Insights from the redefinition of Helicobacter pylori lipopolysaccharide O-antigen and core-oligosaccharide domains.

H. pylori is a Gram-negative extracellular bacterium, first discovered by the Australian physicians Barry Marshall and Robin Warren in 1982, that colonises the human stomach mucosa. It is the leading cause of peptic ulcer and commonly infects humans worldwide with prevalence as high as 90% in some countries. H. pylori infection usually results in asymptomatic chronic gastritis, however 10-15% of cases develop duodenal or gastric ulcers and 1-3% develop stomach cancer. Infection is generally acquired during childhood and persists for life in the absence of antibiotic treatment. H. pylori has had a long period of co-evolution with humans, going back to human migration out of Africa. This prolonged relationship is likely to have shaped the overall host-pathogen interactions and repertoire of virulence strategies which H. pylori employs to establish robust colonisation, escape immune responses and persist in the gastric niche. In this regard, H. pylori lipopolysaccharide (LPS) is a key surface determinant in establishing colonisation and persistence via host mimicry and resistance to cationic antimicrobial peptides. Thus, elucidation of the H. pylori LPS structure and corresponding biosynthetic pathway represents an important step towards better understanding of H. pylori pathogenesis and the development of novel therapeutic interventions.