Interplay between antibody affinity maturation and HIV evolution in a single host

单个宿主中抗体亲和力成熟与 HIV 进化之间的相互作用

• 批准号: 9012685
• 负责人: Daniela Fera
• 金额: $ 5.13万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-12-22 至 2016-10-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/9012685
• 关键词: Affect; Affinity; Antibodies; Antibody Affinity; Antibody Binding Sites; Antibody Response; Antigens; B-Lymphocytes; Binding; Binding Sites; Carbohydrates; Cell Separation; Characteristics; Cloning; Collaborations; Complex; Coupled; Crystallization; Data; Development; Dissociation; Epitopes; Evolution; Goals; HIV; HIV Envelope Protein gp120; HIV vaccine; Hemagglutinin; Human; Immune; Immune response; Immune system; Immunoglobulin Variable Region; Immunologic Deficiency Syndromes; Individual; Infection; Influenza; Institutes; Interferometry; Light; Measurement; Mutate; Mutation; Pathway interactions; Peptides; Polysaccharides; Population; Positioning Attribute; Process; Property; Race; Research; Research Proposals; Sampling; Siblings; Staging; Structure; Surface; Technology; Testing; Time; Trees; Vaccination; Vaccines; Variant; Viral; Viral Antibodies; Virion; Virus; Virus Diseases; Work; arm; design; glycosylation; improved; influenzavirus; member; molecular dynamics; mutant; neutralizing antibody; pathogen; progenitor; public health relevance; research study; response; vaccine development; virus envelope

 DESCRIPTION (provided by applicant): Rapidly evolving pathogens, such as the human immunodeficiency virus (HIV), escape immune defenses provided by most vaccine-induced antibodies. Proposed strategies to elicit broadly neutralizing antibodies (bnAbs) require a deeper understanding of evolution of the immune response to vaccination or infection. In HIV infected individuals, viruses and B-cells evolve together, creating a virus-antibody "arms race". The objective of this proposal is to analyze the arms race in donors such as CH505 and CH0694, who have developed antibodies of significant breadth, which would be informative for immunogen design. Donor CH505 produced a lineage of antibodies, called CH103, which interact with the gp120 CD4 binding site. Analysis of crystal structures of progenitor (UCA) and intermediate Fabs, along with binding measurements to various HIV envelope gp120s, indicated that there was a shift in the relative orientation of the variable light-chain (VL) and heavy-chain (VH) domains during evolution in this lineage to relieve unfavorable contacts with gp120. Because a VH-VL shift would change the way the antibodies interact with gp120, a deeper analysis of VH-VL interface changes and changes in affinity for gp120 will be performed. Crystal structures will be determined of gp120 in complex with the UCA or intermediate Fab I3.2, whose VH-VL orientations differ from that of the mature bnAb, already solved in complex with gp120. Molecular dynamics (MD) simulations will also be done, as a collaboration, of free Fabs and Fab/gp120 complexes, and coupled with additional binding experiments. Antibodies from the DH235 lineage, from the same donor, triggered virus escape mutations that improved binding to CH103 lineage antibodies and therefore could have accelerated affinity maturation in the CH103 lineage. Crystal structures of Fabs of DH235 lineage members will be determined to understand how the DH235 antibodies, which have limited neutralization breadth, differ from CH103 bnAbs despite overlapping epitopes, and to reconstruct the interplay among the two lineages and virus. In addition to rapid mutation, HIV also uses heavy glycosylation to evade the immune system. BnAbs that bind to glycans have been isolated, suggesting that viral carbohydrates can serve as vaccine targets. An early bnAb, called DH175, was identified from donor CH0694 and shown to be "PGT-like". While many PGT bnAbs recognize N332 glycosylation, their actual epitopes differ in the glycans and gp120 peptides they recognize. To understand antibody affinity maturation and virus evolution in this lineage, crystal structures of the DH175/gp120 complex and of the free Fabs of precursor antibodies will be determined. Hypotheses concerning stages of affinity maturation deduced from the crystal structures will be tested by introducing mutations into the Fabs and/or gp120 envelope and determining affinities and neutralization properties. MD simulations will also be performed, as a collaboration, if appropriate. These data will identify mechanism(s) that confer broadly neutralizing characteristics on glycan-dependent antibodies.

 描述（由适用提供）：迅速发展的病原体，例如人类免疫缺陷病毒（HIV），大多数疫苗诱导的抗体提供的逃生免疫消除剂。提出的引起广泛中和抗体（BNAB）的策略需要更深入地了解对疫苗或感染的免疫响应的进化。在艾滋病毒感染的个体中，病毒和B细胞共同发展，形成病毒抗体“武器竞赛”。该提案的目的是分析CH505和CH0694等捐助者的武器竞赛，他们开发了大量广度的抗体，这对于免疫原设计提供了信息。 供体CH505产生了一种称为CH103的抗体谱系，该抗体与GP120 CD4结合位点相互作用。分析祖细胞（UCA）和中间晶圆厂的晶体结构，以及与各种HIV Invelope GP120s的结合测量结果，表明，在这种谱系中，可变光链（VL）（VL）（VL）（VL）（VL）（VH）的相对方向发生了变化，以挽救与GP120相关的这种谱系。由于VH-VL偏移会改变抗体与GP120相互作用的方式，因此将对VH-VL接口变化进行更深入的分析，以及对GP120的亲和力的变化。晶体结构将与UCA或中间Fab I3.2复合物中的GP120确定，其VH-VL方向与已与GP120复合物求解的VH-VL方向不同。作为一种合作，将进行分子动力学（MD）模拟，并将其与其他结合实验相结合。来自同一供体的DH235谱系的抗体触发了病毒逃生突变，从而改善了与CH103谱系抗体结合的结合，因此可以加速CH103谱系中的亲和力成熟。将确定DH235谱系成员Fabs的晶体结构，以了解中和宽度有限的DH235抗体如何与CH103 BNAB拼命重叠的表位不同，并重建两个谱系之间的相互作用。 除了快速突变外，HIV还使用重糖基化来逃避免疫系统。已经分离出与聚糖结合的BNAB，这表明病毒碳水化合物可以用作疫苗靶标。从供体CH0694中鉴定出一种称为DH175的早期BNAB，并显示为“ PGT样”。尽管许多PGT BNAB识别N332糖基化，但它们的实际表位在它们识别的聚糖和GP120肽中不同。为了了解该谱系中的抗体亲和力成熟和病毒进化，将确定DH175/GP120复合物和前体抗体的游离晶圆厂的晶体结构。关于从晶体结构中推论的亲和力成熟阶段的假设将通过将突变引入Fabs和/或GP120包膜中，并确定亲密关系和神经化特性来测试。如果适当，也将进行MD模拟，作为协作。这些数据将确定会议在聚糖依赖性抗体上广泛中和特征的机制。