Characterization of East Asian and African Genotypes among Helicobacter pylori Strains Isolated from Different Human Populations - Abstract
Background: Helicobacter pylori, a genetically diverse bacterium has shown to have geographic specific genotypes. This may be relevant since there are also differences in clinical outcome among H. pylori infected patients from different geographical origin.
Aim: The aim of this study was to identify a true marker for African origin based on the sequence of a housekeeping gene (hspA) and if African origin could be defined, to establish possible differences in virulence attributes between African and non-African strains.
Material and methods: The hspA gene was analyzed by PCR amplification and direct sequencing of the PCR products in 163 strains from patients with diverse ethnic origin. To asses for virulence, the cag pathogenic island (cag PAI) was analyzed by three different kinds of PCR amplifications in the same 163 strains.
Results: The hspA gene showed to be very informative for differentiating strains of diverse ethnic origin. In particular, different phenotypes defining
African and East Asian origin were found when amino acid sequences were compared. In addition, a marker for East Asian origin was found upstream of the hspA gene. Based on the presence of cag PAI, African American strains together with East Asian strains were shown to be the most virulent. East Asian strains amplified lower molecular weight PCR products than African American strains at the cag PAI level. Whether this is relevant for the functionality of the cag PAI should be further explored.
Conclusion: Highly specific markers that define H. pylori strains of African and East-Asian origins were identified. However, no differences in virulence attributes were observed between those strains.