ROLE OF INTIMIN IN TISSUE TROPISM AND DAMAGE BY EHEC

描述（改编自应用程序） 肠出血性大肠大肠埃希菌（EHEC）是导致腹泻病的重要原因， 美国的肾衰竭。肠出血性大肠杆菌定植在大肠粘膜上， 肠出血性大肠杆菌感染的肠外表现是由吸收引起的， 通过肠EHEC产生的志贺样毒素（Stx）的上皮。 在附着于结肠上皮的过程中，细菌破坏宿主细胞， 细胞骨架，并在细胞骨架下形成高度组织化的细胞骨架结构。 结合的细菌，称为附着和消退（AE）病变。内膜a 介导紧密宿主细胞附着的细菌外膜蛋白， AE病变形成和完全毒力所需。实验感染 用表达肠致病性E.大肠杆菌（EPEC），一种病原体 感染不同的肠道部位，这表明， 组织向性我们假设：（1）intimin在 确定定殖位点;以及（2）内膜介导的 肠上皮细胞的细胞骨架破坏促进了 肠外感染。为了表征intimin的特征， 影响组织嗜性和促进Stx易位，以下问题 将处理： 1.在适当的调控下表达EPEC紧密蛋白的EHEC菌株是否 对照显示改变的组织向性？肠出血性大肠杆菌染色体eae编码 序列将被EPEC eae编码序列特异性替换，并且 将评估这种改变对组织向性影响。 2.什么样的intimin结构域影响肠道定植部位？的 EPEC内膜蛋白区域负责组织嗜性的差异， 我们希望在Aim 1中找到的菌株将通过分析表达 EHEC/EPEC融合蛋白。 3.产生稳健AE病变的能力是否与粘膜损伤相关 和/或毒素移位同基因EHEC菌株的能力不同， 产生的AE病变将表征粘膜损伤的差异， 在毒素穿过肠上皮移位中。 通过对intimin在细胞凋亡中的作用的详细了解， EHEC的发病机制，拟议的实验可能会导致治疗 旨在尽早防止殖民化的战略， 最大限度地减少感染后肠道对毒素的吸收 确立了习

DESCRIPTION (adapted from the application) Enterohemorrhagic E. coli (EHEC) is an important cause of diarrheal disease and renal failure in the U.S. EHEC colonizes the mucosa of the large bowel, and the extraintestinal manifestations of EHEC infection result from the absorption across the epithelium of Shiga-like toxin (Stx) produced by intestinal EHEC. During attachment to colonic epithelium, the bacterium disrupts the host cell cytoskeleton and forms a highly organized cytoskeletal structure underneath the bound bacterium, termed an attaching and effacing (AE) lesion. Intimin, a bacterial outer membrane protein that mediates tight host cell attachment, is required for AE lesion formation and full virulence. Experimental infection with EHEC expressing intimin from enteropathogenic E. coli (EPEC), a pathogen that infects a different intestinal site, suggested that intimin influences tissue tropism. We postulate that: (1) intimin plays a central role in determining the site of colonization; and that (2) intimin-mediated cytoskeletal disruption of intestinal epithelial cells facilitates delivery of Stx to extraintestinal sites. To characterize the features of intimin that influence tissue tropism and promote Stx translocation, the following questions will be addressed: 1. Does an EHEC strain that expresses EPEC intimin under appropriate regulatory controls demonstrate altered tissue tropism? The EHEC chromosomal eae coding sequence will be specifically replaced by the EPEC eae coding sequence, and the effect of this alteration on tissue tropism will be assessed. 2. What domain of intimin influences the site of intestinal colonization? The region of EPEC intimin responsible for the differences in tissue tropism that we expect to find in Aim 1 will be identified by analyzing strains that express hybrid EHEC/EPEC intimin proteins. 3. Does the ability to generate robust AE lesions correlate with mucosal damage and/or toxin translocation? Isogenic EHEC strains differing in their ability to generate AE lesions will be characterized for differences in mucosal damage and in translocation of toxin across intestinal epithelium. By developing a detailed understanding of the role of intimin in the pathogenesis of EHEC, the proposed experiments may lead to therapeutic strategies designed to prevent colonization at one of the earliest steps or to minimize the intestinal absorption of toxin after infection has been established.