Exploring the interactions of Enteropathogenic Escherichia coli with intestinal cells in vitro and in vivo

Abstract

Enteropathogenic Escherichia coli (EPEC) comprise two distinct groups of organisms: typical EPEC (tEPEC), which produce the so called the bundle-forming pilus, and atypical EPEC (aEPEC), which are devoid of these fimbriae. Both contain the locus of enterocyte effacement (LEE), a pathogenicity island that encodes a Type Three Secretion System (T3SS) and several effector proteins, which are responsible for the formation of the characteristic attaching and effacing lesion (A/E). For several years, we have explored various aspects of the pathogenicity of EPEC. We have shown that aEPEC present phenotypic and genotypic characteristics far more diverse than those of tEPEC, with some strains showing unusual properties, such as the ability to invade intestinal cells, adhere via flagella and exacerbate mucus production in vivo. Moreover, we have found additional adhesive properties in some strains of classic serotypes of tEPEC (e.g., O119:H6). These facts portray the high plasticity of the E. coli genome and justify the need of a better characterization of how these strains have evolved and the identification of possible newly acquired virulence properties. Using selected strains of aEPEC and tEPEC, in this study, we intend to evaluate: aspects of their adherence to intestinal cells in vitro, focusing on the role of the flagellum, T3SS proteins and effector proteins secreted by this system; the dynamics of their interaction with intestinal cells in vitro and the role of some T3SS- dependent effector proteins on this interaction; the ability of persistence (biofilm production and maintenance in the intracellular millieu), and aspects of their interaction (adherence, invasion, translocation, and/or induction of mucus production) in the intestines of rabbits and rats. (AU)