Exploitation of host cells by enteropathogenic Escherichia coli

Microbial pathogens have evolved many ingenious ways to infect their hosts and cause disease, including the subversion and exploitation of target host cells. One such subversive microbe is enteropathogenic Escherichia coil (E PEC), A major cause of infantile diarrhea in developing countries, EPEC pos es a significant health threat to children worldwide, Central to EPEC-media ted disease is its colonization of the intestinal epithelium. After initial adherence, EPEC causes the localized effacement of microvilli and intimate ly attaches to the host cell surface, forming characteristic attaching and effacing (A/E) lesions. Considered the prototype for a family of A/E lesion -causing bacteria, recent in vitro studies of EPEC have revolutionized our understanding of how these pathogens infect their hosts and cause disease, Intimate attachment requires the type Ill-mediated secretion of bacterial p roteins, several of which are translocated directly into the infected cell, including the bacteria's own receptor (Tir). Binding to this membrane-boun d, pathogen-derived protein permits EPEC to intimately attach to mammalian cells, The translocated EPEC proteins also activate signaling pathways with in the underlying cell, causing the reorganization of the host actin cytosk eleton and the formation of pedestal-like structures beneath the adherent b acteria, This review explores what is known about EPEC's subversion of mamm alian cell functions and how this knowledge has provided novel insights int o bacterial pathogenesis and microbe-host interactions, Future studies of A /E pathogens in animal models should provide further insights into how EPEC exploits not only epithelial cells but other host cells, including those o f the immune system, to cause diarrheal disease.