Population Genetic Structure and Isolation by Distance of Helicobacter pylori in Senegal and Madagascar

Abstract

Helicobacter pylori has probably infected the human stomach since our origins and subsequently diversified in parallel with their human hosts. The genetic population history of H. pylori can therefore be used as a marker for human migration. We analysed seven housekeeping gene sequences of H. pylori strains isolated from 78 Senegalese and 24 Malagasy patients and compared them with the sequences of strains from other geographical locations. H. pylori from Senegal and Madagascar can be placed in the previously described HpAfrica1 genetic population, subpopulations hspWAfrica and hspSAfrica, respectively. These 2 subpopulations correspond to the distribution of Niger-Congo speakers in West and most of subequatorial Africa (due to Bantu migrations), respectively. H. pylori appears as a single population in Senegal, indicating a long common history between ethnicities as well as frequent local admixtures. The lack of differentiation between these isolates and an increasing genetic differentiation with geographical distance between sampling locations in Africa was evidence for genetic isolation by distance. The Austronesian expansion that started from Taiwan 5000 years ago dispersed one of the 10 subgroups of the Austronesian language family via insular Southeast Asia into the Pacific and Madagascar, and hspMaori is a marker for the entire Austronesian expansion. Strain competition and replacement of hspMaori by hpAfrica1 strains from Bantu migrants are the probable reasons for the presence of hspSAfrica strains in Malagasy of Southeast Asian descent. hpAfrica1 strains appear to be generalist strains that have the necessary genetic diversity to efficiently colonise a wide host spectrum.

Population genetic structure of Helicobacter pylori strains from Portuguese‐speaking countries

“…Pair-wise F ST values and the analysis of molecular variance (AMOVA) were calculated in ARLEQUIM 24 using Kimura twoparameter model as previously described by others [25][26][27] for the strains belonging to either hpAfrica1 or hpEurope. The significance of the pair-wise F ST values was estimated by running 10 000 permutations, assuming no differences between the populations.…”

“…Among the 10 hpAfrica1 strains isolated in Portugal with African ancestry, only two were hspSAfrica1 (one from Angola and one from Mozambique), and the other eight were hspWAfrica (Table 1).The pair-wise F ST is a measure of genetic differentiation between populations. An F ST of zero indicates no divergence and free recombination between two populations, and an F ST of 1 indicates complete isolation of populations 27. The pair-wise F ST values from Portuguesespeaking countries assigned hpAfrica1 were significantly (F ST P value ID used by H. pylori pubMLST.…”

“…An F ST of zero indicates no divergence and free recombination between two populations, and an F ST of 1 indicates complete isolation of populations 27. Thus, the hpAfrica1 isolates from Portuguese-speaking countries do not form a new subpopulation of hpAfrica1.…”

Prostate Specific Antigen and Prostate Cancer in Chinese Men Undergoing Initial Prostate Biopsies Compared with Western Cohorts

“…One possible explanation for the reduced incidence of PCa in Asia is dietary: traditional East Asian food, such as high isoflavones 16 and green tea 17 , has been linked to a lower incidence rate of PCa. Moreover, several studies have reported that the incidence of PCa in Asian immigrants to North America 18-20 and European countries 21-23 is substantially higher than their home countries, again suggesting a dietary explanation. Previous reports suggest that serum levels of total and bioavailable testosterone does not differ between the Chinese and Caucasians 24, 25 .…”

Population Genetic Analyses of Helicobacter pylori Isolates from Gambian Adults and Children

“…To determine the relatedness of Gambian H. pylori to previously studied strains from elsewhere, 246 strains representing H. pylori 's global diversity were selected from the public MLST data base ( Table 1 ). This data set included all strains previously published from West Africa [22] , [25] , [30] . Reconstruction of a global phylogeny was carried out using neighbor-joining as described above.…”