Extrusion of actin-positive strands from HEp-2 and Int 407 cells caused byouter membrane preparations of enteropathogenic Escherichia coli and specific attachment of wild type bacteria to the strands

Enteropathogenic Escherichia coli (EPEC) causes persistent infantile diarrh oea. This nontoxigenic E. coli exhibits a complicated pathogenic mechanism in which its outer membrane proteins and type III secretory proteins damage intestinal epithelium and cause diarrhoea. In accordance with this, our pr evious study using HEp-2 cells demonstrated cytopathic effects caused by ce ll-free outer membrane preparations of EPEC. In this study, we report the e xtrusion of actin-positive strands from HEp-2 and Int 407 cells when treate d with outer membrane preparations. An interesting observation of this work , perhaps relevant to the characteristic localized three-dimensional colony formation of EPEC, is the attachment of a wild type EPEC strain to these a ctin-positive strands.