Structure-function studies on Clostridium difficile large toxins

艰难梭菌大毒素的结构-功能研究

• 批准号: MR/K027123/1
• 负责人: Ravi Acharya
• 金额: $ 78.51万
• 依托单位: University of Bath
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2014
• 资助国家: 英国
• 起止时间: 2014 至 无数据
• 项目状态: 已结题
• 来源: https://gtr.ukri.org/projects?ref=MR%2FK027123%2F1
• 关键词: Structure; function; studies; Clostridium; difficile

Clostridium difficile infection (CDI) is the most important cause of hospital-acquired diarrhoea. C. difficile is an anaerobic bacterium that is present in the gut of up to 3% of healthy adults and 66% of infants. However, C. difficile rarely causes problems in children or healthy adults, as it is kept in check by the normal bacterial population of the intestine. When certain antibiotics disturb the balance of bacteria in the gut, C. difficile can multiply rapidly and produce toxins which cause illness. CDI ranges from mild to severe diarrhoea and to, more unusually, severe inflammation of the bowel (known as pseudomembranous colitis). People who have been treated with broad spectrum antibiotics (those that affect a wide range of bacteria), people with serious underlying illnesses and the elderly are at greatest risk - over 80% of CDIs reported are in people aged over 65 years. CDI is usually spread on the hands of healthcare staff and other people who come into contact with infected patients or with environmental surfaces (e.g. floors, bedpans, toilets) contaminated with the bacteria or its spores. Spores are produced when C. difficile bacteria encounter unfavourable conditions, such as being outside the body. They are very hardy and can survive on clothes and environmental surfaces for long periods. However, with better hospital care and hygiene awareness, the number of cases recorded in 2010 by the Health Protection Agency (the agency that identifies and responds to health hazards and emergencies caused by infectious disease) has reduced, but still remains a major threat and significant economic burden to the NHS. With evidence of growing antibiotic resistance for metronidazole and vancomycin (two well known antibiotics used in the clinic) there is an urgent need for the development of alternative therapeutics. This is particularly true for cases of severe CDI for which there are currently very limited treatment options. Changes in epidemiology and disease severity, particularly in respect of strains that have emerged over the last ten years (e.g. the 027 ribotype), highlight the need to understand more about this worldwide pathogen. Through an academic collaboration with Dr. Clifford Shone at the Health Protection Agency, Porton Down (UK), we have set about elucidating the molecular structures of some of the key molecules implicated in CDI such as C. difficile major toxins (Toxin-A and-B and the binary toxin). Currently there are considerable gaps in our understanding of how these protein molecules of C. difficile cause disease and the also the mechanism by which antibodies produced against these toxins, neutralise their activity. A greater understanding of these aspects of toxin structure and action would greatly aid the design of new therapeutics including improved vaccines, therapeutics based on antibodies and therapeutic based on small molecule inhibitors (drugs).

艰难梭菌感染（CDI）是医院获得性腹泻的最重要原因。C.艰难梭菌是一种厌氧细菌，存在于高达3%的健康成人和66%的婴儿的肠道中。然而，C.艰难梭菌很少在儿童或健康成人中引起问题，因为它被肠道的正常细菌群控制。当某些抗生素扰乱肠道内细菌的平衡时，C。艰难梭菌可以迅速繁殖并产生导致疾病的毒素。CDI的范围从轻度到重度腹泻，更不寻常的是，严重的肠道炎症（称为伪膜性结肠炎）。接受过广谱抗生素（影响多种细菌的抗生素）治疗的人，患有严重基础疾病的人和老年人的风险最大-超过80%的CDIs报告发生在65岁以上的人群中。CDI通常传播在医护人员和其他与受感染患者接触的人的手上，或与被细菌或其孢子污染的环境表面（例如地板，便盆，厕所）接触的人。C.艰难梭菌遇到不利的条件，如在体外。它们非常哈代，可以在衣服和环境表面上存活很长时间。然而，随着医院护理和卫生意识的提高，2010年健康保护局（负责识别和应对传染病造成的健康危害和紧急情况的机构）记录的病例数量有所减少，但仍然是对国民保健制度的一个主要威胁和重大经济负担。随着对甲硝唑和万古霉素（临床上使用的两种众所周知的抗生素）的抗生素耐药性不断增加的证据，迫切需要开发替代疗法。对于目前治疗选择非常有限的重度CDI病例尤其如此。流行病学和疾病严重程度的变化，特别是在过去十年中出现的菌株（例如027核糖体），突出了需要更多地了解这种全球性病原体。通过与英国健康保护局的Clifford Shone博士的学术合作，我们已经着手阐明CDI中涉及的一些关键分子的分子结构，如C。艰难梭菌主要毒素（毒素A和毒素B以及二元毒素）。目前，我们对这些蛋白质分子是如何与C.艰难梭菌引起疾病，也是产生抗体对抗这些毒素的机制，中和它们的活性。对毒素结构和作用的这些方面的更好理解将极大地帮助设计新的治疗剂，包括改进的疫苗、基于抗体的治疗剂和基于小分子抑制剂（药物）的治疗剂。

项目成果

High prevalence of subclass-specific binding and neutralizing antibodies against Clostridium difficile toxins in adult cystic fibrosis sera: possible mode of immunoprotection against symptomatic C. difficile infection.

• DOI: 10.2147/ceg.s133939
• 发表时间: 2017
• 期刊: Clinical and experimental gastroenterology
• 影响因子: 2.4
• 作者: Monaghan TM;Negm OH;MacKenzie B;Hamed MR;Shone CC;Humphreys DP;Acharya KR;Wilcox MH
• 通讯作者: Wilcox MH

The molecular structure of the glycoside hydrolase domain of Cwp19 from Clostridium difficile.

• DOI: 10.1111/febs.14310
• 发表时间: 2017-12
• 期刊: The FEBS journal
• 作者: Bradshaw WJ;Kirby JM;Roberts AK;Shone CC;Acharya KR
• 通讯作者: Acharya KR

Functional significance of active site residues in the enzymatic component of the Clostridium difficile binary toxin.

• DOI: 10.1016/j.bbrep.2016.08.011
• 发表时间: 2016-12
• 期刊: Biochemistry and biophysics reports
• 影响因子: 2.7
• 作者: Davies AH;McGlashan J;Posner MG;Roberts AK;Shone CC;Acharya KR
• 通讯作者: Acharya KR

The structure of the S-layer of Clostridium difficile.

• DOI: 10.1007/s12079-017-0429-z
• 发表时间: 2018-03
• 期刊: Journal of cell communication and signaling
• 影响因子: 4.1
• 作者: Bradshaw WJ;Roberts AK;Shone CC;Acharya KR
• 通讯作者: Acharya KR