Immunological Cross Reactivity of Eaea (Intimin) from E. coli That Cause Attaching and Effacing Lesions in Humans and Rabbits

Abstract

A number of enteric diarrheal pathogens, including Hafnia alvei, enteropathogenic (EPEC) and enterohemmorrhagic (EHEC) Escherichia coli in humans, Citrobacter rodentium in mice and REPEC (rabbit EPEC) have the ability to induce major histopathologic changes on intestinal epithelial cells. These attaching and effacing (A/E) lesions are characterized by effacement of microvilli and marked cytoskeletal re-arrangements, including “pedestal” formation around the bacteria and accumulation of polymerized actin in the area of close attachment. The ability of these bacteria to form close attachment is mediated by intimin, a ~100 kDa outer membrane protein (OMP) believed to mediate close attachment, probably through binding of the C-terminal region of the protein to intestinal receptors. Intimin shows some sequence similarity to invasin, an OMP of Yersinia spp., responsible for mediating cell invasion. Sequence comparisons of RDEC-l(REPEC) intimin to intimins from EPEC O127:H6 and EHEC O157:H7 show ~90% homology at the amino terminal region, but only 65% homology at the carboxy terminal region of the protein. It is this divergent C-terminal region of the protein which is believed to play a role in the biological activity of intimin. To determine whether intimin from other E. coli are related to RDEC-1 intimin, antisera to the C-terminal region of RDEC-1 intimin was used to screen OMP extracts from a variety of E. coli isolates.