HIV-1 Q23.17 Env: Engineering a novel immunogen to elicit broadly neutralizing antibodies

项目摘要 在人类中，由HIV-1引起的中和抗体与病毒Env以独特的模式共同进化，在某些情况下， 案件涉及面广。我们发现，原代HIV-1 Env在猴-人表达时， 免疫缺陷病毒（SHIV）在22只恒河猴（RM）中，引起Env-Ab协同进化的模式 与人类的惊人相似（Science 371：eabd 2638，2021）。这包括保守的免疫遗传学， 表位识别和精确Env-氨基酸取代、插入和 删除导致病毒持续存在。一种恒河猴抗体的结构，能够中和49%的 208-应变面板，揭示了类似于人bNAb PGT 145和PCT 64的V2-顶点识别模式。我们 随后将这项研究扩展到包括150个感染SHIV的RM，这些SHIV携带15种不同原发性 HIV-1 Envs;这些动物中有24只（16%）产生了靶向保守的V2顶端、V3聚糖、CD 4 bs或CD 4 b的bNAb。 融合肽表位。V2顶点是RM中靶向的最常见的bNAb表位。我们的结论是 RM中的Env-Ab协同进化概括了人类bNAb的发育特征，并可用于指导和 加速人类HIV-1免疫原的设计。从这些临床前数据中，我们鉴定了HIV-1 Q23.17 Env 作为最一致地引发V2顶点bNAb的免疫原。在这里，我们建议阐明Env-Ab HIV-1 Q23.17 Env选择性启动、增强和亲和力成熟V2顶点的共同进化途径 bNAb应答，并将这些发现转化为全SOSIP Env三聚体疫苗方案， 生殖系靶向Q23.17 Env初免，然后用谱系设计的Q23.17 Env“免疫型”加强 能够亲和成熟B细胞以获得宽度。具体目标是：（一）破译的分子途径， 在SHIV.Q23.17感染的RM中Env-Ab共同进化，导致V2顶端bNAb的发展，包括 推断的种系bNAb前体和谱系中间体以及相应Env的鉴定 与它们结合免疫型;（ii）使用哺乳动物展示饱和诱变产生Q23.17 Env 对多种恒河猴生殖系V2顶端bNA B B细胞前体表现出增强的结合亲和力的变体， 将这些Env工程化为纳米颗粒递送的SOSIP三聚体;（iii）测试种系- 靶向和谱系设计的Q23.17 Env SOSIP三聚体在V2 apex bNAb UCA敲入小鼠和远系杂交小鼠中的表达 并将最有希望的组合推进到RM的概念验证临床前疫苗试验;以及 (iv)在28个RM中进行适当把握度的临床前疫苗试验，以检验逆转- 工程化的、B谱系设计的Q23.17 SOSIP Env三聚体可以引发、加强和亲和成熟V2顶端bNA B b 在RM中的应答达到上级于常规SOSIP Env免疫原并且保护RM的程度 异源病毒攻击。这些研究的意义可能是深远的：如果我们能证明 在RM中使用种系靶向的、谱系设计的Q23.17 Env SOSIP一致诱导bNAb， 代表了HIV-1疫苗研究的一个新的滩头阵地，可以迅速转化为人体临床试验。

PROJECT SUMMARY In humans, neutralizing antibodies elicited by HIV-1 coevolve with viral Envs in distinctive patterns, in some cases acquiring substantial breadth. We found that primary HIV-1 Envs, when expressed by simian-human immunodeficiency viruses (SHIVs) in 22 rhesus macaques (RMs), elicited patterns of Env-Ab coevolution strikingly similar to those in humans (Science 371:eabd2638, 2021). This included conserved immunogenetic, structural and chemical solutions to epitope recognition and precise Env-amino acid substitutions, insertions and deletions leading to virus persistence. The structure of one rhesus antibody, capable of neutralizing 49% of a 208-strain panel, revealed a V2-apex mode of recognition like that of human bNAbs PGT145 and PCT64. We subsequently expanded this study to include 150 RMs infected by SHIVs bearing any of 15 different primary HIV-1 Envs; 24 (16%) of these animals developed bNAbs targeting conserved V2 apex, V3 glycan, CD4bs or fusion peptide epitopes. The V2 apex was the most common bNAb epitope targeted in RMs. We concluded that Env-Ab coevolution in RMs recapitulates developmental features of human bNAbs and may serve to guide and accelerate HIV-1 immunogen design for humans. From these preclinical data, we identified HIV-1 Q23.17 Env as the immunogen that most consistently elicited V2 apex bNAbs. Here, we propose to elucidate the Env-Ab coevolutionary pathways by which HIV-1 Q23.17 Env selectively primes, boosts and affinity-matures V2 apex bNAb responses and to translate these findings into an all-SOSIP Env trimer vaccine regimen consisting of a germline-targeted Q23.17 Env prime followed by boosts with lineage-designed Q23.17 Env “imunotypes” capable of affinity-maturing B cells to achieve breadth. Specific aims are: (i) to decipher molecular pathways of Env-Ab coevolution in SHIV.Q23.17 infected RMs that lead to the development of V2 apex bNAbs, including the identification of inferred germline bNAb precursors and lineage intermediates and corresponding Env immunotypes that bind to them; (ii) to use mammalian display saturation mutagenesis to generate Q23.17 Env variants that exhibit enhanced binding affinity to multiple rhesus germline V2 apex bNAb B cell precursors and to engineer these Envs as nanoparticle-delivered SOSIP trimers; (iii) to test the immunogenicity of germline- targeted and lineage-designed Q23.17 Env SOSIP trimers in V2 apex bNAb UCA knockin mice and outbred RMs and to advance the most promising combinations to a proof-of-concept preclinical vaccine trial in RMs; and (iv) to conduct an appropriately powered preclinical vaccine trial in 28 RMs to test the hypothesis that reverse- engineered, B lineage-designed Q23.17 SOSIP Env trimers can prime, boost and affinity mature V2 apex bNAb responses in RMs to an extent that is superior to conventional SOSIP Env immunogens and that protects RMs from heterologous virus challenge. The significance of these studies could be far-reaching: if we can demonstrate consistent induction of bNAbs using germline-targeted, lineage-designed Q23.17 Env SOSIPs in RMs, it would represent a new beachhead for HIV-1 vaccine research that could be translated rapidly into human clinical trials.