Helicobacter pylori outer membrane protein, HomC, shows geographic dependent polymorphism that is influenced by the Bab family

The array of outer membrane proteins (OMPs) found in Helicobacter pylori provides a crucial component for persistent colonization within the gastric niche. Not only does H. pylori harbor a wide number of OMPs, but these OMPs often vary across strains; this likely contributes to immune evasion, adaptation during long term colonization, and potentially differential disease progression. Previous work from our group described OMP differences among the Bab family (babA, babB, and babC) and Hom family (homA and homB) from 80 American H. pylori clinical isolates (AH) and 80 South Korean H. pylori clinical isolates (KH). In the current study, we expanded our investigation to include the less well characterized Hom family member, HomC. Overall, we identified and genotyped three homC variants: homC^S, homC^L, and homC^M, in both populations. Similar to other polymorphic genes, the KH group showed less overall diversity, with 97.5% of strains harboring homC^L. In contrast, a more heterogeneous profile was observed in strains derived from an American population; we found nearly equal distribution of homC^S and homC^L. Further analysis of the AH group identified associations between homC polymorphism and bab genotype; in AH strains, there was a significant association between homC^L and carriage of babA at locus A. Since babA is an important virulence factor for the development of severe gastric disease, these data may suggest that homC polymorphism plays a role in H. pylori pathogenesis.