Development of Vaccines against Clostridium difficile Infection

艰难梭菌感染疫苗的研制

• 批准号: 7903007
• 负责人: Hanping Feng
• 金额: $ 66.39万
• 依托单位: TUFTS UNIVERSITY BOSTON
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-04-15 至 2015-03-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7903007
• 关键词: Accounting; Acute; Address; Adjuvant; Affinity; Age; Amino Acids; Anorexia; Antibiotic Resistance; Antibiotic Therapy; Antibiotics; Antibodies; Antibody Formation; Antigens; Bacillus megaterium; Biological Assay; Body Weight decreased; Cell Culture Techniques; Characteristics; Chemicals; Chimera organism; Chimeric Proteins; Chronic; Chronic Disease; Clostridium difficile; Data; Development; Diarrhea; Disease; Dose; Encapsulated; Endotoxins; Enteral; Epithelial; Epithelium; Epitopes; Europe; Exotoxins; Family; Feces; Fluids and Secretions; Formalin; Gnotobiotic; Goals; Health; Hospitalization; Human; Immunity; Immunization; Immunoglobulin Fragments; Immunoglobulin G; Incidence; Infection; Inflammation; Inflammatory; Inflammatory Bowel Diseases; Inflammatory disease of the intestine; Intervention; Intoxication; Laboratories; Laboratory mice; Length; Measures; Mediating; Methods; Modeling; Monitor; Morbidity - disease rate; Mucosal Immunity; Mucous Membrane; Mus; Nature; Necrosis; North America; Oral; Outcome; Patients; Placebos; Point Mutation; Polymers; Positioning Attribute; Prevention; Probiotics; Proteins; Pseudomembranous Colitis; Recombinant Proteins; Recombinants; Recurrence; Regimen; Relapse; Request for Applications; Research; Route; Safety; Secondary Immunization; Secretory Immunoglobulin A; Serum; Severities; Staging; Symptoms; System; Testing; Time; Toxic effect; Toxin; Toxoids; Transmembrane Domain; Vaccination; Vaccines; Virulence; abstracting; aluminum sulfate; base; comparative efficacy; cytotoxicity; design; holotoxins; molecular mass; mortality; neutralizing antibody; pathogen; preclinical evaluation; prevent; protective efficacy; receptor binding; research clinical testing; research study; response; rho GTP-Binding Proteins; treatment strategy; vaccine candidate; vaccine development

DESCRIPTION (provided by applicant): This proposal is in response to RFA-AI-09-016 requesting applications to develop vaccines for selected pathogens including Clostridium difficile, the cause of pseudomembranous colitis, which accounts for a quarter of all cases of antibiotic-associated diarrhea. With the recent emergence of hypervirulent strains, the incidence of C. difficile infection (CDI) has increased significantly in both North America and Europe, causing lengthy hospitalization, substantial morbidity and mortality. CDI is thought to be mainly mediated by exotoxins TcdA and TcdB, which glucosylate low molecular mass GTPases of the Rho family, leading to massive fluid secretion, acute inflammation, and necrosis of the colonic mucosa. Protection against CDI was shown to be mediated through systemic and mucosal antibodies against the 2 key toxins, although other virulence attributes are known to exist which may also contribute to the manifestation of CDI. The goal of this proposal is to design a vaccine that targets both TcdA and TcdB, with a view to elicit strong systemic and mucosal immunity to prevent CDI, reduce the severity, or eliminate an ongoing chronic disease. We propose to exploit the recently expressed atoxic C. difficile holotoxin proteins in an endotoxin-free Bacillus megaterium system. Two immunogens will be evaluated: a mixture of atoxic full-length C. difficile toxin A and B generated by point mutations (designated as aTxAB), and a chimera protein containing full-length TcdB but with its receptor binding domain replaced with that of TcdA (designated as cTxAB). cTxAB has a small deletion (97 amino acids) in transmembrane domain rendering it non-toxic. Preliminary studies showed that atoxic TcdB vaccination induced antibody responses against a wide-spectrum of epitopes and potent protective immunity superior to toxoid; cTxAB immunization induced antibody and protective responses against both TcdA and TcdB. In this project, we will first evaluate the ability of these atoxic recombinant proteins to induce protective antibody responses following parenteral immunization followed by challenge with wild type toxins (Aim 1). This will be followed by evaluating several regimens of mucosal immunizations (oral, intranasal and sublingual) designed to induce protection against systemic and mucosal challenges with wild type toxins (Aim 2). We will test the protective efficacy of the various immunization regimens developed in Aims 1 and 2 in the recently described mouse acute infection model (Aim 3a), and the most efficient immunization method resulting from the mouse infection studies will undergo preclinical evaluation in the chronic piglet model of CDI developed in this laboratory (Aim 3b). Because at this early stage the nature of the candidate vaccine is unknown, nor is the adjuvant required, we are not in a position to form a suitable partnership. Abstract Narrative: Clostridium difficile-associated diarrhea and enteric inflammatory diseases are caused primarily by two secretory toxins. This project will use recombinant atoxic holotoxins produced in this lab as a basis for a vaccine to elicit strong systemic and mucosal immunity to prevent C. difficile infection, reduce the severity, or eliminate an ongoing chronic disease.

