Environmentally-induced virulence changes in enterhemorrhagic escherichia coli

环境引起的肠出血性大肠杆菌毒力变化

• 批准号: 238684-2006
• 负责人: BarnettFoster, Debora
• 金额: $ 3.22万
• 依托单位: Ryerson University
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2008
• 资助国家: 加拿大
• 起止时间: 2008-01-01 至 2009-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=394025
• 关键词: Environmentally; induced; virulence; changes; enterhemorrhagic

This application is for funding to support the investigation of stress-induced virulence changes in enterohemorrhagic (EHEC) E.coli O157:H7. This enteric pathogen is a leading cause of bloody diarrhea, hemorrhagic colitis and hemolytic uremic syndrome. During ingestion, EHEC is exposed to several stresses including gastric acid as well as bile salts and short chain fatty acids in the intestine. It can also be exposed to stress during acid-washing of meat carcasses. We have found that acid and bile salt stress significantly enhance adhesion of EHEC and a closely related pathogen, enteropathogenic E.coli(EPEC),to human epithelial cells. We have also identified a bacterial protein and a host cell lipid that play a role in the enhanced adhesion of acid-stressed EPEC. The goal of this proposal is to identify genes and pathways encompassing stress-induced EHEC virulence changes. Using DNA microarrays, we will examine the mRNA expression profiles of EHEC before and after exposure to acid, bile salts, and short chain fatty acids to identify bacterial proteins responsible for the stress-induced virulence changes. Differential gene expression will be confirmed by quantitative real-time PCR and protein changes will be validated by 2D gel electrophoresis and electrospray tandem mass spectrometry. To confirm the role of stress-induced genes in EHEC virulence, we will construct mutants defective in the individual genes and test them for changes in virulence phenotype before and after stress exposure. We will also identify regulators of the virulence genes using transposon mutagenesis. Stress-induced changes in virulence of EHEC O157:H7 can have a profound impact on the development and progression of the disease and therefore provide exciting targets to modulate the virulence potential of this pathogen. This targeted approach recognizes the value of commensal bacteria by permitting selective attenuation of EHEC O157:H7 while maintaining the nonpathogenic, commensal bacteria that play a role in preventing infection. The research will also identify and characterize the infection risk associated with sublethal environmental stress including food processing practices.

本申请旨在资助研究应激诱导的肠出血性 (EHEC) 大肠杆菌 O157:H7 毒力变化。这种肠道病原体是血性腹泻、出血性结肠炎和溶血性尿毒症综合征的主要原因。在摄入过程中，肠出血性大肠杆菌会受到多种压力，包括胃酸以及肠道内的胆汁盐和短链脂肪酸。在酸洗肉尸体的过程中，它也会受到压力。我们发现酸和胆盐应激显着增强了肠出血性大肠杆菌和密切相关的病原体肠病性大肠杆菌（EPEC）对人类上皮细胞的粘附。我们还鉴定了一种细菌蛋白和一种宿主细胞脂质，它们在增强酸胁迫 EPEC 的粘附方面发挥作用。该提案的目标是确定包含应激诱导的肠出血性大肠杆菌毒力变化的基因和途径。使用 DNA 微阵列，我们将检查 EHEC 在暴露于酸、胆汁盐和短链脂肪酸之前和之后的 mRNA 表达谱，以确定导致应激诱导毒力变化的细菌蛋白。差异基因表达将通过定量实时 PCR 进行确认，蛋白质变化将通过 2D 凝胶电泳和电喷雾串联质谱进行验证。为了确认应激诱导基因在肠出血性大肠杆菌毒力中的作用，我们将构建单个基因有缺陷的突变体，并测试它们在应激暴露前后毒力表型的变化。我们还将使用转座子诱变来鉴定毒力基因的调节因子。应激诱导的 EHEC O157:H7 毒力变化可能对该疾病的发生和进展产生深远影响，因此为调节该病原体的毒力潜力提供了令人兴奋的目标。这种有针对性的方法通过允许选择性减弱 EHEC O157:H7，同时保留在预防感染中发挥作用的非致病性共生细菌，认识到共生细菌的价值。该研究还将确定和描述与亚致死环境压力（包括食品加工实践）相关的感染风险。