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

Author(s):Show less -

Yamamoto, Denise ^{[1, 2]} ; Hernandes, Rodrigo T. ^{[1, 2]} ; Blanco, Miguel ^[3] ; Greune, Lilo ^[2] ; Schmidt, M. Alexander ^[2] ; Carneiro, Sylvia M. ^[4] ; Dahbi, Ghizlane ^[3] ; Blanco, Jesus E. ^[3] ; Mora, Azucena ^[3] ; Blanco, Jorge ^[3] ; Gomes, Tania A. T. ^[1]

Affiliation

^[1] Univ Fed Sao Paulo, BR-04023062 Sao Paulo - Brazil

^[2] Univ Munster, Inst Infektiol, Zentrum Mol Biol Entzundung, Munster - Germany

^[3] Univ Santiago de Compostela, Fac Vet, Dept Microbiol & Parasitol, E Coli Reference Lab LREC, Lugo - Spain

^[4] Inst Butantan, Lab Biol Celular, Sao Paulo - Brazil

• Document type: Journal article
• Source: BMC Microbiology; v. 9, JUL 21 2009.
• Web of Science Citations: 24

Abstract

Background: 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. Results: 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. Conclusion: Some aEPEC strains may invade intestinal cells in vitro with varying efficiencies and independently of the intimin sub-type. (AU)