Epitope shifting and Antibody Maturation during Rotavirus Infection

轮状病毒感染期间的表位转移和抗体成熟

• 批准号: 8318028
• 负责人: BENJAMIN W SPILLER
• 金额: $ 23.39万
• 依托单位: VANDERBILT UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2011
• 资助国家: 美国
• 起止时间: 2011-08-15 至 2015-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8318028
• 关键词: Address; Adult; Affinity; Antibodies; Antibody Binding Sites; Antibody Formation; Antigens; Attenuated; Binding; Biochemical; Burial; Centers for Disease Control and Prevention (U.S.); Child; Complex; Crystallography; DNA Sequence Rearrangement; Data; Development; Diarrhea; Disease; Dose; Egg White; Epitopes; Family; Frequencies; Generations; Genes; Haptens; Head; Hot Spot; Human; Hydrophobic Surfaces; Immune response; Immune system; Immunity; Immunodominant Epitopes; Immunoglobulin Somatic Hypermutation; Infant; Infection; Lead; Light; Location; Methods; Modeling; Molecular; Molecular Immunology; Monoclonal Antibodies; Muramidase; Mutate; Process; Property; Proteins; Publishing; Reporting; Rotavirus; Rotavirus Infections; Rotavirus Vaccines; Side; Site; Site-Directed Mutagenesis; Somatic Mutation; Structure; Subunit Vaccines; Surface; Surrogate Markers; Testing; Vaccination; Vaccines; Variant; Viral Proteins; Virion; Virus; Work; base; chimeric antibody; improved; interest; mutant; neutralizing antibody; pathogen; progenitor; response

DESCRIPTION (provided by applicant): We will explore and determine the molecular mechanism for epitope shift, a recently recognized feature of affinity maturation in which somatic hypermutation changes the epitope recognized by mature antibodies from that recognized by germline antibodies. Our published work indicates that affinity maturation leads to both affinity and epitope selection changes, both of which can be critical for developing neutralizing antibodies. To date, this has been unappreciated because previous studies of affinity maturation have focused on cases where maturation improves affinity to an essentially identical epitope. This is the case both for protein antigens and haptens, as exemplified by structural and biochemical studies using hen egg white lysozyme and small haptens. In these cases, affinity maturation improves binding to identical epitopes. The anti-lysozyme antibodies are particularly interesting in this light, because they use large (~1,800E2) interfaces with essentially identical interactions where enhanced affinity arises from increased burial of hydrophobic surface at the edge of the interaction surface. These changes are driven by subtle rearrangements of non-hotspot residues. While the edge of the interaction surface changes in the anti- lysozyme antibodies, these changes do not lead to changes in the epitope recognized. In our model, this is because hot-spot residues are germline encoded. Our proposed work will explore changes hypothesized to occur within the antibody combining site and establish the mechanism whereby these changes cause epitope shifting. We will focus anti-rotavirus VP6 antibodies that use the VH1-46 gene segment. VP6 is the immunodominant epitope and VH1-46 is the dominant heavy chain gene segment seen in the antibody response against rotavirus. In general, adults produce neutralizing antibodies to rotavirus, but infants do not. This is not due to germline gene usage, but rather it is to more somatic hypermutation in adults. Rotaviruses are the most important cause of severe diarrhea in infants and young children in both the developed world and the developing world. Attenuated virus vaccines have been introduced, however even when properly administered in a controlled setting, these vaccines appear to reduce infection by only ~61%. Additionally, they offer no protection against emerging strains, and require multiple (2 or 3) doses. Second generation vaccines with improved efficacy are sought, and subunit vaccines are an attractive choice. CDC estimates are that even with vaccination ~500,000 people still die annually from rotavirus infection. Effective development of subunit vaccines is aided by a comprehensive understanding of the mechanisms the human immune system employs to recognize antigens and neutralize pathogens. This application will provide molecular immunology paradigms that may influence the choice of antigens, the use of surrogate markers of protection, and the development of new rotavirus vaccines. We will explore and determine the molecular basis for epitope shift.

描述(申请人提供)：我们将探索和确定表位转换的分子机制，这是最近公认的亲和力成熟的特征，其中体细胞超突变改变了成熟抗体识别的表位，而不是种系抗体识别的表位。我们发表的工作表明，亲和力成熟会导致亲和力和表位选择的变化，这两者对开发中和抗体都是至关重要的。到目前为止，人们还没有意识到这一点，因为以前对亲和力成熟的研究主要集中在成熟可以提高对基本相同表位的亲和力的情况下。蛋白质抗原和半抗原都是如此，使用蛋清溶菌酶和小半抗原进行的结构和生化研究就是例证。在这些情况下，亲和力成熟改善了与相同表位的结合。在这一点上，抗溶菌酶抗体特别有趣，因为它们使用大的(~1,800E2)界面，具有基本相同的相互作用，其中亲和力增强是由于在相互作用表面边缘增加了疏水性表面的埋藏。这些变化是由非热点残基的微妙重排驱动的。虽然抗溶菌酶抗体相互作用表面的边缘发生了变化，但这些变化并不会导致识别表位的变化。在我们的模型中，这是因为热点残基是生殖系编码的。我们提议的工作将探索假设发生在抗体结合位点内的变化，并建立这些变化导致表位移动的机制。我们将重点关注使用VH1-46基因片段的抗轮状病毒VP6抗体。VP6是轮状病毒的免疫优势表位，VH1-46是轮状病毒抗体反应中的优势重链基因片段。一般来说，成年人会产生针对轮状病毒的中和抗体，但婴儿不会。这不是由于生殖系基因的使用，而是因为成年人体内更多的体细胞过度突变。轮状病毒是发达国家和发展中国家婴幼儿严重腹泻的最重要原因。已经引入了减毒病毒疫苗，然而，即使在受控环境下适当地接种，这些疫苗似乎也只减少了~61%的感染。此外，它们对新出现的菌株没有保护作用，需要多次(2或3)剂量。人们正在寻找疗效更好的第二代疫苗，亚单位疫苗是一个有吸引力的选择。CDC估计，即使接种了疫苗，每年仍有约50万人死于轮状病毒感染。对人类免疫系统用于识别抗原和中和病原体的机制的全面了解有助于亚单位疫苗的有效开发。这一应用将提供分子免疫学范式，可能影响抗原的选择、保护的替代标记的使用以及新轮状病毒疫苗的开发。我们将探索和确定表位转换的分子基础。