Population genetic structure and isolation by distance of Helicobacter pylori in Senegal and Madagascar.
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.
Department of Biochemistry and Molecular Biology, Pennsylvania State University, University Park, Pennsylvania, United States of America.
Bodo
B
Linz
Laboratoire d'Anatomie et de Cytologie Pathologiques, Institut Pasteur, Antananarivo, Madagascar.
Clairette Romaine Raharisolo
CR
Vololonantenainab
Laboratoire de Biologie Médicale, Institut Pasteur, Dakar, Senegal.
Abdoulaye
A
Seck
Centre de Biologie Clinique, Institut Pasteur, Antananarivo, Madagascar.
Jean-François
JF
Carod
Centre Hospitalier Le Dantec, Département de Gastro-entérologie, Dakar, Senegal.
Daouda
D
Dia
Laboratoire de Biologie Médicale, Institut Pasteur, Dakar, Senegal ; Laboratoire de Bactériologie expérimentale, Institut Pasteur, Antananarivo, Madagascar.
Benoit
B
Garin
Centre Hospitalier Universitaire Joseph Ravoahangy Befelatanana, Département de Gastro-entérologie, Antananarivo, Madagascar.
Rado Manitrala
RM
Ramanampamonjy
Plate-forme Génotypage des Pathogènes et Santé Publique, Institut Pasteur, Paris, France.
Jean-Michel
JM
Thiberge
Unité Postulante Pathogenèse de Helicobacter, Institut Pasteur, Paris, France.
Josette
J
Raymond
Laboratoire de Biologie Médicale, Institut Pasteur, Dakar, Senegal ; Institut Pasteur, Laboratoire de Biologie médicale, Bangui, République Centrafricaine.
Sebastien
S
Breurec
D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044383:Black People / Q000235:genetics; D014644:Genetic Variation / Q000235:genetics; D005828:Genetics, Population / Q000379:methods; D005843:Geography / Q000379:methods; D016481:Helicobacter Infections / Q000235:genetics / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics* / Q000302:isolation & purification*; D063426:Human Migration; D006801:Humans; D008270:Madagascar; D008875:Middle Aged; D010802:Phylogeny; D044382:Population Groups / Q000235:genetics; D012675:Senegal; D055815:Young Adult