描述（由申请人提供）： 该提案是为了响应 RFA-AI-09-016 要求申请开发针对特定病原体的疫苗，其中包括艰难梭菌，它是伪膜性结肠炎的病因，占所有抗生素相关性腹泻病例的四分之一。随着最近高毒力菌株的出现，艰难梭菌感染（CDI）的发病率在北美和欧洲显着增加，导致住院时间长、发病率和死亡率高。 CDI被认为主要由外毒素TcdA和TcdB介导，它们使Rho家族的低分子GTP酶进行葡萄糖基化，导致大量液体分泌、急性炎症和结肠粘膜坏死。对 CDI 的保护作用被证明是通过针对两种关键毒素的全身和粘膜抗体介导的，尽管已知存在其他毒力属性，这也可能导致 CDI 的表现。该提案的目标是设计一种同时针对 TcdA 和 TcdB 的疫苗，以期引发强大的全身和粘膜免疫，以预防 CDI、减轻严重程度或消除正在进行的慢性疾病。我们建议在无内毒素巨大芽孢杆菌系统中利用最近表达的无毒艰难梭菌全毒素蛋白。将评估两种免疫原：由点突变产生的无毒全长艰难梭菌毒素 A 和 B 的混合物（称为 aTxAB），以及包含全长 TcdB 但其受体结合域被 TcdA 取代的嵌合蛋白（指定为 cTxAB）。 cTxAB 在跨膜结构域中有一个小缺失（97 个氨基酸），使其无毒。初步研究表明，无毒 TcdB 疫苗接种可诱导针对广谱表位的抗体反应，并产生优于类毒素的强效保护性免疫； cTxAB 免疫诱导针对 TcdA 和 TcdB 的抗体和保护性反应。在这个项目中，我们将首先评估这些无毒重组蛋白在肠外免疫后诱导保护性抗体反应的能力，然后用野生型毒素攻击（目标 1）。随后将评估几种粘膜免疫方案（口服、鼻内和舌下），旨在诱导针对野生型毒素的全身和粘膜挑战的保护（目标 2）。我们将在最近描述的小鼠急性感染模型（目标3a）中测试目标1和目标2中开发的各种免疫方案的保护效果，并且由小鼠感染研究得出的最有效的免疫方法将在慢性仔猪中进行临床前评估本实验室开发的 CDI 模型（目标 3b）。由于在早期阶段候选疫苗的性质尚不清楚，也不需要佐剂，因此我们无法形成合适的合作伙伴关系。 摘要叙述：艰难梭菌相关的腹泻和肠道炎症性疾病主要由两种分泌毒素引起。该项目将使用本实验室生产的重组无毒全毒素作为疫苗的基础，以引发强大的全身和粘膜免疫，以预防艰难梭菌感染、减轻严重程度或消除正在进行的慢性疾病。