YadA mediates specific binding of enteropathogenic Yersinia enterocolitica to human intestinal submucosa

The binding of live Yersinia enterocolitica to frozen sections of human intestine was investigated qualitatively by monitoring the binding of bacteria by using Gram or immunoperoxidase staining as well as quantitatively by a new enzyme immunoassay-on-slide method. We have demonstrated that the binding of various Y. enterocolitica serotypes and Escherichia coli clones to frozen sections of human intestine is mediated by the Yersinia adhesin, YadA. The YadA-mediated binding occurs mainly at the submucosal layer of the intestinal wall and only to a limited extent at the mucosal layer; there binding is mostly to the mucin threads. In addition, partially purified YadA binds to frozen sections with a pattern similar to that of intact bacteria. Collagen, laminin, or partially purified YadA only partially inhibited the YadA-mediated binding of bacteria, presumably because YadA is multifunctional. A combination of collagen and laminin inhibited the binding more efficiently. Therefore, YadA may be involved in the interactions with the extracellular matrix molecules after the invasion of the intestinal tissue.