Frick, J.; Sonnert, N. D.; Snow, J.; Overly, M.; Yang, H.; Stoppler, M. N.; Ring, A. M.; Ernst, R. K.; Palm, N.; Salama, N. R.

Helicobacter pylori, the primary etiological agent of gastric cancer, requires chronic infection to promote severe disease. Throughout colonization, the bacteria accumulate genetic variation, which can reshape the interaction between host and pathogen. In this study, we probed adherence as one important characteristic of this relationship. We leveraged a panel of H. pylori strains, representing both inter- and intra-host diversity, and BASEHIT, a comprehensive barcoded yeast display library of the human exoproteome, to evaluate the human exoprotein binding characteristics of H. pylori. We identified a set of lineage-correlated binding phenotypes and a set of polymorphic cell surface- associated loci that we predict to govern heterogeneous binding. We also identified a general increase in gastric tissue adherence during mouse passage and structural modifications in the O-antigen component lipopolysaccharide. Subsequent sequence analyses identified C-terminal repeat length reduction in either futB or glycosyltransferase family 25 galactose transferases as sufficient to alter lipopolysaccharide. Shorter repeat variants were favored during both acute and chronic colonization and conferred a colonization advantage in coinfection. Our data indicate that shorter enzymes, and the resulting shorter O-antigen repeats, are favored during infection. We hypothesize that repeat length polymorphisms modulate enzyme efficiency and disrupt the balance of competing reactions required for O-antigen synthesis.