N-acetylneuraminyllactose-binding fibrillar hemagglutinin of Campylobacter pylori: a putative colonization factor antigen

Campylobacter pylori is the causative agent of gastritis and possibly of peptic and duodenal ulcers in adults. Histological observations show C. pylori attached to gastric epithelium as well as in the mucus layer of the stomach. We found that clinical isolates of C. pylori possess a cell-bound hemagglutinin detectable with human erythrocytes (all phenotypes tested) and those of a variety of animal species. The C. pylori hemagglutinin is antigenic, heat sensitive, and destroyed by pronase and papain but resistant to pepsin and trypsin. The hemagglutinin has fibrillar morphology; C. pylori-erythrocyte interaction displays very intimate contact, which is typical of fibrillae-mediated attachment. Fibrillae were removed from C. pylori by solubilization with N-octylglucose. After partial purification and removal of N-octylglucose by dialysis, the protein reaggregated, with the assembly of fibrillar structures. Hemagglutination inhibition was observed with the sialoproteins fetuin, alpha 2-macroglobulin, and glycophorin A but not with asialofetuin or asialoglycophorin A. The erythrocyte receptor was more sensitive to destruction by a neuraminidase specific for the N-acetylneuraminyl-alpha(2-3)-galactopyranosyl [NeuAc(2-3)Gal] sequence than one specific for NeuAc(2-6)Gal. Hemagglutination-inhibition assays with N-acetylneuraminyl-alpha(2-3)-lactose [NeuAc(2-3)-lactose] and NeuAc(2-6)-lactose confirmed that the C. pylori hemagglutinin preferentially binds to the NeuAc(2-3)Gal isomer of NeuAc-lactose. Based upon the above-described properties of the C. pylori fibrillar hemagglutinin, we conclude that this antigen should be designated as a putative colonization factor antigen.