Detection Of The Helicobacter Pylori IceA1 And BabA2 Genotype And Its Clinical Association

Helicobacter pylori(H.pylori,Hp) is one of the most major factors inducing pathological changes in human gastric mucosa.It can cause chronic gastritis and gastroduodenal ulcer,and is correlated with gastric cancer.About half of people in the world were infected with it,but only part of them experience clinical diseases.The reason might be the different pathogenicity of H.pylori.Many results from epidemiological investigation showed that the cagA,vacA,iceA and babA genes are the major virulence factors of H.pylori and are highly correlated with the development of gastroduodenal ulcer and gastric cancer.However,the result is not the same between the west and the east,and varies in different districts of China.The research about the genes cagA and vacA is somewhat deep going,while there is still dissension on the research results of iceA and babA.The iceA gene is a newly found gene associated with the virulence of H.pylori.Expression of iceA can be induced by the touch between H.pylori and gastric epithelial cell.There are two alleles,iceA1 and iceA2,which is located in different strands.The protein,blood group antigen-binding adhesion(babA),is one of the most understood adhesin of H.pylori.It can bind with the fucose glycosylated blood group antigen Lewisb on the surface of the gastric epithelial cell,and mediate the adhesion between H.pylori and gastric epithelial cell and reinforce the setting ability of H.pylori.babA has two kinds of allele,babA1 and babA2,while only babA2 is bio-active.We isolated H.pylori strains from 70 patients,among which 30 cases were diagnosed as chronic gastritis,26 cases as gastroduodenal ulcer and 14 cases as gastric cancer.The genome DNA of H.pylori was extracted to amplify the genes by PCR.The primers were designed according to the known sequence of gene iceA1(No.AF 459446.1) and gene babA2(No. AF 033654.1),respectively.Then we identify the products,compare their structural characteristics and analyse the distribution of gene iceA1 and babA2 in different types of gastroduodenal diseases and the relationship between certain genotype and disease.The results showed that the general positive rate of iceA1 is 68.6%, and that of babA2 is 65.7%.85.7%(12/14) of the patients diagnosed as gastric cancer,60%(18/30) of the patients with chronic gastritis and 69.2%(18/26) of those with gastrodudenal ulcer were infected by iceA1 positive H.pylori.While infection rate of babA2 positive H.pylori is 66.7%(8/14) in gastric cancer,63.3%(19/30) in chronic gastritis and 73.1%(19/26) in gastrodudenal ulcer.Primary analysis on the structural characteristics of iceA1 indicates that structure of gene iceA1 isolated from H.pylori in Zhenjiang district has some specific characters.The reading frame of gene iceA1 has three translation initiation sites.Majority of the strands from Zhenjiang initiate translation from the third site and produce smaller protein.While most Japanese strands begin translation from the second sites and the western strands begin from the first or second site.This may cause the difference of virulence among different strand.The positive rate of iceA1 in H.pylori isolated from patients in Zhenjiang is consistent with the published reports from other Asian countries.The positive rate of iceA1 in patients with gastric cancer is higher than that in patients with chronic gastritis or gastrodudenal ulcer. The positive rate of babA2 is higher than that of Western countries,but is not associated with the occurrence of gastric cancer,gastrodudenal ulcer or chronic gastritis.