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

肺炎链球菌是一种主要的传染性病原体，可引起肺炎、菌血症、脑膜炎、急性 中耳炎，每年全球有近一百万人死亡。S.肺炎可以在 鼻咽部无症状，这有助于病原体传播，因为肺炎球菌携带通常 在活动性感染之前感染在高风险人群中发生的频率增加， 糖尿病、哮喘、慢性阻塞性肺病、心血管疾病和艾滋病。几 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。 研究，包括目前疫苗的血清型覆盖率有限，对某些疫苗的疫苗效力有限， 包括血清型，定植和非疫苗血清型感染的发生率增加， 在非疫苗血清型中广泛存在药物和多药抗生素耐药性。本R 01提案将 通过定义介导血清型宽度的结构决定因素来解决这些局限性， 预防和治疗肺炎球菌感染的广泛反应性人单克隆抗体的保护功效。的 这一建议的科学前提是，针对保守的肺炎球菌抗原的mAb具有广泛的反应性， 可以作为肺炎球菌疾病管理的优先或替代疗法。该提案将重点 肺炎球菌抗原的mAb是高度保守的，并且是肺炎球菌感染过程中B细胞的靶点。 殖民和感染。我们的工作将通过产生新的治疗选择来推动该领域的发展。 预防和治疗不同血清型的肺炎球菌感染，包括包囊和 非包囊血清型，并通过鉴定肺炎球菌表面蛋白的保护性表位。我们 创新的假设是靶向保守的肺炎球菌表面蛋白的人单克隆抗体将表现出 相当大血清型宽度，可以治疗肺炎球菌感染，且mAb的保护效力和血清型 宽度与表位特异性相关。我们的数据将为肺炎球菌蛋白质提供新的发现 疫苗领域。目的1：研究靶向保守蛋白的人源单克隆抗体的血清型宽度和保护效力 将在原发性和继发性（流感病毒感染后）模型中测定抗原 肺炎球菌感染在目的2中，我们将定义介导人免疫球蛋白的保护功效的表位。 使用X射线晶体学和cryo-EM的mAb，这将是该领域的关键， 蛋白质为基础的肺炎球菌疫苗，因为我们已经表明，在我们的初步数据， 肺炎球菌蛋白影响mAb的宽度和保护效力。在目标3中，我们将在体外进行深入研究， 和体内机制研究，以评估mAb功能，包括调理吞噬和凝集活性， 以及抑制细菌生长、粘附、侵入和生物膜形成。我们还将评估具体的 对mAb介导的细菌清除重要的免疫途径。总的来说，我们的工作既实际 和概念上的创新，并将挑战目前的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.