Defining the physiology of E. coli O157:H7 in cattle to develop phage-based interventions

定义牛体内大肠杆菌 O157:H7 的生理学以开发基于噬菌体的干预措施

• 批准号: BB/X007022/1
• 负责人: David Gally
• 金额: $ 62.41万
• 依托单位: University of Edinburgh
• 依托单位国家: 英国
• 项目类别: Research Grant
• 财政年份: 2023
• 资助国家: 英国
• 起止时间: 2023 至 无数据
• 项目状态: 未结题
• 来源: https://gtr.ukri.org/projects?ref=BB%2FX007022%2F1
• 关键词: Defining; physiology; E.; coli; O157

Escherichia coli O157:H7 (O157) is a zoonotic bacterial pathogen which colonises cattle but does not cause disease in the bovine host. However, if the bacteria passes in to the food chain and infects a human host then it can result in severe health complications and sometimes death. If we can prevent the bacteria from colonising and persisting in cattle then we would reduce the burden of this pathogen entering the food chain. This is especially important in the case of food that won't be cooked before consumption such as unpasteurised cheese. Interventions, particularly vaccines, have been trialled but with limited commercial success. We propose to develop a bacteriophage (phage) treatment that will selectively remove O157 bacteria from the cattle. Phage are viruses that only infect and kill bacteria. They are very specific and their life cycle is dependent on recognising a receptor, often a protein, on the outside of their bacterial host. Once they have found the receptor they can attach, inject their DNA, replicate inside the bacterial cell and then burst out killing the bacterial cell in the process. Phage and bacteria are continually at war with each other in nature and so both continually evolve to be able to resist infection (bacteria) and to be able to reinfect (phage). We can select phage in the laboratory that can infect and kill O157 strains with lab culture conditions. However, in the host the bacteria will be in a different physiological state to that in nutrient rich media in the laboratory. This means the specific receptors on their surface may be different in these different nutrient limited conditions and when the bacteria are attached to epithelial cells and growing more slowly. Phage intervention has previously been attempted as a control for O157 in cattle but with limited success. We have evidence this is because the physiological state of the bacteria in the host is too different from the lab conditions that the phage were selected in. We propose that by understanding which receptors are expressed by the bacteria on their surface when they are in the bovine host we can select phage that will be active when used as an intervention strategy to remove/reduce O157 from cattle and therefore protect the food chain. With a greater understanding of the physiology of the bacteria in its host we can develop models in the laboratory that better represent the 'in host' conditions. We can then use these lab models to test phage activity and create phage combinations that can be tested in cattle colonised with O157. This will not only address an unmet need in O157 control but will be an exemplar for other bacterial infections that could be targeted by phage therapy including antibiotic resistant infections.

大肠杆菌O157：H7（O157）是一种人畜共患的细菌病原体，可在牛宿主中定居但不会引起疾病。但是，如果细菌进入食物链并感染了人类宿主，则可能导致严重的健康并发症，有时甚至死亡。如果我们可以防止细菌在牛中殖民和持续存在，那么我们将减轻这种病原体进入食物链的负担。在食用之前不会烹饪的食物，例如未经巴氏奶酪，这一点尤其重要。干预措施，尤其是疫苗，已受过试验，但商业上的成功有限。我们建议开发一种噬菌体（噬菌体）处理，该处理将有选择地去除牛的O157细菌。噬菌体是仅感染和杀死细菌的病毒。它们非常具体，其生命周期取决于在细菌宿主的外部识别受体，通常是蛋白质。一旦找到了可以连接的受体，注入DNA，将其复制在细菌细胞内，然后在此过程中爆发杀死细菌细胞。噬菌体和细菌在自然界中不断发生战争，因此均不断发展为能够抵抗感染（细菌）并能够重新感染（噬菌体）。我们可以在实验室中选择噬菌体，该实验室可以感染并杀死具有实验室培养条件的O157菌株。但是，在宿主中，细菌的生理状态与实验室中富含营养培养基的生理状态不同。这意味着在这些不同的养分有限的条件下以及细菌附着在上皮细胞上并且生长较慢时，表面上的特定受体可能有所不同。噬菌体干预以前已被试图作为牛O157的控制，但成功率有限。我们有证据表明，这是因为宿主中细菌的生理状态与选择噬菌体的实验室条件太大了。我们建议，当了解哪些受体在牛宿主中被细菌表达在其表面上时，我们可以选择当用作干预策略从牛中使用/减少O157从牛和食物链中使用O157时会活跃的噬菌体，从而可以活跃。有了更了解宿主中细菌的生理学的了解，我们可以在实验室中开发模型，从而更好地代表“宿主”条件。然后，我们可以使用这些实验室模型测试噬菌体活动并创建噬菌体组合，这些组合可以在用O157殖民的牛中测试。这不仅可以解决O157控制中的未满足需求，而且还将是其他细菌感染的典范，这些细菌感染可以通过噬菌体治疗（包括抗生素耐药感染）来靶向。