immunogens, new vaccine target, and optimized vaccination regimens leading to improved neutralizing responses targeting conserved Env elements.