Identification of Helicobacter pylori and the cagA genotype in gastric biopsies using highly sensitive real-time PCR as a new diagnostic tool.
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.
Yamazaki
Shiho
S
Second Department of Internal Medicine, Faculty of Medical Sciences, University of Fukui, Matsuoka-cho, Yoshida-gun, Fukui 910-1193, Japan.
Kato
Shunji
S
Matsukura
Norio
N
Ohtani
Masahiro
M
Ito
Yoshiyuki
Y
Suto
Hiroyuki
H
Yamazaki
Yukinao
Y
Yamakawa
Akiyo
A
Tokudome
Shinkan
S
Higashi
Hideaki
H
Hatakeyama
Masanori
M
Azuma
Takeshi
T
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
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D012329:RNA, Bacterial; D012336:RNA, Ribosomal, 16S; C080866:cagA protein, Helicobacter pylori