Enteropathogenic Escherichia coli (EPEC) are important bacterial agents of diarrhea, especially in developing countries, causing a specific histopathologic intestinal lesion (attaching/effacing lesion, A/E). Typical EPEC are carriers of a virulence plasmid (EPEC adherence factor), which is absent in atypical EPEC. tEPEC produce a characteristic pattern of adhesion to HeLa cells called localized adherence pattern (LA). Enteroaggregative E. coli (EAEC) is an emerging enteropathogen, which can lead to persistent diarrhea, by colonizing the intestinal mucosa and forming biofilms. The aggregative adherence pattern (AA) is characteristic of these strains. In studies conducted by our group, we identified the existence of strains of the typical EPEC serotype O119:H6 producing, simultaneously, LA and a pattern similar to AA (AA-like) (LA/AA-like+). Our group also demonstrated that the horizontal transfer of the pGM80 plasmid of an O119: H6 AL/AA-like+ strain to a non-adherent E. coli strain resulted in AA-like+ transconjugants. This plasmid carries the pil operon that encodes a variant of Pil, a type IV fimbriae that is responsible for the AA pattern production in some EAEC strains. However, the distribution of the pil operon in EPEC strains and its expression and capacity to spread to other EPEC serotypes need to be investigated. To contribute to the understanding of the potential of intestinal colonization and to identify more virulent strains of EPEC, this project aims to assess and compare the distribution and expression of the pil operon in typical LA+ and LA/AA-like+ EPEC strains of different serotypes, origins and isolation periods. In addition, it intends to verify the ability of this operon to disseminate to different EPEC serotypes, leading to alterations in their adherence pattern to HeLa cells.
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