Development of a novel antibody therapy for clostridium difficile infection

描述（由申请人提供）：艰难梭菌是医院和社区获得性胃肠道感染的常见原因，患者在接受各种抗菌药物治疗其他感染后可能会发生这种感染。C.艰难梭菌感染可引起更严重的疾病，并且可能对目前的标准形式的治疗是难治的。近年来，一种毒性更强的C.已经出现了艰难梭菌，在一些患者中引起严重疾病。对C.艰难梭菌感染虽然尚未完全了解，但涉及由生物体产生的两种毒素A毒素（TcdA）和B毒素（TcdB）对肠上皮的作用。有非常好的证据表明，抗TcdA和TcdB的抗体在人类和C.艰难性结肠炎本研究的目的是开发一种以抗体为基础的免疫治疗C。艰难梭菌感染的克隆人单克隆抗体（mAb）从个人与C。difficile，并使用仓鼠感染模型确定这些抗体是否可以预防疾病。这些抗体将通过使用噬菌体展示系统克隆患者的抗体在体外产生，该研究的共同研究者唐纳德·西格尔博士是该技术的先驱之一。毒素特异性抗体将在体外产生，并将测试这些抗体保护动物免受C.艰难性结肠炎在过去的15年中，该技术的使用已经产生了对大量人自身抗原和同种异体抗原以及人感染因子具有特异性的人单克隆抗体。因此，噬菌体展示技术是用于以利用人免疫系统产生高亲和力、抗原选择性、对疾病相关表位具有不同特异性的抗体的大库的能力的方式产生完全人蛋白质的理想方法。鉴于本提案中将开发的抗体数量众多，该策略将提供足够的表征试剂，并允许我们选择最佳抗体（或抗体组合）作为治疗用途的先导化合物。 公共卫生相关性：艰难梭菌是医疗机构中抗生素相关性腹泻的最常见原因之一，因为越来越多地被认为是社区获得性感染。 医院获得性C.艰难梭菌疾病导致显著更高的住院费用和住院时间，并且在美国估计超过10亿美元。因此，C.艰难梭菌病是相当大的公共卫生问题。

DESCRIPTION (provided by applicant): Clostridium difficile is a common cause of both hospital- and community acquired gastrointestinal infection that may occur after patients have been treated for other infections with a variety of antimicrobial agents. While mostly causing antibiotic-associated diarrhea, C. difficile infection may cause more severe disease and may be refractory to current standard forms of therapy. In recent years, a more virulent strain of C. difficile has emerged that has caused serious disease in some patients. The pathogenesis of C. difficile infection, while not completely understood, involves the action of two toxins, toxin-A (TcdA) and toxin-B (TcdB), produced by the organism, on the gut epithelium. There is very good evidence showing that antibodies against TcdA and TcdB have protective effects against disease in humans and in animal models of C. difficile colitis. The purpose of the current study is to develop an antibody-based immunotherapy for C. difficile infection by cloning human monoclonal antibodies (mAbs) from individuals with C. difficile and determine whether these antibodies can protect against disease using a hamster model of infection. The antibodies will be produced in vitro by cloning patients' antibodies using a phage display system, a technique for which Dr. Donald Siegel, Co- Investigator of the study, is among the pioneers. Toxin specific antibodies will be produced in vitro and will be tested for the ability of these antibodies to protect animals from developing C. difficile colitis. Use of this technology over the past 15 years has produced human monoclonal antibodies with specificities against a large number of human auto- and alloantigens, and human infectious agents. Thus, phage display technology is an ideal approach for producing completely human proteins in a way that exploits the human immune system's ability to generate large repertoires of high affinity, antigen selected, antibodies with varying specificities for disease- associated epitopes. Given the multitude of antibodies that will be developed in this proposal, the strategy will provide enough reagents for characterization and allow us to choose optimal antibodies (or combinations of antibodies) as lead compounds for therapeutic use. PUBLIC HEALTH RELEVANCE: C difficile is one of the most common causes of antibiotic associated diarrhea in healthcare settings as is being increasingly recognized as a community acquired infection. Patients with nosocomially acquired C. difficile disease incur significantly higher hospital costs and length of stay and has been estimated to exceed 1 billion dollars in the US. Thus, C. difficile disease is of considerable public health concern.