Investigation on the potential involvement of Pil fimbriae in the adherence efficiency of enteropathogenic Escherichia coli (EPEC) strains that co-express the localized and aggregative adherence patterns to HeLa cells.
Enteropathogenic Escherichia coli (EPEC) produce characteristic intestinal lesions (attaching/effacing lesions, A/E), being identified by the production of the localized adherence (LA+) pattern in HeLa cells. LA+ EPEC strains of the O119:H6 serotype constituted, for many decades, one of the most frequent childhood diarrheal agents in our environment. Curiously, we have identified O119:H6 strains producing LA and aggregative adherence (AA) simultaneously (LA/AA+). However, AA is characteristic of strains of the enteroaggregative E. coli (EAEC) pathotype, which colonize the human intestine forming prominent biofilms. We recently demonstrated that the horizontal transfer of an ~ 80 kb plasmid (pGM80) of an O119:H6 LA/AA+ strain to a non-adherent E. coli strain resulted in AA+ transconjugants. pGM80 sequencing revealed the presence of the pil operon, which encodes a variant of the AA-associated Pil fimbriae of some EAEC strains. Therefore, we questioned whether the acquisition by EPEC of AA-encoding genes could result in more virulent clones. However, Pil production as well as their involvement in the AA phenotype of LA/AA+ strains requires confirmation and studies on the distribution of pil in LA+ and LA/AA+ EPEC strains are needed. In this study, we intend to demonstrate the production of Pil and its involvement in the AA phenotype and biofilm production in LA/AA+ EPEC strains and to investigate and compare the distribution and expression of the pil operon in LA+ and LA/AA+ EPEC strains of different serotypes and geographic regions. The pil operons of other LA/AA+ strains will be compared by sequencing and the pGM80 transfer potential for strains of other EPEC serotypes will be evaluated. (AU)
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