The locus for enterocyte effacement (LEE) of enteropathogenic Escherichia coli (EPEC) from dogs and cats

Enteropathogenic Escherichia coli (EPEC) produce attaching and effacing les ions. The genes responsible for this lesion are clustered on the chromosome forming a 35.5 kilobase pathogenesis island called LEE. The LEE was identi fied: characterized and completely sequenced from the human EPEC strain E23 48/69. The LEE carries genes coding for: a type III secretion system (genes esc and sep), the translocated intimin receptor (gene tir), the outer memb rane protein intimin (gene eae) and the E. coli secreted proteins EspA, Esp B, and EspD (genes esp). In addition to man and farm animals, EPEC are also isolated from dogs and cats. We studied structurally and functionally the LEE of dog and cat EPEC. First, we used four probes scattered along the LEE to identify the presence of a LEE in canine and feline EPEC isolates. Seco nd, by PCR, we checked the presence of genes homologous to ene, sep, esp, a nd tir genes in these strains. Third, since the four types of ene and tir g enes were described, we developed a multiplex PCR in order to determine the type of eae and tir genes present in each strain. Fourth, we determined by PCR the site of the LEE insertion on the chromosome. Fifth, we tested seve ral of the canine EPEC in their capacity to induce attaching and effacing l esions in the rabbit intestinal loop assay. We can conclude from this study : first, that the a LEE-like structure is present in all tested strains and that it contains genes homologous to esp, sep, tir, and eae genes; second, that there is some preferential associations between the type of eae gene and the type of tir gene present in a strain: third, that the majority of t he tested strains contained a LEE located elsewhere on the chromosome in co mparison to the human EPEC strain E2348/69: and fourth that dog EPEC were a ble to induce attaching and effacing lesions in rabbit ileal loop assay.