PHAGE-ENCODED FUNCTIONS IN ENTEROHEMORRHAGIC E.COLI

肠出血性大肠杆菌中噬菌体编码的功能

• 批准号: 6374731
• 负责人: GAIL E CHRISTIE
• 金额: $ 13.3万
• 依托单位: VIRGINIA COMMONWEALTH UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2000
• 资助国家: 美国
• 起止时间: 2000-09-30 至 2004-09-29
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6374731
• 关键词: Escherichia coli 0157:H7; Escherichia coli infections; bacterial food poisoning; bacterial genetics; bacterial proteins; bacterial toxins; bacterial virus; enzyme linked immunosorbent assay; gastrointestinal infection; gene expression; laboratory mouse; protein kinase; virulence

DESCRIPTION (adapted from the application) The long-term goal of this research is to understand the role of temperate phages in, and the contribution of phage-encoded gene products to, the virulence of enterohemorrhagic Escherichia coli (EHEC). EHEC are emerging foodborne pathogens that have caused large-scale outbreaks of gastrointestinal illness in developed countries during the past two decades. Intestinal infection can lead to diarrhea, hemorrhagic colitis or more severe systemic complications, such as hemolytic uremic syndrome. The production of Shiga toxins by EHEC strains plays an important role in the development of serious complications following EHEC infection. Two immunologically distinct Shiga toxins, designated Stx1 and Stx2, have been identified among clinical E. coli isolates of many serotypes. Genes for both Shiga toxin types in E. coli have been shown to be encoded on lysogenic lambdoid bacteriophages. These Shiga toxin-encoding phages have played an important role in transmitting the stx genes during the evolution of Stx-producing enteric pathogens, and continue to be involved in ongoing dissemination of Shiga toxin genes to new hosts. In addition, recent studies have shown that the toxin genes appear to be integrated into the lytic circuitry of these phages in such a way that prophage induction leads to increased toxin gene expression and concomitant release of toxin by host cell lysis. One aim of the experiments outlined in this application is to define more clearly the roles of phage-encoded functions in toxin gene expression and toxin release. A second aim of the application is to investigate other phage-encoded genes that are postulated to play roles in lysogenic conversion. The products of these genes may affect processes, such as colonization or immune evasion, that could contribute to the virulence of lysogenic bacteria. Using the Stx2-encoding phage 933W, which has been sequenced in its entirety, directed mutations in individual genes will be constructed. The effects of these mutations on Shiga toxin production or other interactions with host cells will be assessed in vitro, and effects on virulence using a mouse model system will be determined.

描述（改编自应用程序） 这项研究的长期目标是了解温和的作用， 以及噬菌体编码的基因产物对 肠出血性大肠杆菌（EHEC）的毒力。肠出血性大肠杆菌 食源性病原体导致胃肠道疾病大规模爆发， 在过去的二十年里，发达国家的疾病。肠 感染可导致腹泻、出血性结肠炎或更严重的全身性 并发症，如溶血性尿毒综合征。滋贺的生产 肠出血性大肠杆菌菌株产生的毒素在严重的 EHEC感染后的并发症两种免疫学上不同的滋贺 Stx 1和Stx 2是临床大肠杆菌中的两种毒素。杆菌 许多血清型的分离株。两种滋贺毒素的基因在大肠杆菌中均存在。大肠杆菌有 已被证明在溶原性类噬菌体上编码。这些滋贺 编码毒素的细菌在传播stx中起着重要作用 在Stx产生肠道病原体的进化过程中， 参与滋贺毒素基因向新宿主的传播。在 此外，最近的研究表明，毒素基因似乎是 整合到这些噬菌体的裂解电路中， 诱导导致增加的毒素基因表达和伴随的 毒素通过宿主细胞裂解。本文概述的实验的一个目的是 应用程序的目的是更清楚地定义噬菌体编码函数在 毒素基因表达和毒素释放。本申请的第二个目的是 研究其他噬菌体编码的基因，这些基因被认为在 溶原性转化这些基因的产物可能会影响过程，如 定植或免疫逃避，这可能有助于毒力 溶原性细菌使用Stx2编码噬菌体933W， 完整测序，个别基因的定向突变将被 构建了这些突变对滋贺毒素产生或其他细胞因子的影响是不确定的。 将在体外评估与宿主细胞的相互作用， 将使用小鼠模型系统测定毒力。