Immunological Exploration of Helicobacter pylori Serotype O2 O-Antigen by Using a Synthetic Glycan Library

Helicobacter pylori (H. pylori) infection is a threat to human health. The lipopolysaccharide (LPS) O-antigen holds promise for developing vaccines. It is meaningful to explore the immunological activity of oligosaccharides with different lengths and frameshifts for antigen development. Herein, a glycan library of H. pylori O2 O-antigen containing eight fragments is constructed. After screening with anti-H. pylori O2 LPS sera and patients' sera by glycan microarray, the disaccharide HPO2G-2b and trisaccharide HPO2G-3a show strong antigenicity and then are separately conjugated with carrier protein CRM197. Both glycoconjugates elicit a robust immunoglobulin G (IgG) immune response in rabbits. The anti-HPO2G-3a IgG antibodies possess a much stronger binding affinity with the LPS and bacteria of H. pylori O2 than the anti-HPO2G-2b IgG antibodies. There is no cross-reaction between both sera IgG antibodies with LPS and bacteria of H. pylori O1, O6, and E. coli. The results demonstrate the trisaccharide HPO2G-3a is a promising candidate for H. pylori vaccine development.