Combination Clostridium Difficile Toxin and Adhesin Vaccine

艰难梭菌毒素和粘附素联合疫苗

• 批准号: 8501352
• 负责人: DAVID D HO
• 金额: $ 34.95万
• 依托单位: AARON DIAMOND AIDS RESEARCH CENTER
• 依托单位国家: 美国
• 财政年份: 2012
• 资助国家: 美国
• 起止时间: 2012-07-01 至 2016-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8501352
• 关键词: Active Immunization; Address; Adherence; Adhesions; Adjuvant; Age; Aging; Animal Model; Antibiotics; Antibodies; Antibody Formation; Antigens; Bacillus (bacterium); Bacteria; Bacterial Adhesins; Bacterial Infections; Binding; Boston; Chimeric Proteins; Clinical; Clinical Data; Clostridium difficile; Colitis; Combined Vaccines; Comorbidity; Development; Diarrhea; Disease; Disease Progression; Elderly; Enteral; Environmental Pollution; Epithelial Cells; Evaluation; Exhibits; Family; Flagella; Flagellin; Hamsters; Hand; Heating; Hospitalization; Hospitals; Human; Hygiene; Immune response; Immunity; Immunization; Immunoglobulin G; In Vitro; Incidence; Infection; Infection prevention; Injury; Intestines; Laboratories; Ligands; Measures; Mediating; Mesocricetus auratus; Modeling; Mus; New York; Organism; Outcome; Passive Immunization; Patient Isolation; Patients; Pattern recognition receptor; Play; Population; Prevention; Preventive; Production; Proteins; Receptor Signaling; Recombinant Fusion Proteins; Recombinants; Recurrence; Recurrent disease; Regimen; Reporting; Reproduction spores; Risk; Role; Route; Sampling; Serum; Surface; Symptoms; Testing; Toll-Like Receptor 5; Toll-like receptors; Toxin; United States; Vaccinated; Vaccination; Vaccines; Virulence Factors; Virus; adaptive immunity; base; design; design and construction; enterotoxin LT; experience; fliC gene product; fungus; immunogenic; immunogenicity; in vivo; mortality; neutralizing antibody; novel; pathogen; preclinical study; prevent; protective efficacy; receptor binding; rectal; response; success; therapeutic vaccine; vaccine candidate; vaccine efficacy

DESCRIPTION (provided by applicant): Clostridium difficile is a spore-forming Gram-positive anaerobic bacillus, and is the leading cause of nosocomial diarrhea and colitis in the industrialized world with more than 300,000 cases of C. difficile- associated diarrhea (CDAD) reported each year in the United States alone. Broad spectrum antibiotic usage, hospitalization, advanced age and comorbidities increase the risk for acquiring CDAD. Symptoms result from the production of two potent C. difficile toxins (toxin A and toxin B). Studies with humans have shown that protection against disease and relapse correlates predominantly with the presence of serum IgG responses directed against toxin A and less strongly with toxin B. No vaccine effective at preventing C. difficile disease is currently commercially available, and measures to prevent CDAD through patient isolation and implementation of hand-hygiene and contact precautions have had variable and often limited success. We propose to develop a recombinant C. difficile protein vaccine by fusing the non-toxic receptor binding domain (RBD) of toxin A or toxin B with C. difficile flagellar proteins, FliC and FliD. The RBD of toxin A and toxin B have been shown to induce neutralizing antibodies in immunized mice. The C. difficile FliD and FliC are involved in adherence and gut colonization, and FliC is a potent Toll-like receptor (TLR) 5 ligand. TLRs are a family of pattern recognition receptors that recognize structural components shared by bacteria, fungi and viruses. TLRs when bound to their ligands such as flagellin can trigger innate responses as well as facilitate in the development of adaptive immunity. Several promising experimental vaccines have been tested with flagellin either as an antigen or as an adjuvant. It still remains to be determined whether anti-flagellin immune responses can prevent C. difficile colonization and whether activation through TLR signaling plays a significant role in human responses against a C. difficile toxin vaccine. We hypothesize that the incorporation of flagellar proteins and toxins in a vaccine could provide protection against colonization as well as disease progression. Key milestones will be to address whether the combination vaccine using toxins and flagellar proteins can exhibit robust immunogenicity in vaccinated mice, resulting in the production of toxin neutralizing antibodies, a correlate of vaccine efficacy, and anti-flagellar antibodies that can prevent colonization. Since C difficile isa mucosal pathogen, several routes of immunization that target the mucosal surface such as intra- rectal, intranasal and transcutaneous will be compared to parenteral immunization in the presence of mucosal adjuvants such as heat labile enterotoxin, LT (r192g). The most promising vaccines will then be evaluated in challenge and protection studies. Challenge studies against multiple C. difficile strains in the mouse and the hamster model of bacterial infection will be performed to evaluate C. difficile colonization and protection against CDAD.

描述（由申请人提供）：艰难梭菌是一种形成孢子的革兰氏阳性厌氧杆菌，是工业化国家院内腹泻和结肠炎的主要原因，据报道有超过 300,000 例艰难梭菌相关性腹泻 (CDAD) 病例每年仅在美国。广谱抗生素的使用、住院、高龄和合并症会增加患 CDAD 的风险。症状是由两种强效艰难梭菌毒素（毒素 A 和毒素 B）的产生引起的。对人类的研究表明，预防疾病和复发主要与针对毒素 A 的血清 IgG 反应相关，而与毒素 B 的血清 IgG 反应不太相关。目前，市场上还没有有效预防艰难梭菌疾病的疫苗，也没有预防 CDAD 的措施通过患者隔离以及手部卫生和接触预防措施的实施，取得了不同程度且往往有限的成功。 我们建议通过将毒素 A 或毒素 B 的无毒受体结合域 (RBD) 与艰难梭菌鞭毛蛋白 FliC 和 FliD 融合来开发重组艰难梭菌蛋白疫苗。毒素 A 和毒素 B 的 RBD 已被证明可以在免疫小鼠中诱导中和抗体。艰难梭菌 FliD 和 FliC 参与粘附和肠道定植，FliC 是一种有效的 Toll 样受体 (TLR) 5 配体。 TLR 是一个模式识别受体家族，可识别细菌、真菌和病毒共有的结构成分。当 TLR 与其配体（如鞭毛蛋白）结合时，可以触发先天反应并促进适应性的发展 免疫。已经用鞭毛蛋白作为抗原或佐剂测试了几种有前途的实验疫苗。抗鞭毛蛋白免疫反应是否可以阻止艰难梭菌定植以及通过 TLR 信号传导激活是否在人类针对艰难梭菌毒素疫苗的反应中发挥重要作用仍有待确定。我们假设在疫苗中加入鞭毛蛋白和毒素可以提供针对定植和疾病进展的保护。关键的里程碑将是解决使用毒素和鞭毛蛋白的组合疫苗是否可以在接种疫苗的小鼠中表现出强大的免疫原性，从而产生毒素中和抗体（疫苗功效的相关性）以及可以防止定植的抗鞭毛抗体。由于艰难梭菌是粘膜病原体，因此将针对粘膜表面的几种免疫途径（例如直肠内、鼻内和经皮）与在粘膜佐剂（例如不耐热肠毒素LT (r192g))存在下的肠胃外免疫进行比较。然后将在攻击和保护研究中评估最有前途的疫苗。将在小鼠和仓鼠细菌感染模型中进行针对多种艰难梭菌菌株的攻击研究，以评估艰难梭菌定植和针对 CDAD 的保护作用。