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

Comprehensive Summary 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.