0157:H7 INTIMIN AND STX--PATHOGENESIS IN A MOUSE MODEL

0157：H7 INTIMIN 和 STX——小鼠模型中的发病机制

• 批准号: 6651068
• 负责人: DAVID B SCHAUER
• 金额: $ 33.1万
• 依托单位: MASSACHUSETTS INSTITUTE OF TECHNOLOGY
• 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 2004-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6651068
• 关键词: Escherichia coli 0157:H7; Escherichia coli infections; adhesin; age difference; bacterial toxins; colitis; disease /disorder model; hemolysin; immature animal; laboratory mouse; mature animal; mucosal immunity; pathologic process; virulence

DESCRIPTION (adapted from the application) Since the early 1980s, enterohemorrhagic Escherichia coli (EHEC) has been recognized as a cause of diarrhea and hemorrhagic colitis. The most serious complication of EHEC infection is hemolytic uremic syndrome (HUS), which occurs primarily in children. While it is now recognized that EHEC strains belonging to a variety of serotypes can cause HUS, O157:H7 is the dominant EHEC serotype in many parts of the world and has been the type most commonly associated with foodborne outbreaks. EHEC O157:H7 virulence determinants include shiga toxins (Stx), a chromosomal pathogenicity island called the locus for enterocyte effacement (LEE) that encodes the adhesin intimin and mediates attaching and effacing (AE) activity, as well as a hemolysin (HlyA), a serine protease (EspP), and an plasmid-encoded adhesin with homology to the Clostridium difficile toxin B (Efal). We have developed a mouse model of Citrobacter rodentium colitis that is dependent on LEE-encoded gene products and AE activity for colonization. In this model, suckling mice develop significant mucosal damage in the colon, which is associated with severe colitis and death. Adult mice, on the other hand, develop colonic epithelial hyperplastic and a milder colitis that is typically subclinical. We have recently discovered that an increased inoculum of C. rodentium (10-9 CFU, intragastric) leads to significant mucosal damage and severe colitis in adult mice. We now propose to develop a mouse model of AE colitis for O157:H7 by introducing individual virulence determinants from EHEC O157:H7 into C. rodentium and using these strains to infect adult mice. Specifically, we will 1) characterize the role of O157: H7 intimin in this mouse model of AE colitis, 2) characterize the role of Stx in this mouse model of AE colitis, and 3) characterize the mucosal response to O157:H7 intimin and to Stx in vitro and in vivo. Overall, this work will allow us to test the hypothesis that AE-dependent mucosal damage and colitis influence Stx translocation from the gut. It should also lead to the development of a mouse model for studies of O157:H7 pathogenesis and for testing preventive and therapeutic approaches directed against this important foodborne illness.

描述（改编自应用程序） 自 20 世纪 80 年代初以来，肠出血性大肠杆菌 (EHEC) 已 被认为是腹泻和出血性结肠炎的原因。最严重的 肠出血性大肠杆菌感染的并发症是溶血性尿毒症综合征 (HUS)， 主要发生于儿童。虽然现在人们认识到肠出血性大肠杆菌菌株属于 多种血清型均可引起HUS，其中O157:H7是EHEC的优势血清型 在世界许多地方，并且是最常与 食源性疾病暴发。 EHEC O157:H7 毒力决定因素包括志贺毒素 (Stx)，称为肠上皮细胞基因座的染色体致病岛 擦除（LEE），编码粘附素 intimin 并介导附着和 消除 (AE) 活性，以及​​溶血素 (HlyA)（一种丝氨酸蛋白酶） (EspP)，以及与梭菌同源的质粒编码的粘附素 艰难梭菌毒素 B (Efal)。我们开发了柠檬酸杆菌小鼠模型 依赖于 LEE 编码基因产物和 AE 的啮齿动物结肠炎 殖民活动。在该模型中，乳鼠发育显着 结肠粘膜损伤，与严重结肠炎和死亡有关。 另一方面，成年小鼠会出现结肠上皮增生和 较轻微的结肠炎，通常是亚临床的。我们最近发现 增加 C. rodentium 的接种量（10-9 CFU，胃内）会导致 成年小鼠出现严重的粘膜损伤和严重的结肠炎。我们现在建议 通过引入个体，建立 O157:H7 的 AE 结肠炎小鼠模型 将 EHEC O157:H7 的毒力决定簇引入啮齿类 C. 并使用这些 菌株感染成年小鼠。具体来说，我们将 1）描述角色的特征 O157：H7 intimin 在 AE 结肠炎小鼠模型中的作用，2) 表征 AE 结肠炎小鼠模型中的 Stx，以及 3) 表征粘膜反应 在体外和体内针对 O157:H7 intimin 和 Stx。总体而言，这项工作将 让我们检验以下假设：AE 依赖性粘膜损伤和结肠炎 影响 Stx 从肠道的易位。它还应该导致 开发用于研究 O157:H7 发病机制的小鼠模型 测试针对这一重要问题的预防和治疗方法 食源性疾病。