A new subtype of 3' region of cagA gene in Helicobacter pylori strains isolated from Zhejiang Province in China.
OBJECTIVE
To isolate the subtypes of 3' region of cagA gene in Helicobacter pylori (H pylori) strains from Zhejiang Province in China and to investigate their relations to H pylori-associated gastroduodenal diseases.


METHODS
One hundred and thirty-seven H pylori clinical strains were isolated from the gastric mucosa specimens of 74 patients with chronic gastritis, 61 with peptic ulceration, and 2 with gastric cancer. Bacterial genomic DNA was extracted and 3' region of cagA gene was amplified by polymerase chain reaction (PCR). Subtypes of 3' region of cagA gene were determined by the size of PCR amplified segments. The sequences of the subtypes were analyzed by PCR-based sequencing.


RESULTS
Of the 137 H pylori isolates from Zhejiang Province, 132 (96.4%) yielded PCR products that could be classified into three groups of subtypes, named as subtypes I, II, and III according to their sizes. The sizes of subtypes I, II, and III were 648-650 bp, 705-707 bp, and 815 bp, respectively. Among the 132 cagA-positive H pylori strains, 123 (93.2%) belonged to the group of subtype I, 6 (4.5%) presented subtype II, 1 (0.8%) was subtype III, and 2 (1.5%) presented subtypes I and III both. The primary structure of subtype I was composed of 3 repeats of R1, 1 repeat of R2 and 1 repeat of R3. Subtype II possessing 4 repeats of R1, 2 repeats of R2 and 1 repeat of R3 was a newly found type of 3' region of cagA gene which had not been reported before. The primary structure of subtype III consisted of 4 repeats of R1, 1 repeat of R2 and 2 repeats of R3. Comparison of the sequences of subtype I strains with the corresponding sequences deposited in GenBank, showed a similarity of 95.0% (94.0-96.1%) for nucleotide sequences and 95.9% (94.9-97.4%) for deduced amino acid sequences. Comparison of the sequences of subtype III strains with the corresponding sequences deposited in GenBank, showed a similarity of 93.9% (90.8-96.9%) for nucleotide sequences and 93.2% (90.2-96.2%) for deduced amino acid sequences. Among subtype II strains, the nucleotide and deduced amino acid sequences showed a similarity of 95.2% (94.1-96.5%) and 96.4% (93.8-97.9%), respectively. There were no statistical differences in the distribution of subtypes of 3' region of cagA gene among different H pylori-associated gastroduodenal diseases (chi(2) = 11.544, P>0.05).


CONCLUSIONS
There are three subtypes (I, II, and III) of 3' region of cagA gene in H pylori strains isolated from Zhejiang Province, and subtypeIis predominant. Subtype II is a newly found subtype of 3' region of cagA gene. The result of this study does not support the view that the subtypes of 3' region of cagA gene in H pylori isolated from Zhejiang Province are correlated with the clinical outcomes of H pylori infection.
Tao
Ran
R
Department of Medical Microbiology and Parasitology, Zhejiang University School of Medicine, 353 Yan'an Road, Hangzhou 310006, Zhejiang Province, China.
Fang
Ping-Chu
PC
Liu
Hai-Yan
HY
Jiang
Yun-Shui
YS
Chen
Jing
J
D000293:Adolescent; D000328:Adult; D000368:Aged; D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000737:chemistry / Q000235:genetics*; D001426:Bacterial Proteins / Q000737:chemistry / Q000235:genetics*; D002681:China; D005260:Female; D005756:Gastritis / Q000382:microbiology; D016481:Helicobacter Infections / 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; D017434:Protein Structure, Tertiary
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; C080866:cagA protein, Helicobacter pylori