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AIM To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic.METHODS Three strains of H. pylori, isolated from gastric biopsy specimens of confirmedpeptic ulcer, were converted from spiral into coccoid from by exposure to metronidazole. Both spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the proteinwere analysed by SDS-PAGE and Western blot.The mutation of the genes including ureA, ureB, hpaA, vacA and cagA, related with virulence,was detected by means of PCR and PCR-SSCP.RESULTS In the coccoid H. pylori, the urease activity, the adherence to Hep-2 cells and thevacuolating cytotoxicity to Hela cells alldecreased. In strain F_(44), the rate and index ofadherence reduced from 70.0%?5.3% to 33% ?5.1% and from 2.6?.4 to 0.96?.3 (P<0.01),respectively. The invasion of coccoid H. pylori into Hep-2 cell could be seen underelectronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over M_r 74 000 decreased, and the hybriditional signal in band M_r 125 000 weakened, while the band M_r 110 000 and M_r 63 000 strengthened in coccoid H. pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA.CONCLUSION The virulence and the proteins with molecular weight over M_r 74 000 in coccoid H. pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA,vacA and cagA genes, suggesting that coccoid H. pylori may have potential pathogenicity.
AIM To explore the virulence and the potential pathogenicity of coccoid Helicobacter pylori (H. pylori) transformed from spiral form by exposure to antibiotic. METHODS Three strains of H. pylori, isolated from gastric biopsy specimens of confirmedpeptic ulcer, were converted from spiral into coccoid both by spiral and coccoid form of H. pylori were tested for the urease activity, the adherence to Hep-2 cells and the vacuolating cytotoxicity to Hela cells, and the differences of the protein web analyzed by SDS-PAGE and Western blot. The mutation of the genes including ureA, ureB, hpaA, vacA and cagA, related with virulence, was detected by means of PCR and PCR-SSCP. RESULTS In the coccoid H. pylori, the urease activity, the adherence to Hep- 2 cells and the vacuolar cytotoxicity to Hela cells all established. In strain F_ (44), the rate and index of atherence reduced from 70.0% ~ 5.3% to 33% ~ 5.1% and from 2.6 ~ .4 to 0.96 ~ .3 (P <0.01 ), respectively. The invasion of co ccoid H. pylori into Hep-2 cell could be seen underelectronmicroscope. SDS-PAGE showed that the content of the protein with the molecular weight over M_r 74 000 decreased, and the hybriditional signal in band M_r 125 000 weakened, while the band M_r 110 000 and M_r 63 000 strong in coccoid H. pylori as shown in Western blot. The results of PCR were all positive, and PCR-SSCP indicated that there may exist the point mutation in gene hpaA or vacA.CONCLUSION The virulence and the proteins with molecular weight over M_r 74 000 in coccoid H. pylori decrease, but no deletion exists in amplification fragments from ureA, ureB, hpaA, vacA and cagA genes, suggesting that coccoid H. pylori may have potential pathogenicity.