Characterization of neutralizing antitoxins and epitopes in Clostridium difficile patients

摘要 艰难梭菌感染（CDI）中的肠道损伤和炎症是发病率增加的原因， 死亡率和经济成本，是由两个大的梭菌毒素介导的：TcdA和TcdB。虽然 针对每种毒素的抗体已被证明与保护有关，但尚不清楚哪种类型的抗体具有保护作用。 抗体和它们的表位负责患者中针对CDI的有效免疫。这个目标 项目是确定CDI中保护性体液免疫应答的特征， 中和TcdA和TcdB表位。假设是针对主要中和抗体的宿主抗体 TcdA和TcdB中的表位赋予针对CDI的保护。为了验证这一假设，我们将首先验证我们的 关于中和抗TcdA/TcdB应答的初步发现， 也与防止复发相关（目标1）;随后我们将描述C。艰难梭菌毒素特异性 克隆水平的B细胞应答，并将这些应答与CDI疾病进展和复发相关联（目的2）;以及 最后，我们将从单个B细胞中克隆中和抗体，以获得一组代表性的人类 针对这两种毒素的保护性单克隆抗体，并表征其结合表位和反应性 产生的各种毒素。difficile地方性和爆发性菌株（Aim 3）。完成 这些特定的目标可以导致抗体生物标志物的发现，这些生物标志物可以预测大多数疾病的结果。 CDI管理中的重大临床问题，包括CDI发生率、严重程度和复发。 保护性抗体的鉴定和表征也可以促进新型被动免疫的开发。 免疫疗法和疫苗方法。

Abstract Intestinal injury and inflammation in Clostridium difficile infection (CDI), an increasing cause of morbidity, mortality and financial cost in the US, is mediated by two large clostridial toxins: TcdA & TcdB. Although antibodies against each toxin have been shown to be associated with protection, it is unclear what types of antibodies and their epitopes are responsible for effective immunity against CDI in patients. The goal of this project is to define the characteristics of a protective humoral immune response in CDI and the major neutralizing TcdA & TcdB epitopes. The hypothesis is that host antibodies directed against major neutralizing epitopes in TcdA & TcdB confer protection against CDI. To test this hypothesis, we will first validate our preliminary finding on neutralizing anti-TcdA/TcdB responses that correlate protection against severe CDI will also correlate protection against recurrence (Aim 1); subsequently we will characterize C. difficile toxin-specific B cell responses at clonal level and correlate these with CDI disease progression and recurrence (Aim 2); and finally we will clone neutralizing antibodies from individual B cells to obtain a representative panel of human protective monoclonal antibodies against the two toxins and characterize their binding epitopes and reactivity to a variety of toxins produced by major C. difficile endemic and outbreak strains (Aim 3). The completion of these specific aims can lead to the discovery of antibody biomarkers that predict outcomes of the most significant clinical issues in CDI management, including CDI occurrence, severity, and recurrence. Identification and characterization of protective antibodies may also facilitate the development of novel passive immunotherapy and vaccine approaches.