Vanderbilt Antibody and Antigen Discovery for Clostridioides difficile Vaccines

整体项目总结 艰难梭状芽胞杆菌Vandy-CDV疫苗的Vanderbilt抗体及抗原发现 艰难梭状芽胞杆菌是一种形成孢子的厌氧细菌，是医院感染的主要原因。 在美国获得性胃肠道感染。社区发病率的上升- 健康成人获得性艰难梭菌感染(CDI)与抗生素使用量的增加有关 以及新菌株的出现。CDI症状和病理由两个大的 同源毒素，TcdA和TcdB，因此这些毒素是有吸引力的目标 预防和治疗策略。虽然努力集中在使用类毒素来治疗 免疫接种在减轻症状方面显示出了希望，类毒素方法已经 没有导致临床试验中CDI的发生率降低。有几个机会可以 改进现有的疫苗策略。首先，大规模的基因组研究表明，TcdB是 经历快速进化变化的；可以使用保守的毒素表位的鉴定 引导免疫反应产生广泛的中和反应。第二, 细菌或孢子表面保守抗原的鉴定 可以作为免疫原，允许宿主激发粘膜免疫反应，防止 细菌定植。预计纳入粘膜免疫途径将进一步 提高疫苗效力和耐用性。Vandy-CDV计划的首要目标是 识别毒素亚基和新的细胞表面抗原，当它们结合在一起时，会促进耐久性 对艰难梭菌感染和症状的保护。在众多创新优势中， 方法包括使用人类CDI患者样本作为资源，以了解 在自然感染中，抗原可促进免疫球蛋白、免疫球蛋白A和sIgA反应。该方法还包括 采用功能强大的单B细胞分选和测序方法。辨别配对对象的能力 单个记忆B细胞结合毒素和/或细菌的重链和轻链序列 允许产生独特的抗体，然后将其用作表位映射的工具 和新的抗原发现。该方法的第三个亮点涉及使用新创建的 艰难梭菌转座子文库将用于在体内鉴定新的抗原 疫苗接种/挑战实验。其他创新包括以结构为导向的方法 确定有效的中和表位并系统评估肠道淋巴细胞如何 免疫反应因免疫途径不同而异。疫苗效力和粘膜相关因素 保护性将在定植、感染和复发的临床前模型中进行评估。在 五年后，我们希望有临床前的数据来开发一种新的抗原 鸡尾酒和免疫策略进入人体安全性和有效性试验。

OVERALL PROJECT SUMMARY Vanderbilt Antibody and Antigen Discovery for Clostridioides difficile Vaccines VANDy-CdV Clostridioides difficile is a spore-forming anaerobic bacterium that is the leading cause of hospital- acquired gastrointestinal infection in the United States. The rising incidence of community- acquired C. difficile infection (CDI) in otherwise healthy adults is linked to increased antibiotic use and the emergence of new strains. CDI symptoms and pathology are mediated by two large homologous toxins, TcdA and TcdB, and therefore the toxins represent attractive targets for prevention and therapeutic strategies. While efforts centered around the use of toxoids for immunization have shown promise in reducing the severity of symptoms, the toxoid approach has not resulted in a decreased incidence of CDI in clinical trials. There are several opportunities to improve upon existing vaccine strategies. First, large scale genomic studies show that TcdB is undergoing rapid evolutionary change; the identification of conserved toxin epitopes can be used to direct the immune response toward the production of broadly neutralizing responses. Second, the identification of conserved antigens on the surface of the vegetative bacteria or spores that can serve as immunogens will allow the host to elicit mucosal immune responses that prevent bacterial colonization. The inclusion of mucosal immunization routes is expected to further enhance vaccine efficacy and durability. The overarching goal of the VANDy-CdV program is to identify toxin subunits and novel cell surface antigens that, when combined, promote durable protection against C. difficile infection and symptoms. Among many innovative strengths, the approach includes the use of human CDI patient samples as a resource for understanding what antigens promote IgG, IgA, and sIgA responses in natural infection. The approach also includes the use of powerful single B cell sorting and sequencing methods. The ability to identify paired heavy and light chain sequences from individual memory B cells binding toxins and/or bacteria allows for the production of unique antibodies that can then be used as tools for epitope mapping and novel antigen discovery. A third highlight of the approach involves the use of a newly created C. difficile transposon library which will be used to identify novel antigens in an in vivo vaccination/challenge experiment. Other innovations include a structure-guided approach to identifying potent, neutralizing epitopes and a systematic evaluation of how intestinal lymphocyte responses vary with routes of immunization. Vaccine efficacy and the mucosal correlates of protection will be evaluated in pre-clinical models of colonization, infection, and recurrence. At the end of five years, we expect to have the pre-clinical data needed to advance a novel antigen cocktail and immunization strategy forward into human safety and efficacy trials.