The Correlation Between Virulence Genotypes Of Helicobacter Pylori And Gastric Cancer

Objetive: This study aimed to detect the prevalence of virulence genotypes of Helicobacter pylori (Hp) in Qing-Dao, China and to investigate the correlation between virulence genotypes and gastric cancer.Methods:52isolates of Hp were cultured from gastric biopsies obtained from31patients with chronic gastritis and21with gastric cancer. The virulence genes, cagA, iceAl, vac A s, i and m regions were amplified using PCR. The correlation between virulence genotypes and gastric cancer were studied. The cagA5’region was amplified in all isolates,21of them were sequenced. The multiple-sequence alignment and phylogenetic analysis were carried out to analyse these regions.Result:The prevalence of cagA、 vac A sl/il/m1、 vacA s1/i1/m2and iceA1in52Hp isolates were92.3%(48/52),48.1%(25/52),48.1%(25/52),90.4%(47/52), respectively. All the gastric cancer isolates were cagA(+) vacA sl/il(+), and the positive rates of vacA m1、 vacA m2and iceAl in gastric cancer group were47.6%(10/21),52.4%(11/21),95.2%(20/21), respectively. There were no statistically significant in the differences of the positive rates of cagA、 vacA s、 vacA i、 vac A m and iceAl between gastric cancer group and gastritis group (p>0.05). The phylogenetic analysis of the cagA5’region showed that all the21isolates belonged to East Asia population. Although the specific sequence close to5’end of cagA, A AT AA GAT A, influenced the expression of CagA in strains from Europe, it did not exist in the isolates from East Asia by the analysis of multiple-sequence alignment. The phylogenetic analysis revealed that21clinical isolates can be divided into two groups. There was a statistically difference between the two groups in the proportion of gastric cancer isolates (70%vs27.3%, P<0.05).Conclusions:cagA, vacA sl/il/ml, vacA s1/i1/m2and iceA1positive genotypes were most prevalent in Hp isolated from Qing-Dao, China. It appeared that there was no significant correlation between these virulence genotypes and the generation of gastric cancer in Qing-Dao, China. However, strains from gastric cancer tended to be clustered together.