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) 是一种人畜共患细菌病原体，可在牛体内定殖，但不会在牛宿主中引起疾病​​。然而，如果细菌进入食物链并感染人类宿主，则可能导致严重的健康并发症，有时甚至导致死亡。如果我们能够阻止细菌在牛体内定植和持续存在，那么我们就可以减轻这种病原体进入食物链的负担。对于食用前不会煮熟的食物（例如未经高温消毒的奶酪），这一点尤其重要。干预措施，特别是疫苗，已经进行了试验，但商业成功有限。我们建议开发一种噬菌体（噬菌体）治疗方法，可以选择性地去除牛体内的 O157 细菌。噬菌体是仅感染和杀死细菌的病毒。它们非常特殊，它们的生命周期依赖于识别细菌宿主外部的受体，通常是蛋白质。一旦它们找到了受体，它们就可以附着、注入 DNA、在细菌细胞内复制，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相互交战，因此两者都不断进化以能够抵抗感染（细菌）并能够重新感染（噬菌体）。我们可以在实验室中筛选出能够在实验室培养条件下感染并杀死O157菌株的噬菌体。然而，在宿主体内，细菌将处于与实验室营养丰富的培养基中不同的生理状态。这意味着在这些不同的营养限制条件下以及当细菌附着在上皮细胞上并且生长更缓慢时，其表面上的特定受体可能会有所不同。此前曾尝试将噬菌体干预作为牛中 O157 的对照，但成效有限。我们有证据表明这是因为宿主细菌的生理状态与选择噬菌体的实验室条件相差太大。我们建议通过了解细菌在牛体内时其表面表达哪些受体对于宿主，我们可以选择在用作干预策略时活跃的噬菌体，以从牛身上去除/减少 O157，从而保护食物链。通过对宿主细菌的生理学有了更深入的了解，我们可以在实验室中开发更好地代表“宿主”条件的模型。然后，我们可以使用这些实验室模型来测试噬菌体活性并创建可在 O157 定植的牛中进行测试的噬菌体组合。这不仅将解决 O157 控制中未满足的需求，而且将成为噬菌体疗法可针对的其他细菌感染的典范，包括抗生素耐药性感染。