Development of prime-boost immunization schemes to elicit VRC01-class bNAbs in polyclonal human BCR backgrounds

开发初免-加强免疫方案以在多克隆人 BCR 背景中引发 VRC01 类 bNAb

基本信息

批准号：
10593446
负责人：
Leonidas Stamatatos
金额：
$ 30.76万
依托单位：
FRED HUTCHINSON CANCER CENTER
依托单位国家：
美国
项目类别：
财政年份：
2018
资助国家：
美国
起止时间：
2018-12-06 至 2023-11-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/10593446
关键词：
Affinity Alleles Amino Acids Animal Model Animals Antibodies Antibody Affinity Antibody Formation Antibody Response Antigens B-Cell Antigen Receptor B-Lymphocyte Epitopes B-Lymphocytes Binding Binding Sites Bypass Carbohydrates Collaborations Development Elements Engineering Epitopes Evolution Frequencies Generations Genes Goals Grant Growth HIV HIV Infections HIV-1 Human Immunization Immunoglobulin Somatic Hypermutation In Vitro Infection Knock-in Knock-in Mouse Lead Learning Light Link Methodology Monoclonal Antibodies Mus Mutate Pathway interactions Polysaccharides Positioning Attribute Process Proteins Reagent Recombinants Reporting Scheme Secondary Immunization Series Site Site-Directed Mutagenesis Somatic Mutation Specificity Testing Transgenic Mice Vaccination Virus adoptive B cell transfer base design env Gene Products experimental study glycosylation improved in vivo mouse model neutralizing antibody novel prevent simian human immunodeficiency virus success vaccination strategy vaccine trial

项目摘要

ABSTRACT VRC01-class broadly neutralizing antibodies (bNAbs) recognize a conserved epitope within the CD4- binding site of HIV-1 Env. They are among the most potent bNAbs known and protect animals from experimental S/HIV infection, making them a highly attractive type of antibody to elicit by vaccination. They have been isolated from multiple HIV-1-infected subjects, but are all derived from the same VH1-2 allele (*02) and a small number of light chains, all of which express a 5 amino-acid CDRL3. In contrast to the mature, fully mutated forms of VRC01-class antibodies, their inferred germline forms do not recognize Env and do not neutralize HIV-1. This led to the hypothesis that previous recombinant Env immunogens were ineffective in activating naïve B cells expressing germline VRC01-class B cell receptors (BCRs), which may, in part, explain why such immunogens have not elicited VRC01-like antibody responses in vaccine studies. We reported on the design of a clade C-derived Env protein (426c Core) that binds germline VRC01-class antibodies and initiates the expansion of naïve B cells expressing the corresponding BCRs in vivo, but is insufficient to induce the maturation of these BCRs towards their neutralizing forms. A major hurdle to overcome in order to elicit any bNAbs through immunization is due to steric restrictions imposed by glycans present at the conserved glycosylation site N276 in Loop D of Env. These glycans limit access to the epitope recognized by germline VRC01-class antibodies, but as the antibodies undergo somatic hypermutation and affinity-based selection they ‘learn’ how to bypass this steric block. The success of our immunization strategies to elicit VRC01-class bNAbs will therefore depend on our ability to guide the evolution of germline VRC01-class antibodies along particular maturation pathways to bypass the N276 glycan-imposed restrictions. In this Project we propose to use concepts and reagents, not tested previously, in an effort to overcome these major obstacles preventing the generation of VRC01-class antibodies by immunization. Specifically, we propose to use anti-idiotypic monoclonal antibodies (aiMAbs) against the germline VRC01-class antibodies to specifically increase the frequency of VRC01-expressing B cells prior to immunization with the germline-binding’ 426c Core immunogen, followed by booster immunizations with Env-based reagents that select for VRC01-class B cells that can bypass the restrictions imposed by the N276 glycans. Our studies will be performed in an iterative fashion in diverse animal models that express VRC01-class BCRs, including mice engineered to express a polyclonal human BCR repertoire.

抽象的 VRC01 类广泛中和抗体 (bNAb) 可识别 CD4- 内的保守表位 HIV-1 Env 的结合位点它们是已知最有效的 bNAb，可保护动物免受感染。实验性 S/HIV 感染，使它们成为通过疫苗接种引发的极具吸引力的抗体类型。已从多个 HIV-1 感染受试者中分离出来，但均源自相同的 VH1-2 等位基因 (*02) 和少量轻链，与成熟的、完全表达的CDRL3相比，它们全部表达5个氨基酸。 VRC01 类抗体的突变形式，其推断的种系形式不识别 Env，并且不中和 HIV-1，这导致了先前的重组 Env 免疫原对 HIV-1 无效的假设。激活表达种系 VRC01 类 B 细胞受体 (BCR) 的幼稚 B 细胞，这可能部分解释我们报道了为什么此类免疫原在疫苗研究中没有引起类似 VRC01 的抗体反应。结合种系 VRC01 类抗体的进化枝 C 衍生的 Env 蛋白（426c 核心）的设计启动体内表达相应 BCR 的初始 B 细胞的扩增，但不足以诱导这些 BCR 向中和形式的成熟是引发任何问题需要克服的主要障碍。通过免疫接种产生的 bNAb 是由于保守位点上存在的聚糖所施加的空间限制造成的。 Env 环 D 中的糖基化位点 N276 这些聚糖限制了对种系识别表位的访问。 VRC01 类抗体，但由于抗体经历体细胞超突变和基于亲和力的选择他们“学习”如何绕过这个空间阻滞我们的免疫策略成功地引发了 VRC01 级。因此，bNAb 将取决于我们指导种系 VRC01 类抗体进化的能力在这个项目中，我们建议绕过 N276 聚糖施加的限制的特定成熟途径。使用之前未测试过的概念和试剂，努力克服这些阻碍的主要障碍具体来说，我们建议通过免疫产生VRC01类抗体。针对种系 VRC01 类抗体的单克隆抗体 (aiMAbs) 特异性增加使用种系结合的 426c 核心进行免疫之前表达 VRC01 的 B 细胞的频率免疫原，然后使用基于 Env 的试剂进行加强免疫，选择 VRC01 类 B 细胞我们的研究将迭代进行，可以绕过 N276 聚糖的限制。在表达 VRC01 类 BCR 的多种动物模型中流行，包括被设计为表达 VRC01 类 BCR 的小鼠多克隆人类 BCR 库。