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（由申请人提供）：快速进化的病原体，如人类免疫缺陷病毒（HIV），逃避大多数疫苗诱导抗体提供的免疫防御。引发广泛中和抗体（bnAb）的拟议策略需要更深入地了解疫苗接种或感染的免疫应答的演变。在HIV感染者中，病毒和B细胞一起进化，创造了病毒抗体“军备竞赛”。该提案的目的是分析诸如CH 505和CH 0694的供体中的军备竞赛，这些供体已经开发出具有显著广度的抗体，这将为免疫原设计提供信息。 供体CH 505产生了称为CH 103的抗体谱系，其与gp 120 CD 4结合位点相互作用。前体（UCA）和中间Fab的晶体结构分析，沿着与各种HIV包膜gp 120的结合测量，表明在该谱系的进化过程中，可变轻链（VL）和重链（VH）结构域的相对取向发生了变化，以减轻与gp 120的不利接触。由于VH-VL移位将改变抗体与gp 120相互作用的方式，因此将对VH-VL界面变化和对gp 120的亲和力变化进行更深入的分析。将确定gp 120与UCA或中间体Fab I3.2复合物的晶体结构，其VH-VL取向不同于成熟bnAb的VH-VL取向，成熟bnAb已经在与gp 120的复合物中溶解。分子动力学（MD）模拟也将完成，作为合作，游离Fab和Fab/gp 120复合物，并与额外的结合实验相结合。来自同一供体的来自DH 235谱系的抗体触发了病毒逃逸突变，其改善了与CH 103谱系抗体的结合，因此可以加速CH 103谱系中的亲和力成熟。将确定DH 235谱系成员的Fab的晶体结构，以理解具有有限中和宽度的DH 235抗体如何不同于CH 103 bnAb，尽管存在重叠表位，并重建两个谱系和病毒之间的相互作用。 除了快速突变，HIV还利用重糖基化来逃避免疫系统。与聚糖结合的BnAb已被分离出来，这表明病毒碳水化合物可以作为疫苗靶点。从供体CH 0694中鉴定出一种称为DH 175的早期bnAb，并显示为“PGT样”。虽然许多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gp 120肽中不同。为了理解该谱系中的抗体亲和力成熟和病毒进化，将确定DH 175/gp 120复合物和前体抗体的游离Fab的晶体结构。将通过将突变引入Fab和/或gp 120包膜并确定亲和力和中和性质来测试关于从晶体结构推导的亲和力成熟阶段的假设。如果适当，还将进行MD模拟，作为合作。这些数据将确定赋予聚糖依赖性抗体广泛中和特征的机制。