Role of lactosyl glycan sequences in inhibiting enteropathogenic Escherichia coli attachment

Previously, we found that asialo-lactosamine sequences served as receptors for enteropathogenic Escherichia coli (EPEC) binding to Chinese hamster ova ry (CHO) cells. In the present report, we have extended these earlier resul ts by examining the ability of lactosamine- or fucosylated lactosamine-bovi ne serum albumin (BSA) glycoconjugates to inhibit EPEC, strain E2348/69, bi nding to HEp-2 cells. We found that, consistent with our previous findings with CHO cells, N-atetyllactosamine-BSA was the most effective inhibitor of EPEC localized adherence to HEp-2 cells, with Lewis X-BSA being the next b est inhibitor. Further investigation revealed that coincubating EPEC E2348/ 69 with these BSA glycoconjugates alone caused a decrease in the expression of the bundle-forming pilus structural subunit (BfpA) and intimin by the b acteria. BfpA and intimin expression were reduced to the greatest extent by N-acetyllactosamine-BSA and Lewis X-BSA, respectively. These results sugge st that the glycoconjugate inhibition of EPEC binding to HEp-2 cells might be achieved, wholly or in part, by an active mechanism that is distinct fro m simple competitive antagonism of receptor-adhesin interactions.