title: Analysis of hopQ alleles in East Asian and Western strains of Helicobacter pylori.
abstract: Helicobacter pylori hopQ (omp27) alleles exhibit a high level of genetic diversity, and certain hopQ genotypes have been associated with an increased risk for peptic ulcer disease. In this study, we analyzed hopQ alleles in H. pylori strains from East Asia and the United States. Phylogenetic analysis indicated the presence of two highly divergent families of hopQ alleles, without evidence of extensive recombination. Type I hopQ alleles from Western and Asian H. pylori strains were similar, and markedly different from type II hopQ alleles. Analyses of synonymous and non-synonymous nucleotide substitutions suggested that there is a positive selection for HopQ amino acid diversity. Type II hopQ alleles were identified commonly in Western H. pylori strains, but rarely in East Asian strains. Nearly all of the East Asian strains analyzed were cagA-positive and contained type I hopQ alleles. Geographic variation in the genetic characteristics of H. pylori strains may be a factor contributing to geographic variation in gastric cancer incidence.
authors.affiliation: Department of Medicine, Division of Infectious Diseases, A2200 Medical Center North, Vanderbilt University School of Medicine, Nashville, TN 37232, USA.
authors.forename: Ping
authors.initials: P
authors.lastname: Cao
authors.forename: Kerry Jo
authors.initials: KJ
authors.lastname: Lee
authors.forename: Martin J
authors.initials: MJ
authors.lastname: Blaser
authors.forename: Timothy L
authors.initials: TL
authors.lastname: Cover
mesh_terms: D000483:Alleles; D019943:Amino Acid Substitution; D000942:Antigens, Bacterial / Q000235:genetics; D001425:Bacterial Outer Membrane Proteins / Q000737:chemistry / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005202:Asia, Eastern; D014644:Genetic Variation; D005843:Geography; D016481:Helicobacter Infections / Q000382:microbiology*; D016480:Helicobacter pylori / Q000145:classification* / Q000235:genetics* / Q000302:isolation & purification; D008969:Molecular Sequence Data; D010802:Phylogeny; D017422:Sequence Analysis, DNA; D012689:Sequence Homology, Nucleic Acid; D014481:United States
chemical_list: D000942:Antigens, Bacterial; D001425:Bacterial Outer Membrane Proteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C080866:cagA protein, Helicobacter pylori