B cell lineage directed rational vaccine strategies based on CAP256SU Env-Ab coevolution

项目摘要/摘要： 开发有效的艾滋病毒疫苗仍然是一项重大挑战。HIV疫苗的先前策略 旨在诱导保护性T细胞反应、非中和抗体、广谱中和抗体的设计 (BNAbs)，或三者的某种组合，但未能预防感染。这笔赠款旨在促使 通过结合多个V2顶点bNab生殖系前体的启动的新策略，免疫聚焦 促进和分子引导的亲和力成熟。这项研究设计源于一个日益增长的共识，即 一种成功的基于bNab的疫苗的关键要素将是它的能力：i)有效地激活和扩展 罕见的天然bNab编码的B细胞前体；ii)免疫聚焦这些B细胞对规范的、保守的 BNab表位位于HIV env三聚体上，远离靶标表位；以及iii)亲和力-通过以下方式成熟这种反应 一个分子引导的Env-Ab共同进化过程。本申请中提出的研究设计解决了 这三个方面都是bNab诱导的关键。重要的是，我们建议以V2顶端bNab为目标 SuperSite，因为它独特的脆弱性，这使得它可以成为bNAbs的目标，而不是那么体细胞 高度突变和亲和力成熟，无V基因插入或缺失，限制较少 特殊的轻链配对。因此，我们的建议在其他HIV-1疫苗中是独一无二的 针对相对更具挑战性的bNab靶点的计划，如CD4bs、V3-葡聚糖补丁、融合 多肽或MPER。该项目包括三个目标：Aim#1将分离HIV包膜V2-顶端bNAbs CAP256.SU Env Shiv(猿猴免疫缺陷病毒)感染的RMS，鉴定其未突变的共同 祖先(UCA)通过下一代测序进行谱系追踪，并通过Env-Ab共同进化推断 分析CAP256.SU“环境免疫类型”选择的亲和力成熟和中和广度。目标2 将开发与V2顶端bNab Ucas亲和力增强的CAP256 SU三聚体免疫原 体外定向反向疫苗工程，针对多只恒河猴和人V2顶端bNab Ucas。我们 将针对本机配置验证此优化的CAP256.SU GT-Trimer，并将其准备为可溶SOSIP 三聚体和纳米颗粒展示的三聚体作为激活多个稀有的V2-顶端bNab B细胞的启动物质进行测试 远交RMS的前驱基因。目标#3将研究一种基于B细胞谱系的Prime-Boost免疫策略 RMS通过合理设计的Env三聚体蛋白免疫诱导V2-顶端bNab反应。小说 该疫苗接种方案的方面将是激活多个生殖系前体的HIV-1环境SOSIP启动 B细胞；使用MT145KdV5 SOSIP Env(猿猴免疫缺陷病毒Env)的V2顶端免疫聚焦增强 在V2顶端C链表位中保留与HIV-1选择性抗原交叉反应的黑猩猩)，以及 与来自Env-2的亲和力分级的V2顶端抗原相对应的Env SOSIP三聚体的抛光免疫 SHIV.CAP256.SU感染RMS的AB协同进化分析这项研究将是此类研究的第一次，如果 成功地在RMS中诱导bNAbs，将代表基于谱系的疫苗设计的新范式。

PROJECT SUMMARY/ABSTRACT: The development of an effective HIV vaccine remains a major challenge. Previous strategies for HIV vaccine design aimed to elicit protective T cell responses, non-neutralizing antibodies, broadly neutralizing antibodies (bnAbs), or some combination of the three but have failed to protect against infection. This grant aims to elicit bnAbs by a novel strategy that combines priming of multiple V2 apex bnAb germline precursors, immunofocused boosting, and molecularly-guided affinity-maturation. This study design derives from a growing consensus that critical elements to a successful bnAb-based vaccine will be its ability to: i) efficiently activate and expand multiple rare naïve bnAb-encoding B cell precursors; ii) immunofocus these B cell responses to canonical, conserved bnAb epitopes on the HIV Env trimer and away from off-target epitopes; and iii) affinity-mature this response by a process of molecularly-guided Env-Ab co-evolution. The study design proposed in this application addresses each of these three critical aspects of bnAb elicitation. Importantly, we propose to target the V2 apex bnAb supersite because of its unique vulnerabilities, which allow it to be targeted by bnAbs with less somatic hypermutation and affinity maturation, without V-gene insertions or deletions and with less restriction for particular light chain pairings. Our proposal is thus unique among the constellation of other HIV-1 vaccine programs that target relatively more challenging bnAb targets such as the CD4bs, V3-glycan patch, fusion peptide or MPER. The project includes three aims: Aim #1 will isolate HIV envelope V2-apex site bnAbs from CAP256.SU Env SHIV (simian-human immunodeficiency virus)-infected RMs, identify their unmutated common ancestors (UCAs) through lineage-tracing by Next-Gen sequencing, and infer through Env-Ab co-evolution analyses CAP256.SU “Env immunotypes” that select for affinity-maturation and neutralization breadth. Aim #2 will develop CAP256.SU trimer immunogens that exhibit enhanced affinity for V2 apex bnAb UCAs by employing in-vitro directed reverse vaccine engineering that targets multiple rhesus and human V2 apex bnAb UCAs. We will validate this optimized CAP256.SU GT-trimer for native configuration and prepare it as a soluble SOSIP trimer and nanoparticle-displayed trimer for testing as a prime to activate multiple rare V2-apex bnAb B cell precursors in outbred RMs. Aim #3 will investigate a B cell lineage-based prime-boost immunization strategy in RMs to induce V2-apex bnAb responses by rationally engineered Env trimer protein immunizations. Novel aspects of this vaccination regimen will be an HIV-1 Env SOSIP prime that activates multiple germline precursor B cells; a V2 apex immunofocused boost using MT145KdV5 SOSIP Env (a simian immunodeficiency virus Env from chimpanzees that retains selective antigenic cross-reactivity with HIV-1 in V2 apex C-strand epitopes), and “polishing” immunizations with Env SOSIP trimers corresponding to affinity-graded V2 apex antigens from Env- Ab coevolution analyses from SHIV.CAP256.SU infected RMs. This study will be the first of its kind, and if successful in inducing bnAbs in RMs, would represent a new paradigm for lineage-based vaccine design.