INVASION DETERMINANTS IN ENTEROINVASIVE ESCHERICHIA COLI

某些大肠杆菌菌株能够引起 类似于志贺氏菌病的人类肠道疾病。 其发病机制涉及结肠上皮的侵袭 细胞、细胞内增殖和组织破坏。 肠侵袭性大肠杆菌含有大质粒所需 用于上皮细胞侵入和细胞内增殖。 这 质粒与毒力有相当大的DNA同源性 质粒S.弗莱克斯内里。 本项目的目标是：1）鉴定编码质粒- 进入和增殖所需的决定因素 上皮细胞2）鉴定质粒编码的基因产物 毒性所必需的。 质粒编码 毒力决定因素将由以下因素的组合完成： 克隆和转座子诱变方法。 的表达 克隆的毒力决定簇将使用微细胞进行研究， 大肠coli体外转录翻译系统。 进入肠上皮细胞并在其中存活的能力是 这是许多肠道病原体共有的特征， 肠侵袭性大肠杆菌、志贺氏菌、沙门氏菌和耶尔森氏菌 小肠结肠炎 尽管如此，人们对一个 细菌进入宿主细胞。 一个合理 有一种假说认为，侵入性细菌表面有蛋白质， 与宿主细胞受体发生反应，触发自身的摄取 - 也就是说，它们通过受体介导的 内吞作用 入侵决定因素的鉴定 肠侵袭性E.大肠杆菌的研究将有助于我们更好地理解这一点 E.大肠杆菌和志贺氏菌。 这项工作也应该 促进对发病机制中的事件的研究， 如细胞内存活和增殖。

Certain strains of Escherichia coli are capable of causing a diarrheal disease in man which resembles Shigellosis. Pathogenesis of the disease involves invasion of colonic epithelial cells, intracellular multiplication and tissue destruction. Enteroinvasive Escherichia coli contain a large plasmid required for epithelial cell invasion, and intracellular multiplication. This plasmid shares considerable DNA homology with the virulence plasmid of S. flexneri. The goals of this project are 1) to identify plasmid encoded- determinants required for entry into and multiplication within epithelial cells 2) to identify plasmid-encoded gene products required for virulence. The definition of plasmid-encoded virulence determinants will be accomplished by a combination of cloning and transposon mutagenesis methods. The expression of cloned virulence determinants will be studied using minicells and an E. coli in vitro transcription translation system. The ability to enter and survive within intestinal epithelial cells is a trait shared by a large number of enteric pathogens including enteroinvasive Escherichia coli, Shigella, Salmonella and Yersinia enterocolitica. Despite this, very little is known about how a bacterium gains entry into its host cell. One reasonable hypothesis is that invasive bacteria have proteins on their surface which react with host-cell receptors to trigger their own uptake-- -that is, that they enter the host cell via receptor-mediated endocytosis. The identification of invasion determinants in enteroinvasive E. coli will lead to a better understanding of this entry process both in E. coli and in Shigella. This work should also facilitate research on events in pathogenesis subsequent to invasion such as intracellular survival and multiplication.