title: Expansion of European vacA and cagA alleles to East-Asian Helicobacter pylori strains in Cambodia.
abstract: Helicobacter pylori infection is associated with gastric cancer (GC). The highest incidence rates have been described in Asia, but regional variations exist that do not match the distribution of infection prevalence rates. The aim of the study was to examine the possible contribution of H. pylori virulence factors to geographic differences in the incidence of GC across East and Southeast Asia. We studied 66 isolates from Cambodian patients that had previously been assigned to two genetic populations based on sequences of seven housekeeping genes, namely hpEurope (n = 34, 51.5%) and hpEastAsia, subpopulation hspEAsia (n = 32, 48.5%). These strains were characterized with respect to vacA polymorphism and cagA status by PCR, and the CagA C-terminal region was sequenced. We also sequenced the complete cagA gene from 10 hpEurope and 10 hspEAsia strains chosen at random. The cagA gene was present in 92.4% of the 66 isolates and was mainly of Western type (n = 36, 59.0%). hspEAsia strains carrying East-Asian CagA and the m1-type vacA allele (15.2%) were less frequent among the 66 Cambodian isolates than reported in East Asian countries, a finding that might partly explain the intermediate incidence of GC in Cambodia, and by extension, in Southeast Asia (except for Vietnam). The observed high prevalence of s1a alleles (34.4%) and Western CagA (28.1%) among hspEAsia strains indicates frequent introgression of European vacA and cagA alleles into East Asian H. pylori strains. This expansion might have severe consequences for individual disease outcome.
authors.affiliation: Unité de Bactériologie Médicale et Environnementale, Institut Pasteur, 36 Avenue Pasteur, BP 220, Dakar, Senegal. sbreurec@pasteur.sn
authors.forename: Sebastien
authors.initials: S
authors.lastname: Breurec
authors.forename: Bertrand
authors.initials: B
authors.lastname: Guillard
authors.forename: Sopheak
authors.initials: S
authors.lastname: Hem
authors.forename: Konstantinos S
authors.initials: KS
authors.lastname: Papadakos
authors.forename: Sylvain
authors.initials: S
authors.lastname: Brisse
authors.forename: Michel
authors.initials: M
authors.lastname: Huerre
authors.forename: Didier
authors.initials: D
authors.lastname: Monchy
authors.forename: Chakravuth
authors.initials: C
authors.lastname: Oung
authors.forename: Dionyssios N
authors.initials: DN
authors.lastname: Sgouras
authors.forename: Tek Sreng
authors.initials: TS
authors.lastname: Tan
authors.forename: Jean-Michel
authors.initials: JM
authors.lastname: Thiberge
authors.forename: Sirenda
authors.initials: S
authors.lastname: Vong
authors.forename: Josette
authors.initials: J
authors.lastname: Raymond
authors.forename: Bodo
authors.initials: B
authors.lastname: Linz
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000483:Alleles; D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D002160:Cambodia / Q000453:epidemiology; D004641:Emigration and Immigration; D005060:Europe / Q000453:epidemiology; D005202:Asia, Eastern / Q000453:epidemiology; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology / Q000473:pathology; D014644:Genetic Variation; D016481:Helicobacter Infections / Q000150:complications / Q000453:epidemiology; D016480:Helicobacter pylori / Q000235:genetics* / Q000472:pathogenicity; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D010802:Phylogeny; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D013274:Stomach Neoplasms / Q000453:epidemiology / Q000209:etiology / Q000382:microbiology; D055815:Young Adult
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori