Association of virulent genotypes and phylogenetic origins of Helicobacter pylori with gastric cancer.
OBJECTIVE
To investigate the association between the genotypes, sequence variations and phylogenetic origins of strains of Helicobacter pylori with gastric cancer in Chinese patients.


METHODS
Strains of H. pylori were isolated from patients with chronic gastritis and gastric cancer. Genotypes of the cagA and vacA genes were determined using polymerase chain reaction. Sequence analysis was used to detect variations in the 3' and 5' regions of cagA, and to detect known polymorphisms in cagE. A phylogenetic tree was constructed based on the analysis of seven housekeeping genes.


RESULTS
A total of 67 strains of H. pylori were analysed. Nearly all strains of H. pylori carried cagA (65/67; 97.0%), an East Asia type of the cagA 3' region (63/65; 96.9%) and the vacA intermediate (i)1 genotype (65/67; 97.0%). None of the H. pylori strains examined had sequence variations in the 5' region of cagA or cagE. Phylogenetic analyses, however, revealed that strains of H. pylori from gastric cancer tended to cluster together.


CONCLUSIONS
Virulent strains of H. pylori were highly prevalent, but virulent genotypes of H. pylori associated with gastric cancer were not detected in this geographical region.
Central Laboratories, Qingdao Municipal Hospital, Qingdao, Shandong Province, China.
Lili
L
Wang
Central Laboratories, Qingdao Municipal Hospital, Qingdao, Shandong Province, China.
Shuhui
S
Zhan
Department of Stomatology, Qingdao Municipal Hospital, Qingdao, Shandong Province, China.
Jianhua
J
Zhou
Central Laboratories, Qingdao Municipal Hospital, Qingdao, Shandong Province, China.
Jingjing
J
Huang
Central Laboratories, Qingdao Municipal Hospital, Qingdao, Shandong Province, China.
Xinjuan
X
Yu
Central Laboratories, Qingdao Municipal Hospital, Qingdao, Shandong Province, China.
Kaixin
K
Dong
Central Laboratories, Qingdao Municipal Hospital, Qingdao, Shandong Province, China Department of Gastroenterology, Qingdao Municipal Hospital, Qingdao, Shandong Province, China jiangacer@126.com.
Quanjiang
Q
Dong
D000942:Antigens, Bacterial / Q000235:genetics*; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D002681:China; D004269:DNA, Bacterial / Q000235:genetics; D005756:Gastritis / Q000382:microbiology*; D005838:Genotype; D016481:Helicobacter Infections / Q000382:microbiology; D016480:Helicobacter pylori / Q000235:genetics* / Q000302:isolation & purification / Q000472:pathogenicity; D006801:Humans; D008875:Middle Aged; D010802:Phylogeny; D020641:Polymorphism, Single Nucleotide / Q000235:genetics; D017422:Sequence Analysis, DNA; D013274:Stomach Neoplasms / Q000382:microbiology*
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C074689:VacA protein, Helicobacter pylori; C080866:cagA protein, Helicobacter pylori
Helicobacter pylori; gastric cancer; genotypes; phylogenetic analysis; virulence