Combining germline-targeting, B cell immunofocusing and Env-Ab co-evolution strategies to induce HIV Envelope V2-apex broadly neutralizing antibodies

项目概要/摘要： 事实证明，开发有效的艾滋病毒疫苗是一项艰巨的挑战。先前针对艾滋病毒的策略 疫苗设计旨在引发保护性 T 细胞反应、非中和抗体、广泛中和 抗体（bnAbs），或三者的某种组合。迄今为止，这三种方法都未能始终如一地 保护非人类灵长类动物 (NHP) 或人类免受感染。这笔赠款旨在通过 首次结合种系靶向、免疫聚焦和分子引导的新颖策略 亲和力成熟。这项研究设计源于日益增长的共识，即成功的关键要素 基于 bnAb 的疫苗将因其能够有效结合并激活稀有的幼稚 B 细胞种系前体的能力 bnAb；免疫聚焦这些 B 细胞对 HIV Env 三聚体上典型、保守的 bnAb 表位的反应 并远离脱靶菌株特异性表位或三聚体碱基表位；并成熟或“完善”这个 bnAb 谱系 通过分子引导的 Env-Ab 协同进化过程做出反应。本申请中提出的研究设计 满足这三个基本要求中的每一个，因为它的目的是引出针对高度保守的 bnAbs HIV-1 V2-顶点位点。主要研究人员（Andrabi 和 Shaw）组建了一支才华横溢的合作团队 研究团队在科学发现、生物工程和分子工具开发方面拥有良好的记录， 包括 V2-apex bnAbs (Burton) 的发现、种系靶向 V2 apex 免疫原的开发 (Andrabi)，磷酸丝氨酸连接的明矾纳米粒子抗原展示的生物工程(Irvine)，V2-的发现 apex 免疫聚焦黑猩猩免疫缺陷病毒 (Hahn)，创建 CRISPRCas9 敲入 小鼠 (Batista)、下一代“设计”SHIV 的开发 (Shaw) 以及临床前-临床转化 （戴伊）。该项目有四个目标： 目标 #1 将 HIV 包膜 V2-apex 靶向 bnAbs 从 SHIV 中分离出来 感染恒河猴，识别它们的 UCA，并生成表达 UCA 的敲入小鼠模型 疫苗评估。目标 #2 将设计新型 V2-apex 种系靶向和免疫聚焦的 SOSIP Env 三聚体 免疫原并通过哺乳动物展示饱和诱变和结构引导设计将它们呈现为 可溶性蛋白质或明矾纳米颗粒可增强 B 细胞反应。目标 #3 将优化种系 - V2-apex bnAb UCA 表达 KI 小鼠和远交小鼠的靶向和 B 细胞免疫聚焦增强策略 RM，并将在 SOSIP Env 引发的和 SHIV 感染的 RM 中识别出可以驱动的 Env“免疫型” 中和广度。目标 #4 将首先在 KI 小鼠中进行设计和测试，然后在 RM 中进行关键的临床前试验， 全 SOSIP Env 疫苗接种方案，旨在在大多数人中引发、增强和亲和力成熟 bnAb 反应 的动物。如果成功，这将是第一个在体内持续引发 bnAb 的疫苗方案的例子 一种近交动物模型，它将代表 HIV-1 疫苗科学的一个重要滩头阵地 我们的翻译合作伙伴可以快速将其转化为人体测试。

PROJECT SUMMARY/ABSTRACT: The development of an effective HIV vaccine has proven to be a daunting 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. All three approaches have thus far failed to consistently protect nonhuman primates (NHPs) or humans from infection. This grant aims to elicit bnAbs by means of a novel strategy that combines – for the first time – germline-targeting, immunofocusing and molecularly guided affinity maturation. This study design evolves from a growing consensus that critical elements to a successful bnAb-based vaccine will be its ability to efficiently bind and activate rare naïve B cell germline precursors of bnAbs; to immunofocus these B cell responses to canonical, conserved bnAb epitopes on the HIV Env trimer and away from off-target strain specific or trimer base epitopes; and to mature or “polish” this bnAb lineage response by a process of molecularly guided Env-Ab coevolution. The study design proposed in this application addresses each of these three essential requirements as it aims to elicit bnAbs targeting the highly conserved HIV-1 V2-apex site. The principal investigators (Andrabi and Shaw) have assembled a talented collaborating research team with a strong track record of scientific discovery, bioengineering and molecular tool development, including the discovery of V2-apex bnAbs (Burton), development of germline targeted V2 apex immunogens (Andrabi), bioengineering of phosphoserine-linked alum nanoparticle antigen displays (Irvine), discovery of V2- apex immunofocusing chimpanzee simian immunodeficiency viruses (Hahn), creation of CRISPRCas9 knock-in mice (Batista), development of next-generation “designer” SHIVs (Shaw) and preclinical-clinical translation (Dey). The project consists of four aims: Aim #1 will isolate HIV envelope V2-apex targeted bnAbs from SHIV infected rhesus macaques, identify their UCA’s, and generate UCA-expressing knock-in mouse models for vaccine evaluation. Aim #2 will design novel V2-apex germline-targeted and immunofocused SOSIP Env trimer immunogens and by mammalian display saturation mutagenesis and structure-guided design present them as soluble proteins or alum-based nanoparticles for enhanced B cell responses. Aim #3 will optimize germline- targeting and B cell immunofocusing boost strategies in V2-apex bnAb UCA-expressing KI-mice and outbred RMs, and will identify in SOSIP Env primed and SHIV infected RMs, Env “immunotypes” that can drive neutralization breadth. Aim #4 will design and test, first in KI mice and then in a pivotal preclinical trial in RMs, an all-SOSIP Env vaccination regimen designed to prime, boost and affinity-mature bnAb responses in a majority of animals. If successful, this would be the first example of a vaccine regimen that consistently elicits bnAbs in an outbred animal model, and it would represent an important beachhead in HIV-1 vaccine science, one that could be transitioned rapidly by our translational partner into human testing.