Evaluating anti-idiotypic antibodies as novel vaccine candidates against HIV-1

项目摘要/摘要 与HIV-1包膜糖蛋白(Env)结合的广谱中和抗体(BNAbs)有望 成为有效的艾滋病毒-1疫苗引起的免疫反应的重要组成部分。然而，努力实现 用重组Env疫苗诱导bNAb尚未获得成功。VRC01类抗体 是从感染者身上分离出来的最广泛和最有效的bNAb之一，他们的 启发性将是疫苗的理想目标。已经从多个捐赠者身上分离出VRC01类抗体， 并且它们都以几乎相同的方式与Env相互作用；它们来自相同的抗体重链基因， VH1-2*02；并且在轻链上具有异常短的第三互补决定区域(CDRL3)。 在感染过程中，VRC01类抗体的抗体发生了许多突变。 使他们能够识别和中和各种HIV-1病毒分离株的基因。利用序列同源性，人们可以 预测产生每个VRC01类的原始B细胞上的B细胞受体(BCR)的序列 抗体。我们小组和其他人之前的工作已经证明，这些推断的胚系版本 VRC01类抗体不能识别不同的重组env。因此，传统的环境免疫原是 可能在结合和激活原始B细胞方面无效，这可能会产生VRC01类抗体。 VRC01类抗体的结构相似性和共同的遗传学导致了这样的假设 专为结合VRC01类前体B细胞而设计的免疫原至少可以启动 VRC01级抗体生产工艺。事实上，我们和其他人已经设计了基于环境的免疫原 在体内外均能激活表达VRC01类前体BCRs的B细胞。然而，这些 免疫原还呈现非靶标的、潜在的免疫优势表位，最终可能会挫败 竞争性生发中心反应中VRC01类抗体的发展。 作为环境免疫原的替代品，我们已经生产和分离了抗独特型抗体， 对VRC01类前体BCRs的抗原结合部位具有高度特异性。重要的是，因为他们是 它们不是由Env衍生的，缺乏其他生殖系靶向免疫原存在的靶外表位。我们的 最重要的假设是，如果用作疫苗原剂，抗独特型抗体可以选择性地寻找和 扩增稀有的VRC01类B细胞，这样扩张池将比其他B细胞具有选择性优势 在生殖系靶向Env的推动下，对非靶标表位做出反应。这一假设将得到检验。 作为HIVRAD应用程序的一部分，在转基因小鼠模型中，与Stamatatos博士和 努森茨韦格。这个项目的重点是评估这些新的免疫原寻找稀有物质的能力。 人PBMC和小鼠表达不同人源性VRC01类前体B细胞 Bcr谱系，并设计多价aiMAb衍生物以提高免疫原性。

Project Summary/Abstract Broadly neutralizing antibodies (bNAbs) that bind to the HIV-1 Envelope glycoprotein (Env) are expected to be an important component of the immune response elicited by an effective HIV-1 vaccine. However, efforts to elicit bNAbs through vaccination with recombinant Env have not yet been successful. VRC01-class antibodies are among the broadest and most potent bNAbs that have been isolated from infected individuals, and their elicitation would be an ideal goal of a vaccine. VRC01-class antibodies have been isolated from multiple donors, and they all interact with Env in a nearly identical manner; are derived from the same antibody heavy chain gene, VH1-2*02; and have an unusually short third complimentary determining region (CDRL3) on the light chain. During the course of infection, VRC01-class antibodies acquired a number of mutations in their antibody genes that allow them recognize and neutralize diverse HIV-1 viral isolates. Using sequence homology, one can predict the sequence of the B-cell receptor (BCR) on the naive B cell that gave rise to each VRC01-class antibody. Previous work from our group and others has demonstrated that these inferred-germline versions of VRC01-class antibodies fail to recognize diverse recombinant Envs. Thus, conventional Env immunogens are likely ineffective at binding to and activating naive B cells that can give rise to VRC01-class antibodies. The structural similarity and shared genetics of VRC01-class antibodies have led to the proposal that immunogens designed to specifically to engage VRC01-class precursor B cells could, at the very least, start the process of VRC01-class antibody production. Indeed we, and others, have designed Env-based immunogens that can activate B cells expressing VRC01-class precursor BCRs in vitro and in vivo. However, these immunogens also present off-target, potentially immunodominant epitopes that could ultimately frustrate the development of VRC01-class antibodies in competitive germinal center reactions. As an alternative to Env-derived immunogens, we have produced and isolated anti-idiotypic antibodies that are highly specific for the antigen binding site of VRC01-class precursor BCRs. Importantly, because they are non-Env derived, they lack the off-target epitopes present on other germline-targeting immunogens. Our overarching hypothesis is that if used as a vaccine prime, anti-idiotypic antibodies can selectively seek out and expand rare VRC01-class B cells, such that the expanded pool will have a selective advantage over other B cells that respond to off-target epitopes following a boost with germline-targeting Env. This hypothesis will be tested in transgenic mouse models as part of this HIVRAD application, in collaboration with Drs. Stamatatos and Nussenzweig. The focus of this project is to evaluate the ability of these novel immunogens to seek out rare VRC01-class precursor B cells from human PBMC samples and from mice expressing a diverse human-derived BCR repertoire, and to engineer multivalent aiMAb derivatives to improve immunogenicity.