| Helicobacter pylori (H.pylori) is one of the most common bacterial pathogens of human beings. Many studies have shown that it can cause chronic type B gastritis and peptic ulcers, and it is also related to the gastric carcinoma and the gastric mucosa-associated lymphoid tissue (MALT) lymphomas. In 1994, World Health Organization (WHO) classified H.pylori as a definite (class I) carcinogen. Centers for Disease Control and Prevention (CDC) have classified H.pylori infectious diseases as one of the new emerging infectious diseases.The infection rate of H.pylori is almost 60% in the population. However, not all the infected individuals would have gastrointestinal diseases. 20-30% of the infected persons are asymptomatic, 50% may have gastritis, 10-15% may have pepticulcers, a proportion of them may develop gastric carcinoma. This suggests that different genotypes of H.pylori might cause different diseases. The mechanism of pathogenic diversity and the mode of transmission are not clear at present. The pancity of knowledge in these areas is in part due to the lack of a reliable universal classification method for H.pylori.Because H.pylori is one kind of bacteria which have similar appearance, but have high genetic diversity. In this study, PCR-RFLP technique was used to classify 46 clinical isolates of H.pylori (25 ulcerous strains and 21 non-ulcerous strains). The relationships between the genotypes and different diseases were also analyzed.Although the exact pathogenic mechanism is unclear, one point is very obvious. H.pylori must colonize in the stomach mucus firstly, can then play pathogenic role further. In the gnotobiotic piglet model, the mutant strains of fla gene or aflagellate strains can not colonize in the mucus, so lose pathogenic ability. Studies also show that the strains with stronger motility have stronger pathogenic ability. Now, we have known the flagellar filament contains two main flagellins, the major flagellin, FlaA (53.2kDa) and a minor flagellin, FlaB (53.9kDa).They are coded by flaA gene (1533bp) andflaB gene (1597bp) respectively. The two genes have been cloned and sequenced. Methods1 Isolation and identification of H.pylori: Gastric mucosal biopsy specimens were obtained with routine endoscopy, and daubed on the medium. After incubation at 37 癈 in micro-aerophilic conditions for 5 to 7 days, suspicious colonies were distinguished by typical colonial morphology, straining method, and biochemical reactions. The positive colonies were subcultured and kept at -80C.2 PCR-RFLP of flaA gene: The middle region of flaA gene was amplified by PCR method. PCR products of 970bp were obtained, and the products were digested with restriction endonuclease Hpa II or Hind III. The bands of PCR-RFLP patterns were coded and analyzed by cluster analysis method with the use of SPSS 10.0 software.3 PCR-RFLP offlaB gene: The middle region offlaB gene was amplified by PCR methods. Products of 930bp were obtained. Then PCR products were digested with restriction endonuclease Hpa II or Hindlll. The bands of PCR-RFLP patterns were coded and analyzed by cluster analysis method with the use of SPSS 10.0 software.Results1 PCR-RFLP offlaA gene: There were 4 kinds of restrictionpatterns after PCR products offlaA gene for 46 strains ofH.pylori were digested with Hpall, and 3 kinds of patterns with Hindlll. 46 strains were classified into three genotypes by cluster analysis. There were no relationships between genotypes and different diseases (P=0.294).2 PCR-RFLP offlaB gene: There was only one restriction pattern after PCR products offlaB gene for 46 strains of H.pylori were digested with Hpa II, 2 kinds of patterns with Hindlll. 46 strains were classified into two genotypes by cluster analysis. There were no relationships between genotypes and different diseases (7M).658).3 The comprehensive result of the two genes: If the genotypes of two genes were put togather, 46 clinical strains were classified into three genotypes by cl...
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