Escherichia coli are the most common cause of travelers' and infant diarrhea in lessdeveloped countries. In the present work, among several metabolically labeled human diarrheagenic E. coli strains, enterotoxigenic strains expressing colonization factor antigen II were shown to bind to HT-29 intestinal cell monolayers when these cells were grown in conditions promoting their enterocytic differentiation. Indirect immunofluorescence with fimbrial antisera revealed that pathogen attachment was associated with the production of a specific bacterial adhesin, the E. coli surface antigen CS3. Scanning and transmission electron micrographs showed an apical pattern of colonization, characteristic of enterotoxigenic E. coli infections. The above data were consistent with all observations previously made with human enterocytes obtained from intestinal biopsies. The lectin-carbohydrate nature of this cell-cell recognition mechanism was also established. Bacterial binding to differentiated HT-29 cells was inhibited by a mixture of newborn meconium glycopeptides. By coating the cell layers with the plant agglutinin from Evonymus europaea, pathogen attachment was also

Various caseinoglycopeptide derivatives prepared from mammalian milk were evaluated as inhibitors of hemagglutinations mediated by Actinomyces viscosus Nyl, Streptococcus sanguis OMZ9, and, for comparative purposes, plant lectins from Arachis hypogaea and Bauhinia purpurea. It was found that recognition of the * Corresponding author.

Numerous structural families of naturally occurring glycopeptides and oligosaccharides have been evaluated as potential inhibitors of hemagglutinations mediated by CFA/I‐ and CFA/II‐positive enterotoxigenic Escherichia coli strains. Among the preparations tested were glycopeptides with short O‐linked (mucin‐type) chains, various mixtures containing N‐linked glycans (either oligomannoside‐, hybrid‐ or complex‐type), three fractions of human milk oligosaccharides, and glycopeptides derived from either pooled new‐born meconiums or pooled human red blood cell membranes. In almost all cases, the same inhibitory preparations were active toward all E. coli strains. This emphasizes the close analogy between the carbohydrate specificities of the colonization factors concerned. Such inhibitors always contained lactosamine units in their oligosaccharide backbones, but this structural requirement alone was not sufficient for activity. The glycopeptide mixture derived from human erythrocyte membranes (known to contain blood group‐related carbohydrate antigens carried by a lactosaminoglycan backbone) behaved as a potent hemagglutination inhibitor, especially towards CFA/II‐expressing strains. This last result clearly indicates the structural family in which complex carbohydrates should be selected to establish precisely the specificity of these CFA/II adhesins.