Distribution Of BabA2 Gene Of Clinical Strains Of Helicobacter Pylori And Construction Of BabA2 Recombinant Plasmid

Helicobacter pylori (H. pylori) is a Gram-negative spiral-shaped microaerophilic bacterium that colonizes the gastric mucosa of human stomach.. Australian scientists named Warren and Marshall for the first time isolated this bacterium from the human gastric biopsy specimens in 1983. Infection of H. pylori has been implicated as the major cause of gastritis and peptic ulcer, and also appears to be associated with gastric adenocarcinoma and gastric mucosa-associated lymphoid tissue lymphoma. In 1994, H. pylori was declared as a group I carcinogen for gastric cancer by WHO. More than 50% of the world's population is infected with H. pylori and the prevalence of H, pylori infection is 80-90% in countries with low socio-economic status indeed. In most patients (80%) H. pylori does not cause clinical symptoms, but 10-20% of infected patients will develop gastritis and peptic ulcer. A smaller percentage (0.1-4%) of infected patients will develop gastric adenocarcinoma. The research on pathogenesis of H. pylori and how to treat and prevent H. pylori infection properly has been attracting globe's attention more and more.Part one Distribution of babA2 Gene of Clinical Strains of Helicobacter pylori The clinical outcome of H. pylori infection has been attributed to the interaction between bacterial , host and environmental factors. Several putative bacterial virulence factors such as cytotoxin-associated antigen (CagA), vacuolating toxin (VacA) and blood-group antigen-binding adhesin (BabA) have been shown to be related to more severe clinical outcome. BabA is one of the best defined H. pylori adhesins found to date and BabA has been shown to mediate adherence of H, pylori to human Lewis b( a -1,3/4-difucosylated ) blood group antigen on gastric epithelial cells. BabA is encoded by babA2 gene which has recently discovered. The researchers in Germany found that presence of babA2 was significantly associated with duodenal ulcer and adenocarcinoman. There was correlation between babA2 gene and cagA gene.In the present study we investigated the distribution of babA2 gene and cagA gene of 119 H. pylori clinical strains in Zhejiang province. The leiationship between babA2 gene and cagA gene and the relationship between babA2 gene status of isolates and occurrence of gastroduodenal diseases were assessed.1 Materials and methods1. 1 Patients A total of 119 H. pylori-infected patients ( 75 male, 44 female; age range: 20-75yr, median age:43yr ) was enrolled in this study who had undergone upper gastrointestinal endoscopy at the Second Affiliated Hospital of Zhejiang University and the Hospital of Daishan County, Zhejinag province between 2001 and 2002. The patients were classified into those having chronic superficial gastritis(n=49), chronic atrophy gastritis(n=33), peptic ulcer(n=31), gastriccancer(n=6) based on the results of histological examination.1. 2 H. pylori strain A biopsy specimen from the antrum of each patient wasinoculated onto EYC-selective agar plates at 37癈 for 5 days, under 100% humidityand microaerophilic conditions(5% O2, 10% CO2, 85% N2). Organisms wereidentified as H. pylori by colony morphology, Gram staining , rapid urease test andoxidase test.1. 3 PCR for babA2 and cagA1.3.1 PCR primer design babA2 and cagA primers were designed on the basisof the published papers.1. 3. 2 DNA isolation H. pylori genomic DNA was extracted by phenol/chloroformmethod.1. 3. 3 PCR amplification PCR was carried out in a total volume of 50 u1, theamplification program was adjusted for each primer pair.1. 3. 4 PCR product analysis PCR products and DNA ladder were electrophoresedon 1.5% agarose gel for 30 min at 100V and examined undsr UV illumination.1. 4 statistical analysis the x 2 test was used to compare the difference among thegroups. P <0.05 was considered to be significant.2 ResultsOf the 119 clinical isolates, the frequency of babA2 and cagA gene was 84.0%. 96.6%, respectively. There was n...