Invasiveness as a putative additional virulence mechanism of some atypical Enteropathogenic Escherichia coli strains with different uncommon intimin types

• Published in: BMC microbiology Vol. 9; no. 1; p. 146
• Main Authors: Yamamoto, Denise, Hernandes, Rodrigo T, Blanco, Miguel, Greune, Lilo, Schmidt, M Alexander, Carneiro, Sylvia M, Dahbi, Ghizlane, Blanco, Jesús E, Mora, Azucena, Blanco, Jorge, Gomes, Tânia A T
• Format: Journal Article
• Language: English
• Published: England BioMed Central Ltd 21.07.2009; BioMed Central; BMC
• Subjects: Actin Cytoskeleton - metabolism; Adhesins, Bacterial - genetics; Bacteriology; Cell culture; E coli; Enteropathogenic Escherichia coli - classification; Enteropathogenic Escherichia coli - genetics; Enteropathogenic Escherichia coli - pathogenicity; Escherichia coli; Escherichia coli Proteins - genetics; Genes, Bacterial; HeLa Cells; Humans; Microbiology; Microscopy, Electron, Transmission; Physiological aspects; Properties; Proteins; Research article; Serotyping; Tight Junctions - metabolism; Virulence (Microbiology); Virulence - genetics; Brazil; Spain
• ISSN: 1471-2180; 1471-2180
• DOI: 10.1186/1471-2180-9-146

Enteropathogenic Escherichia coli (EPEC) produce attaching/effacing (A/E) lesions on eukaryotic cells mediated by the outer membrane adhesin intimin. EPEC are sub-grouped into typical (tEPEC) and atypical (aEPEC). We have recently demonstrated that aEPEC strain 1551-2 (serotype O non-typable, non-motile) invades HeLa cells by a process dependent on the expression of intimin sub-type omicron. In this study, we evaluated whether aEPEC strains expressing other intimin sub-types are also invasive using the quantitative gentamicin protection assay. We also evaluated whether aEPEC invade differentiated intestinal T84 cells. Five of six strains invaded HeLa and T84 cells in a range of 13.3%-20.9% and 5.8%-17.8%, respectively, of the total cell-associated bacteria. The strains studied were significantly more invasive than prototype tEPEC strain E2348/69 (1.4% and 0.5% in HeLa and T84 cells, respectively). Invasiveness was confirmed by transmission electron microscopy. We also showed that invasion of HeLa cells by aEPEC 1551-2 depended on actin filaments, but not on microtubules. In addition, disruption of tight junctions enhanced its invasion efficiency in T84 cells, suggesting preferential invasion via a non-differentiated surface. Some aEPEC strains may invade intestinal cells in vitro with varying efficiencies and independently of the intimin sub-type.