Development of a universal intimin antiserum and PCR primers

Enteropathogenic Escherichia coli (EPEC) and enterohemorrhagic E. coli (EHEC) constitute a significant risk to human health worldwide. A hallmark of both pathogens is their ability to produce characteristic attaching-and- effacing (A/E) lesions in intestinal epithelial cells. Genes encoding A/E lesion formation map to a chromosomal pathogenicity island termed the locus of enterocyte effacement (LEE). Intimin, an LEE-encoded bacterial adhesion molecule, mediates the intimate bacterium-host cell interaction characteristic of A/E lesions. On the basis of characterization of the C- terminal 280-amino-acid cell binding domain of intimin (Int280_{661- 939}), four distinct Int280 types (types α, γ, and δ) have been identified. Importantly, Int280α and Int280β antisera specifically recognized their respective intimin types. Using a conserved region of the intimin molecule (Int_388-667) and primers synthesized to generate the recombinant Int_388-667, we have now generated universal intimin antiserum and PCR primers that are reactive with the different intimin types expressed by both human and animal A/E lesion-forming strains. Use of immunogold electron microscopy to visualize intimin on the surfaces of EPEC and EHEC strains revealed, in general, a uniform distribution on the bacterial cell surface. However, a filamentous staining pattern was observed with a few strains expressing intimin γ. Cloning of the intimin eae gene from one such strain (strain ICC57) into strain CVD206, an EPEC strain which harbors a null deletion in eae, produced a uniform intimin staining pattern indicating that, if the filamentous staining pattern defines a filamentous form of intimin γ, it is dependent upon the genetic background of the strain and is not a feature of the intimin molecule.