Identification of two porcine brush border glycoproteins that bind the K88ac adhesin of Escherichia coli and correlation of these glycoproteins with the adhesive phenotype.

In this study, we identified two brush border glycoproteins (210 and 240 kDa) that bind both K88ac+ Escherichia coli and purified K88ac adhesin. The specificity of these binding glycoproteins for the K88ac adhesin was demonstrated in studies in which the binding of 35S-labeled K88ac+ E. coli and biotinylated K88ac adhesin to these glycoproteins was blocked in the presence of a 100-fold molar excess of unlabeled K88ac adhesin but not in the presence of the K99 adhesin. Pretreatment of adhesive brush borders with sodium metaperiodate destroyed both binding activities, indicating that the interaction between the K88ac adhesin and the binding glycoproteins requires the glycoprotein carbohydrate moiety. It was demonstrated previously that K88ac+ E. coli binds to adhesive brush borders but not to nonadhesive brush borders (R. Sellwood, R. A. Gibbons, G. W. Jones, and J. M. Rutter, J. Med. Microbiol. 8:405-411, 1975). In the present study, brush borders isolated from 10 different pigs were tested first for brush border adhesiveness and then for the presence of the binding glycoproteins. In all cases, the binding glycoproteins were detected only in the adhesive brush border preparations. These two binding glycoproteins may be the receptors used by K88ac+ ETEC to adhere to intestinal brush border cells. Their presence on adhesive brush borders and absence on nonadhesive brush borders may be the basis for resistance and susceptibility of pigs to K88ac+ ETEC infections.