A comparison of glycan expression and adhesion of mouse-adapted strains and clinical isolates of Helicobacter pylori

Adherence to the mucosal surface, essential for successful colonization of the gastric mucosa by the human pathogen Helicobacter pylori, is predominantly mediated by lectin-like molecules on the Helicobacter binding carbohydrates expressed by host epithelial cells. While clinical isolates of H. pylori do not normally infect mice, some strains have been adapted to colonize this host. We hypothesized that adaptation of H. pylori for colonization of mice may involve alterations in either bacterial surface glycan expression or their glycan-binding properties. Using a panel of lectins, we compared glycan expression on lipopolysaccharides from five mouse-colonizing strains with that of four fresh clinical isolates, but found no association with their ability to infect mice. To compare their adherence to carbohydrates expressed on host epithelial cells, we examined the ability of monosaccharides to block the attachment of mouse-adapted and clinical isolates of H. pylori to human epithelial cell lines. Mannose, N-acetylgalactosamine, N-acetylglucosamine, fucose and sialic acid were all significantly more potent at inhibiting the attachment of mouse-adapted strains to these cell lines than clinical isolates. This might suggest that colonization of the murine mucosa by H. pylori is less dependent on adhesion to host glycans than is the case during human infection.