| Summary: | 碩士 === 國立陽明大學 === 醫學生物技術研究所 === 93 === Helicobacter pylori is a gram-negative microaerophilic bacillus colonizing the human stomach and more than 50 % of the world,s population is infected .Infection with H.pylori has been associated with chronic gastritis、peptic ulcers and gastric adenocarcinoma.H.pylori possesses several virulence factors,such as urease,Flagella,Neutrophil activation protein(NAP),BabA,SabA,vacuolating cytotoxinA(VacA) and cytotoxin- associated gene A(cagA).In this study,we analyzed the genotype of 594 H.pylori strains isolated from 99 patients (20 from Gastric cancer,32 from Gastric ulcer,31 from Duodenal ulcer,16 from Chronic gastritis)The analyzed genes include vacA,cagA,cagE,cagT and cagM .
In vacA signal region: 591(99.5%) of 594 strains had s1a type (three strains can´t be detected).No strain with s1b or s2 was found.In vacA middle region:97 strains (16.3%) were classified as m1t type .352 strains (59.3%) were classified as m2 type .145 strains (22.4%) were classified as Non m1-m2 type .VacA m1t type was found more frequently in gastric cancer than gastric ulcer or duodenal ulcer(35.8% vs 9.4%、9.7%,P<0.0001).To combine signal and middle region,the percentage of s1a-m1t,s1a-m2 and s1a-Non m1 m2 genotype were 16.3% ,58.8% and 24.4% , respectively .
The cagA gene was detectable in 99.3%(590/594) of samples ,cagE gene was 96.1% (571/594),cagT gene was 99.0%(588/594), cagM gene was 98.5% (585/594).We use PCR reaction for typing of CagA C-terminal EPIYA motif .Several types of PCR products were found ,including 350bp (1.0%),400bp (95.5%),450bp (2.9%) and 550bp(0.7%).After nucleotide sequencing ,two EPIYA motif were found in the 350bp product and the sequence alignment suggested it to be a B-D type,three EPIYA motif (A-B-D type),four EPIYA motif (A-A-B-D type),and another four EPIYA motif (A-A-X-D type) were found in the 400bp,450bp,and 550bp PCR product, respectively .
There are some patients with more than one genotype of H.pylori,named mix infection.The mix infection rate of our study was 18.2%.
In conclusion,almost all the isolates were cagA,cagE,cagT and cagM positive.s1a-m2 was the major vacA genotype of the whole isolates . However ,s1a-m1t genotype was the major vacA genotype among gastric cancer populations than peptic ulcer populations .
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