A study of K88-mediated haemagglutination by enterotoxigenic Escherichia coli (ETEC)

The K88 fimbrial adhesin is a major virulence determinant of certain strains of enterotoxigenic Escherichia coli (ETEC) that infect and colonise neonatal pigs. This study investigates the haemagglutination properties of all three serotypes (ab, ac and ad) with eleven erythrocyte species. Wide variation in the haemagglutination properties indicated differences in both the K88 receptor and adhesin structure. In particular, the receptor binding properties of E. coli serotype K88ad were significantly different from both K88ab and K88ac. K88-mediated haemagglutination was inhibited strongly by a range of glucosides, glucosamine, chondrosine and pig gastric mucin but only weakly by mamman and heparin. The most effective inhibitor was n-dodecyl-beta-D-glucopyranoside which prevented haemagglutination at a concentration of 0.72 mM. It is hypothesised that the potent inhibition observed with glucosides may be due to interference with hydrophobic interactions and is not necessarily specific.