Previous data has shown that gene fragment sequences from Helicobacter pylori differ according to continent of origin.
In this study, an international team of researchers used a population genetic tool to analyze a large global sample of H. pylori isolates. They sought to define modern populations and reconstruct their ancestral sources.
The team identified 4 modern populations on the basis of their current distributions. These were labeled hpAfrica1, hpAfrica2, hpEastAsia and hpEurope. Further analyses split hpEastAsia into 3 subpopulations, and hpAfrica1 into 2. These data confirm geographical subdivisions.
The researchers were unsuccessful in identifying subpopulations within the population from Europe, possibly reflecting the complex history of European migration.
|4 modern populations were identified on the basis of their current distributions.|
The team's definition of 7 modern populations and subpopulations provides a solid basis for deducing the global patterns of the spread of H. pylori with their human hosts.
Spread can be attributed to human migratory fluxes such as the prehistoric colonization of Polynesia and the Americas.
The team also identified 5 ancestral populations of H. pylori using a linkage model.
Knowledge of the ancestral gene pools allows inferences about gene flow between populations and known human migrations can help explain the spread of H. pylori.
The researchers also determined that the time elapsed since modern human migration is too short for distinctions between multiple bacterial populations to become blurred.
Dr Daniel Falush's team concluded, "High sequence diversity in H. pylori allows recognition of distinct populations after centuries of coexistence in individual geographical locations".
"Thus, analysis of H. pylori populations could help resolve details of human migration."