Epitope and mechanistic correlates of broadly protective human antibodies for pneumococcal infection

肺炎链球菌是一种主要的感染性病原体，可引起肺炎、菌血症、脑膜炎、急性肺炎。 全世界每年有近一百万人死于中耳炎。肺炎链球菌可携带于 无症状的鼻咽，这有助于病原体的传播，因为肺炎球菌携带通常 先于活动性感染。感染在高危人群中发生的频率增加，如个人 糖尿病、哮喘、慢性阻塞性肺疾病、心血管疾病和艾滋病毒。几个 疫苗目前用于预防肺炎球菌感染；然而，有几个因素需要进一步 研究，包括目前疫苗的血清型覆盖范围有限，疫苗对某些疫苗的效力有限- 包括血清型、定殖率增加和感染非疫苗血清型，以及 在非疫苗血清型中广泛存在的药物和多药耐药性。此R01建议书将 通过定义调节血清型广度的结构决定因素和 预防和治疗肺炎球菌感染的广活性人源单抗的保护作用。这个 这一提议的科学前提是针对具有广泛反应性的保守肺炎球菌抗原的单抗 可作为肺炎球菌疾病管理的优先或辅助治疗。这项提案将把重点放在 肺炎链球菌高度保守的B细胞靶抗原单抗的研究 殖民和感染。我们的工作将通过产生新的治疗方案来推动这一领域的发展 预防和治疗不同血清型的肺炎球菌感染，包括包裹型和 通过识别肺炎球菌表面蛋白的保护性表位。我们的 创新的假设是，针对保守的肺炎球菌表面蛋白的人mAbs将展示 相当大的血清型广度，可以治疗肺炎球菌感染，而单抗的保护效果和血清型 广度与表位特异性相关。我们的数据将为肺炎球菌蛋白提供新的发现 疫苗领域。在目标1中，针对保守蛋白的人源单抗的血清型广度和保护效果 抗原将在原发模型和继发模型中确定(在流感病毒感染后) 肺炎球菌感染。在目标2中，我们将定义调节人类保护功效的表位。 单抗使用X射线结晶学和冷冻-EM，这将是该领域的关键，通过告知发展 就像我们在初步数据中显示的那样，基于蛋白质的肺炎球菌疫苗的表位 肺炎球菌蛋白影响单抗的广度和保护效果。在目标3中，我们将在体外进行深入的 以及体内评估单抗功能的机制研究，包括吞噬细胞和凝集活性， 以及抑制细菌生长、黏附、入侵和生物膜形成。我们还将评估具体的 单抗介导细菌清除的重要免疫途径。总体而言，我们的工作实际上是 并在概念上具有创新性，并将挑战目前肺炎球菌感染的治疗模式。

Streptococcus pneumoniae is a leading infectious pathogen, causing pneumonia, bacteremia, meningitis, acute otitis media, and nearly one million deaths worldwide each year. S. pneumoniae can be carried in the nasopharynx asymptomatically, which contributes to pathogen spread, as pneumococcal carriage often precedes active infection. Infections occur with increased frequency in high-risk populations, such as individuals with diabetes, asthma, chronic obstructive pulmonary disease, cardiovascular disease, and HIV. Several vaccines are currently in use to prevent pneumococcal infection; however, several factors warrant further research, including limited serotype coverage of current vaccines, limited vaccine efficacy against some vaccine- included serotypes, increased incidence of colonization and infection with non-vaccine serotypes, and widespread drug and multidrug antibiotic resistance among non-vaccine serotypes. This R01 proposal will address these limitations by defining the structural determinants mediating the serotype breadth and protective efficacy of broadly-reactive human mAbs that prevent and treat pneumococcal infection. The scientific premise of this proposal is that mAbs to conserved pneumococcal antigens that are broadly reactive could serve as priority or adjunctive therapies for pneumococcal disease management. This proposal will focus on mAbs to pneumococcal antigens that are highly conserved and are targets of B cells during pneumococcal colonization and infection. Our work will advance the field by generating new therapeutic options for the prevention and treatment of pneumococcal infection for diverse serotypes, including encapsulated and nonencapsulated serotypes, and by identifying protective epitopes on pneumococcal surface proteins. Our innovative hypothesis is that human mAbs targeting conserved pneumococcal surface proteins will exhibit substantial serotype breadth, can treat pneumococcal infection, and that mAb protective efficacy and serotype breadth is correlated to epitope specificity. Our data will provide new findings for the pneumococcal protein vaccine field. In Aim 1, the serotype breadth and protective efficacy of human mAbs targeting conserved protein antigens will be determined in models of both primary and secondary (following influenza virus infection) pneumococcal infection. In Aim 2, we will define the epitopes mediating the protective efficacy of the human mAbs using X-ray crystallography and cryo-EM, which will be critical to the field by informing the development of protein-based pneumococcal vaccines, as we have shown in our preliminary data that the epitope on pneumococcal proteins impacts mAb breadth and protective efficacy. In Aim 3, we will conduct in depth in vitro and in vivo mechanistic studies to assess mAb functions, including opsonophagocytic and agglutination activity, and inhibition of bacterial growth, adhesion, invasion, and biofilm formation. We will also assess the specific immunological pathways important for mAb-mediated bacterial clearance. Overall, our work is both practically and conceptually innovative, and will challenge current treatment paradigms for pneumococcal infection.