Organisation and in vitro expression of esp genes of the LEE (locus of enterocyte effacement) of bovine enteropathogenic and enterohemorrhagic Escherichia coli

Enteropathogenic (EPEC) and enterohemorrhagic (EHEC) Escherichia coli infec tions are characterised by the formation of attaching and effacing (AE) les ions on intestinal epithelial cells. Secretion of extracellular proteins (E spA, EspB, and EspD) via a type III secretion apparatus is necessary for th e formation of the AE lesions by human EPEC. In this study, we show that bo vine EPEC and EHEC are also able to secrete polypeptides homologous to the already described Esp proteins, most probably via a type III secretion syst em. Bovine EPEC and EHEC strains present two different secretion profiles o f Esp proteins which correlate to the pathotypes of the esp genes as determ ined by PCR. We also demonstrate that genes encoding secreted proteins, pre sent in the LEE of two bovine strains, are organised in the same way as in the human EPEC strain E2348/69. (C) 2001 Elsevier Science B.V. All rights r eserved.