DETECTION OF INTIMIN-ALPHA, INTIMIN-BETA, INTIMIN-GAMMA, AND INTIMIN-DELTA, 4 INTIMIN DERIVATIVES EXPRESSED BY ATTACHING AND EFFACING MICROBIAL PATHOGENS

Intimins are outer membrane proteins expressed by enteric bacterial pa thogens capable of inducing intestinal attachment-and-effacement lesio ns. A eukaryotic cell-binding domain is located within a 280-amino-aci d (Int280) carboxy terminus of intimin polypeptides. Polyclonal antise rum was raised against Int280 from enteropathogenic Escherichia coli ( EPEC) serotypes O127:H6 and O114:H2 (anti-Int280-H6 and anti-Int-280-H 2, respectively), and Western blot analysis was used to explore the im munological relationship between the intimin polypeptides expressed by different clinical EPEC and enterohemorrhagic E. coli (EHEC) isolates , a rabbit diarrheagenic E. coli strain (RDEC-1), and Citrobacter rode ntium. Anti-Int280-H6 serum reacted strongly with some EPEC serotypes, whereas anti-Int280-H2 serum reacted strongly with strains belonging to different EPEC and EHEC serotypes, RDEC-1, and C. rodentium. These observations were confirmed by using purified Int280 in an enzyme-link ed immunosorbent assay and by immunogold and immunofluorescence labell ing of whole bacterial cells. Some bacterial strains were recognized p oorly by either antiserum (e.g., EPEC O86:H34 and EHEC O157:H7). By us ing PCR primers designed on the basis of the intimin-encoding eae gene sequences of serotype O127:H6, O114:H2, and O86:H34 EPEC and serotype O157:H7 EHEC, we could distinguish between different eae gene derivat ives. Accordingly, the different intimin types were designated alpha, beta, delta, and gamma, respectively.