Serogroup 19 capsule maleability leading to vaccine failure

血清群 19 胶囊的雄性能力导致疫苗失败

• 批准号: 10723991
• 负责人: Moon H. Nahm
• 金额: $ 18.56万
• 依托单位: UNIVERSITY OF ALABAMA AT BIRMINGHAM
• 依托单位国家: 美国
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-08-17 至 2025-07-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10723991
• 关键词: Affect; Alleles; Amino Acid Substitution; Amino Acids; Anabolism; Antibodies; Antibody Response; Appearance; Bacteria; Bacterial Capsules; Binding; Biochemical; Bioinformatics; Biological; Carbohydrates; Cell surface; Cessation of life; Clinical; Conjugate Vaccines; Cytoplasm; Databases; Disease; Effectiveness; Foundations; Future; Genetic; Genetic Polymorphism; Genomics; Goals; Human; Immune response; Immunity; Immunization; Immunize; Immunologics; In Vitro; Individual; Infection; Integration Host Factors; Investigation; Length; Link; Lipopolysaccharides; Mediating; Medical; Membrane; Methods; Modeling; Molecular; Mutagenesis; Mutation; Outcome; Pathway interactions; Persons; Play; Polymerase; Polysaccharides; Population; Property; Proteins; Reporting; Research; Role; Serotyping; Site; Specificity; Streptococcus pneumoniae; Structure; Surface; Testing; Trisaccharides; Vaccinee; Vaccines; Variant; Virulence; breakthrough infection; burden of illness; capsule; clinically relevant; design; experience; fitness; gene function; genetic variant; improved; microbial; novel; pathogen; pathogenic bacteria; preservation; success; tool; trait; vaccine evaluation; vaccine failure; vaccine-induced immunity

Streptococcus pneumoniae (the “pneumococcus”) is an important human commensal pathogen. A key determinant of pneumococcal fitness and virulence is its ability to produce a protective polysaccharide (PS) capsule which can take the form of >100 biochemically distinct “serotypes”. Pneumococcal capsule PS conjugate vaccines (PCVs) induce protective antibodies that mediate opsonophagocytic killing (OPK) of pneumococci and have effectively reduced the global burden of disease caused by serotypes included in vaccines. Despite this success, immunized people occasionally experience breakthrough infections by PCV serotypes, and the cause for these cases of “vaccine failure” remains unclear. Investigation of vaccine failure has largely focused on host factors and ineffective antibody response, while microbiological aspects have gone largely unaddressed. Furthermore, closely-related serotypes 19A and 19F are the serotypes most commonly implicated in vaccine failure cases, but few studies have evaluated their role in this phenomenon. Appreciating the breadth of capsule malleability and its impact on clinical outcomes, we are examining a potential link between serotype 19A/19F capsule variants, evasion of anti-capsule immune responses, and vaccine failure. Preliminary analyses identified multiple candidate mechanisms through which polymorphisms in the 19A/19F capsule polymerase Wzy can mediate considerable capsule variability while preserving most capsule features. We also found a strain that was serotyped as “19F” by conventional methods, but in fact produces a novel capsule PS structure, herein called 19x. Thus, the full diversity of 19A/19F-like capsule types is yet to be defined. As even small changes in capsule structure can abrogate cross-protective immunity, it is possible that some variants, which are indistinguishable from 19A/19F pneumococci in conventional serotyping methods, can nonetheless evade OPK by anti-19A/19F capsule antibodies in vaccinated individuals and, thus, spur the vaccine failure attributed to these serotypes. In this R21 proposal, we will perform directed mutagenesis to test the impact of Wzy polymorphisms on 19A/19F capsules structure and test the effect of these putative capsule changes on evading anti-capsule antibody-mediated OPK in vitro (Aim 1). We will also structurally/genetically/antigenically characterize the novel 19x capsule type and perform bioinformatics analysis of expansive genomic databases with the goal of identifying other putative capsule variants found among immunized populations (Aim 2). Importantly, tools and concepts developed here will fuel future investigation of the impact capsule PS malleability has in additional pneumococcal serotypes and other medically important bacterial pathogens that employ similar pathways for glycan synthesis. Independent of glycobiological advances, elucidation of the molecular basis of 19A/19F Wzy enzymatic specificity would immediately improve the precision of the molecular typing strategies.

肺炎链球菌（“肺炎球菌”）是一种重要的人类共生病原体。 肺炎球菌适应性和毒力的决定因素是其产生保护性多糖 (PS) 的能力 肺炎球菌胶囊 PS 可以采用 >100 种生化不同的“血清型”形式。 结合疫苗（PCV）诱导介导调理吞噬杀伤（OPK）的保护性抗体 肺炎球菌，并有效减少了由肺炎球菌血清型引起的全球疾病负担 尽管取得了这一成功，但免疫人群偶尔会出现 PCV 的突破性感染。 血清型，以及这些“疫苗失败”病例的原因仍不清楚。 主要关注宿主因素和无效的抗体反应，而微生物方面已经消失 此外，密切相关的血清型 19A 和 19F 是最常见的血清型。 与疫苗失败案例有关，但很少有研究评估它们在这种现象中的作用。 认识到胶囊延展性的广度及其对临床结果的影响，我们正在研究 血清型 19A/19F 荚膜变体、逃避抗荚膜免疫反应之间的潜在联系 初步分析确定了多态性导致疫苗失败的多种候选机制。 19A/19F 胶囊聚合酶 Wzy 可以介导相当大的胶囊变异性，同时保留大多数 我们还发现了一种按常规方法血清分型为“19F”的菌株，但实际上。 产生了一种新颖的胶囊 PS 结构，本文称为 19x，因此，具有 19A/19F 样胶囊类型的全部多样性。 尚待定义，因为即使胶囊结构发生微小变化也可能消除交叉保护。 免疫，可能存在一些与 19A/19F 肺炎球菌无法区分的变种 传统的血清分型方法，仍然可以通过抗 19A/19F 荚膜抗体来逃避 OPK 疫苗接种个体，因此，刺激了归因于这些血清型的疫苗失败。 在这个 R21 提案中，我们将进行定向诱变来测试 Wzy 多态性对 19A/19F胶囊结构并测试这些假定的胶囊变化对逃避反胶囊的影响 抗体介导的 OPK 体外（目标 1）我们还将对其进行结构/遗传/抗原表征。 新颖的 19x 胶囊类型并对广泛的基因组数据库进行生物信息学分析，目的是 识别在免疫群体中发现的其他假定的胶囊变异（目标 2）。 这里开发的概念将推动未来对冲击胶囊 PS 延展性的研究 肺炎球菌血清型和其他医学上重要的细菌病原体采用相似的途径 独立于糖生物学进展，阐明 19A/19F Wzy 的分子基础 酶特异性将立即提高分子分型策略的精确度。