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 infections are characterised by the formation of attaching and effacing (AE) lesions on intestinal epithelial cells. Secretion of extracellular proteins (EspA, EspB, and EspD) via a type III secretion apparatus is necessary for the formation of the AE lesions by human EPEC. In this study, we show that bovine EPEC and EHEC are also able to secrete polypeptides homologous to the already described Esp proteins, most probably via a type III secretion system. Bovine EPEC and EHEC strains present two different secretion profiles of Esp proteins which correlate to the pathotypes of the esp genes as determined by PCR. We also demonstrate that genes encoding secreted proteins, present in the LEE of two bovine strains, are organised in the same way as in the human EPEC strain E2348/69.