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

• 批准号: 10540729
• 负责人: Leonidas Stamatatos
• 金额: $ 63.83万
• 依托单位: FRED HUTCHINSON CANCER CENTER
• 依托单位国家: 美国
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-12-06 至 2024-11-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/10540729
• 关键词: Affinity; Alleles; Amino Acids; Animal Experiments; Animal Model; Antibodies; Antibody Affinity; Antibody Formation; Antibody Response; Antigens; B-Cell Activation; 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 Idiotypes; Immunoglobulin Somatic Hypermutation; In Vitro; Infection; Knock-in Mouse; 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; 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

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.

摘要 VRC 01类广泛中和抗体（bNAb）识别CD 4-CD 10内的保守表位。 HIV-1 Env.它们是已知最有效的bNAb之一，可以保护动物免受 实验性S/HIV感染，使其成为通过疫苗接种引发的高度有吸引力的抗体类型。他们 已从多名HIV-1感染受试者中分离出，但均来自相同的VH 1 -2等位基因（*02） 和少量的轻链，所有这些轻链都表达5个氨基酸的CDRL 3。相对于成熟的，完全 突变形式的VRC 01类抗体，其推断的种系形式不识别Env， 中和HIV-1这导致了先前的重组Env免疫原在免疫中无效的假设。 激活表达生殖系VRC 01 B类细胞受体（BCR）的幼稚B细胞，这可能部分解释了 为什么这些免疫原在疫苗研究中没有引起VRC 01样抗体反应。我们报道了 设计结合种系VRC 01类抗体的进化枝C衍生的Env蛋白（426 c核心）， 在体内启动表达相应BCR的幼稚B细胞的扩增，但不足以诱导 这些BCR向其中和形式的成熟。为了引出任何 通过免疫的bNAb是由于存在于保守结构域的聚糖施加的空间限制。 Env的环D中的糖基化位点N276。这些聚糖限制了对生殖细胞识别的表位的接近， VRC 01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 它们“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VRC 01类 因此，bNAbs将取决于我们引导种系VRC 01类抗体沿着进化的能力。 特定的成熟途径来绕过N276聚糖施加的限制。在本项目中，我们建议 使用以前没有测试过的概念和试剂，努力克服这些主要障碍， 通过免疫产生VRC 01类抗体。具体来说，我们建议使用抗独特型 针对种系VRC 01类抗体的单克隆抗体（aiMAb），以特异性地增加 在用种系结合“426 c核心”免疫之前表达VRC 01的B细胞的频率 免疫原，然后用选择VRC 01类B细胞的基于Env的试剂加强免疫 可以绕过N276聚糖的限制。我们的研究将在一个迭代的 在表达VRC 01类BCR的各种动物模型中， 多克隆人BCR库。