Germline-Specific Immunogens for the Induction of Neutralizing Antibodies to HIV-

用于诱导 HIV 中和抗体的种系特异性免疫原

• 批准号: 8501370
• 负责人: Robert G. Whalen
• 金额: $ 55.15万
• 依托单位: ALTRAVAX, INC.
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8501370
• 关键词: AIDS/HIV problem; Affinity; Antibodies; Antibody Binding Sites; Antibody Formation; Antigens; B-Lymphocytes; Binding; Binding Sites; Biological Assay; Cause of Death; Cells; Complementarity Determining Regions; Coupled; DNA Sequence; Directed Molecular Evolution; Disease; Epidemic; Epitopes; Family; Genes; Genetic Recombination; Genomics; Goals; HIV; HIV Envelope Protein gp120; HIV vaccine; HIV-1; Human; Immune system; Immunization; Immunoglobulins; In Vitro; Individual; Infection; Infection prevention; Influenza; Lead; Libraries; Life; Macaca; Measures; Modeling; Monkeys; Monoclonal Antibodies; Mutate; Mutation; Pathway interactions; Pattern; Production; Protein Binding; Proteins; Reagent; Research Proposals; Specificity; Structure; Technology; Testing; Vaccine Research; Vaccines; Variant; Virus; Work; base; candidate identification; deep sequencing; design; env Gene Products; env Glycoproteins; functional genomics; human monoclonal antibodies; immunogenicity; innovation; neutralizing antibody; neutralizing monoclonal antibodies; pathogen; prevent; response; screening; success; vaccine candidate

DESCRIPTION (provided by applicant): Vaccines can slow the spread of the HIV/AIDS epidemic, and the identification of immunogens that induce neutralizing antibodies remains an important goal of HIV vaccine research. An increasing number of broadly neutralizing human monoclonal antibodies (mAbs) have been isolated from infected individuals who show remarkably broad and potent neutralizing responses. Coupled with past studies, these results support the idea that the human immune system can generate rare but potent protective antibodies to the virus. Much work, including our own, has focused on identifying forms of the HIV-1 envelope glycoprotein (Env) that bind to broadly neutralizing antibodies. In contrast to approaches that optimize Env for binding to these highly affinity-matured antibodies, we now propose to identify Env variants that can bind to the germline form of the broadly neutralizing antibodies as a more productive approach to immunization. While structural studies of antibody-antigen interactions have informed antigen design, the corresponding germline antibody sequences rarely show any binding to the HIV-1 Env. As a result, detailed information is not readily available for the rational design of germline-binding Env. We propose therefore to use a directed molecular evolution approach to identify germline-specific immunogens. Such immunogens could more effectively stimulate naive B cells. The broadly neutralizing VRC01 mAb is well suited to this approach, notably because the CDRH3 domain is less important for the neutralization activity compared to most of the other broadly neutralizing mAbs. This minimizes one of the constraints in predicting the structure of the germline VRC01 precursor. We will create a number of VRC01-like mAbs based on macaque germline sequences that are increasing reverted to the germline sequence and use these as reagents to screen libraries of Env variants created by in vitro homologous DNA recombination. We will immunize macaques with these germline-specific variants and analyze, using massively parallel DNA sequencing technologies, the ability of these Env-based immunogens to stimulate affinity maturation of the specific germline for which they were selected. Based on the results of an initial immunization study, we will identify additional immunogens that stimulate partially affinity-matured antibodies along a particular path to form a mature neutralizing antibody. The germline-specific and the additional immunogens will be used to immunize macaques over a 10-month period. Analysis of the pattern of mutation in the antibody genes will indicate whether it is possible to direct antibody maturation along a specific pathway. Even if we do not succeed in eliciting VRC01-like activity, the results of this study will lead to a greater understanding of the initial response tothe immunogen and to what extent can it be manipulated and controlled. This proposal represents an innovative approach to the identification of candidate immunogens for HIV-1 vaccines. It has general applicability to other pathogens for which protective (or broadly protective) mAbs have been identified (e.g. RSV or influenza) but where induction of those specificities has proven problematic.

描述（申请人提供）：疫苗可以减缓艾滋病毒/艾滋病流行的传播，识别诱导中和抗体的免疫原仍然是艾滋病毒疫苗研究的一个重要目标。从受感染个体中分离出越来越多的广泛中和的人单克隆抗体 (mAb)，这些抗体表现出非常广泛和有效的中和反应。结合过去的研究，这些结果支持了这样的观点，即人类免疫系统可以产生罕见但有效的病毒保护性抗体。许多工作，包括我们自己的工作，都集中在识别与广泛中和抗体结合的 HIV-1 包膜糖蛋白 (Env) 的形式。与优化 Env 以与这些高度亲和力成熟的抗体结合的方法相比，我们现在建议鉴定可以与广泛中和抗体的种系形式结合的 Env 变体，作为更有效的免疫方法。虽然抗体-抗原相互作用的结构研究为抗原设计提供了信息，但相应的种系抗体序列很少显示出与 HIV-1 Env 的任何结合。因此，尚无法获得用于合理设计种系结合环境的详细信息。因此，我们建议使用定向分子进化方法来鉴定种系特异性免疫原。这种免疫原可以更有效地刺激初始B细胞。广泛中和 VRC01 mAb 非常适合这种方法，特别是因为与大多数其他广泛中和 mAb 相比，CDRH3 结构域对于中和活性不太重要。这最大限度地减少了预测种系 VRC01 前体结构的限制之一。我们将基于猕猴种系序列创建许多类似 VRC01 的 mAb，这些序列逐渐恢复为种系序列，并使用这些试剂来筛选通过体外同源 DNA 重组创建的 Env 变体文库。我们将用这些种系特异性变体对猕猴进行免疫，并使用大规模并行 DNA 测序技术分析这些基于 Env 的免疫原刺激其被选择的特定种系亲和力成熟的能力。根据初始免疫研究的结果，我们将确定其他免疫原，这些免疫原可刺激部分亲和力成熟的抗体沿着特定路径形成成熟的中和抗体。种系特异性免疫原和额外的免疫原将用于在 10 个月的时间内对猕猴进行免疫。对抗体基因突变模式的分析将表明是否有可能沿着特定途径引导抗体成熟。即使我们没有成功引发 VRC01 样活性，这项研究的结果也将导致人们更好地了解对免疫原的初始反应以及它可以在多大程度上被操纵和控制。该提案代表了一种识别 HIV-1 疫苗候选免疫原的创新方法。它普遍适用于已识别出保护性（或广泛保护性）mAb 的其他病原体（例如 RSV 或流感），但这些特异性的诱导已被证明存在问题。