ABSTRACT
Genetic diversity within the cag pathogenicity island (PAI) of Helicobacter pylori may have a modifying effect on the pathogenic potential of the infecting strain. The genetic structure of the cag PAI was examined in Japanese isolates. The composition and nucleotide sequences of the cag PAI were quite similar among strains; however, diversity between 2 cag genes (virB10 and cagA) was observed. The variety in the number of repetition of the 5-amino acid sequence R1 (EPIYA) in the 3' region of the cagA gene was identified. The frequencies of the genotypes that contained >4 R1 sequences were significantly higher in atrophic gastritis-causing strains than in duodenal ulcer-causing strains. One-third of strains with >4 R1 sequences were gastric cancer-causing strains. Although the cag PAI is conserved in H. pylori isolates in Japan, H. pylori infection with the cagA genotype with >4 R1 sequences may correlate with the pathogenesis of atrophic gastritis and gastric cancer.
Subject(s)
Antigens, Bacterial , Bacterial Proteins/genetics , Gastritis, Atrophic/microbiology , Genetic Variation , Helicobacter Infections/complications , Helicobacter pylori/pathogenicity , Stomach Neoplasms/microbiology , Amino Acid Sequence , Bacterial Proteins/chemistry , Bacterial Proteins/metabolism , Disease Progression , Female , Gastrointestinal Diseases/microbiology , Helicobacter Infections/microbiology , Helicobacter pylori/genetics , Humans , Japan , Male , Middle Aged , Molecular Sequence Data , Sequence Alignment , Sequence Analysis, DNA , VirulenceABSTRACT
It has been reported that H. pylori-containing cagE was associated with duodenal ulcer. The aims of the present study were to clarify the association between the cagE gene and clinical outcome and to analyze the relationship between the cagE gene and two other virulence factors--cagA and vacA--in two areas in Japan (Fukui and Okinawa) where the prevalence of duodenal ulcer and gastric cancer risk are quite different. Eighty of 81 isolates possessed the cagE gene, and all isolates possessed the cagA gene. The vacA genotype s1c/ml was a major genotype in both areas in Japan. There was no significant association between cagE, cagA status, or vacA genotype and clinical outcome. Phylogenetic analysis of the cagE gene indicated that most Japanese isolates formed a different cluster from strains isolated in the West with an association with the vacA genotype. In conclusion, the strains with cagE, cagA, and the s1c/ml genotype of vacA are predominant in Japan regardless of clinical outcome and construct a different phylogenetic cluster from those in the West.
