title: Population genetic structure of Helicobacter pylori strains from Portuguese-speaking countries.
abstract: BACKGROUND
  The human gastric colonizer Helicobacter pylori is useful to track human migrations given the agreement between the bacterium phylogeographic distribution and human migrations. As Portugal was an African and Brazilian colonizer for over 400 years, we hypothesized that Portuguese isolates were likely genetically closer with those from countries colonized by Portuguese in the past. We aimed to characterize the population structure of several Portuguese-speaking countries, including Portugal, Brazil, Angola, and Cape Verde.
  
  
  METHODS
  We included strains isolated in Portugal from Portuguese and from former Portuguese colonies. These strains were typed by multilocus sequence typing (MLST) for seven housekeeping genes. We also retrieved from Multi Locus Sequence Typing Web site additional housekeeping gene sequences, namely from Angola and Brazil.
  
  
  RESULTS
  We provided evidence that strains from Portuguese belong to hpEurope and that the introgression of hpEurope in non-European countries that speak Portuguese is low, except for Brazil and Cape Verde, where hpEurope accounted for one quarter and one half of the population, respectively. We found genetic similarity for all strains from Portuguese-speaking countries that belong to hpEurope population. Moreover, these strains showed a predominance of ancestral Europe 2 (AE2) over ancestral Europe 1 (AE1), followed by ancestral Africa 1.
  
  
  CONCLUSIONS
  H. pylori is a useful marker even for relative recent human migration events and may become rapidly differentiated from founder populations. H. pylori from Portuguese-speaking countries assigned to hpEurope appears to be a hybrid population resulting from the admixture of AE1, AE2 and ancestral hpAfrica1.
authors.affiliation: Department of Infectious Diseases, National Institute of Health Dr Ricardo Jorge, Lisbon, Portugal.
authors.forename: Mónica
authors.identifier: http://orcid.org/0000-0001-6360-2576
authors.initials: M
authors.lastname: Oleastro
authors.affiliation: Department of Infectious Diseases, National Institute of Health Dr Ricardo Jorge, Lisbon, Portugal.
authors.forename: Raquel
authors.initials: R
authors.lastname: Rocha
authors.affiliation: Host-Pathogen Interactions Unit, Research Institute for Medicines (iMed-ULisboa), Faculty of Pharmacy, Universidade de Lisboa, Lisbon, Portugal.
authors.forename: Filipa F
authors.identifier: http://orcid.org/0000-0003-4635-0105
authors.initials: FF
authors.lastname: Vale
mesh_terms: D000810:Angola; D001938:Brazil; D055726:Cabo Verde; D014644:Genetic Variation; D005828:Genetics, Population; D005838:Genotype; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D063426:Human Migration; D006801:Humans; D058885:Multilocus Sequence Typing; D011174:Portugal
keywords: Helicobacter pylori; Portuguese-speaking countries; coevolution; human evolution; phylogeography; population structure