title: Identification of Helicobacter pylori and the cagA genotype in gastric biopsies using highly sensitive real-time PCR as a new diagnostic tool.
abstract: The CagA protein is one of the virulence factors of Helicobacter pylori, and two major subtypes of CagA have been observed, the Western and East Asian type. CagA is injected from the bacteria into gastric epithelial cells, undergoes tyrosine phosphorylation, and binds to Src homology 2 domain-containing protein-tyrosine phosphatase SHP-2. The East Asian type CagA binds to SHP-2 more strongly than the Western type CagA. Here, we tried to distinguish the CagA type by highly sensitive real-time PCR with the objective of establishing a system to detect H. pylori and CagA subtypes from gastric biopsies. We designed primers and probe sets for Western or East Asian-cagA at Western-specific or East Asian-specific sequence regions, respectively, and H. pylori 16S rRNA. We could detect the H. pylori 16S rRNA gene, Western and East Asian-cagA gene from DNA of gastric biopsies. The sensitivity and specificity for H. pylori infection was 100% in this system. In Thai patients, 87.8% (36/41) were cagA-positive; 26.8% (11/41) were Western-cagA positive and 53.7% (22/41) were East Asian-cagA positive, while 7.3% (3/41) reacted with both types of cagA. These results suggest that this real-time PCR system provides a highly sensitive assessment of CagA type as a new diagnostic tool for the pathogenicity of H. pylori infection.
authors.affiliation: Second Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Matsuoka-cho, Yoshida-gun, Fukui 910-1193, Japan.
authors.forename: Shiho
authors.initials: S
authors.lastname: Yamazaki
authors.forename: Shunji
authors.initials: S
authors.lastname: Kato
authors.forename: Norio
authors.initials: N
authors.lastname: Matsukura
authors.forename: Masahiro
authors.initials: M
authors.lastname: Ohtani
authors.forename: Yoshiyuki
authors.initials: Y
authors.lastname: Ito
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Suto
authors.forename: Yukinao
authors.initials: Y
authors.lastname: Yamazaki
authors.forename: Akiyo
authors.initials: A
authors.lastname: Yamakawa
authors.forename: Shinkan
authors.initials: S
authors.lastname: Tokudome
authors.forename: Hideaki
authors.initials: H
authors.lastname: Higashi
authors.forename: Masanori
authors.initials: M
authors.lastname: Hatakeyama
authors.forename: Takeshi
authors.initials: T
authors.lastname: Azuma
mesh_terms: D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000235:genetics / Q000302:isolation & purification*; D001426:Bacterial Proteins / Q000235:genetics / Q000302:isolation & purification*; D001483:Base Sequence; D001706:Biopsy; D005260:Female; D005753:Gastric Mucosa / Q000382:microbiology*; D005798:Genes, Bacterial; D016481:Helicobacter Infections / Q000175:diagnosis* / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics / Q000302:isolation & purification*; D006801:Humans; D008297:Male; D008875:Middle Aged; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction / Q000379:methods*; D011110:Polymorphism, Genetic; D012329:RNA, Bacterial / Q000032:analysis; D012336:RNA, Ribosomal, 16S / Q000032:analysis; D012680:Sensitivity and Specificity; D013785:Thailand
chemical_list: D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; C080866:cagA protein, Helicobacter pylori