Synthesis and immunogenicity of a Helicobacter pylori lipopolysaccharide-based conjugate

Helicobacter pylori infection in humans is responsible for the onset of severe gastric disorders and a vaccine would be an improvement over current antibiotic-based treatments. Lipopolysaccharide (LPS; O-chain PS → core → lipid A) is a main H. pylori cell wall component, whose O-chain PS exhibits molecular mimicry and therefore any LPS-based vaccine cannot contain O-chain epitopes. Here, the conjugation of de-lipidated H. pylori O:2 LPS to BSA and its immunogenicity in mice is described. IgG antibodies were observed to recognize the LPSs of representative H. pylori serotypes O:1, O:2 and O:5, and more significantly, the core region of H. pylori. This study showed that a monovalent H. pylori LPS conjugate can elicit antibodies that recognize other serotype-specific H. pylori LPSs and specifically the structurally conserved LPS inner-regions.