Diagnosis of Helicobacterpyloriinfection and diseases associated with Helicobacter pylori by Helicobacter pylori outer membrane proteins

摘要

sAIM: To examine the serological response of patients with upper gastrointestinal diseases and Helicobocter pylon (Hpy/on)infection to two Hpyloriouter membrane proteins (OMPs) (Mr18 000 and Mr26 000) acquired by gene recombinant technique, and to determine the diagnostic significance of serological tests derived from these OMPs.METHODS: Recombinant vectors encoding the two Hpylori OMPs were used to transform and express in BL21 (DE3) E.coli After purification with NP-NTA agarose resin, colloid gold kits were prepared with purified recombinant proteins to detect H pyloH infection and H pylori-associated diseases by the immunity-marker technology. We selected 150 patients with Hpy/on'infection and digestive symptoms wibhout previous treabnent, including chronic gastritis (n = 60), duodenal ulcer (n = 30), gastric ulcer (n = 30), and gastric cancer (n=30).As controls, 33 Hpylori-negative healthy volunteers were also recruited. Serum samples were collected from all subjects, and the antibodies to specific proteins of Hpylori were tested with the colloid gold test kits. The sensitivity,specificity and accuracy of the colloid gold tests were evaluated, by using the combination of standard diagnostic methods (^13C urea breath test and bacteria culture) and classic enzyme-linked immunosorbent assay (ELISA) as reference.RESULTS: After purification with Ni^2+-NTA agarose resin,the purity of recombinant fusion proteins was about 95%.The recombinant fusion proteins were recognized by the specific monodonal antibodies against bhe two Hpy/oriOMPs,as demonstrated by the ELISA. Of the 150 serum samples from patients infected with Hpy/oH 141 (94.0%) responded positively to the recombinant protein with Mr26 000, while the seropositive rates were 95.0%, 96.7%, 96.7% and 90.0% for patients with H pylori-associated chronic gastritis,duodenal ulcer, gastric ulcer, and gastric cancer respectively.The sensitivity, specificity, and accuracy of the colloid gold kit with Mr26 000 protein were 94.0%, 97.0%, and 94.5%,respe.ctively. Compared with the classic ELISA, bacteria culture and ^13C urea breath test results in detecting Hpyloriinfection, there was no significant difference (P>O.O5). For the colloid gold kit with Mr18 000, the seropositive rates were 52.0%, 40.0%, 40.0%, 53.3% and 86.7%, respectively,in Hpylori-infected palJents, and bhose wibh Hpylori-associated chronic gastritis, duodenal ulcer, gastric ulcer, and gastric cancer. There was a significant difference (P<0.05) in seropositivity between patient with gastric cancer (86.7%) and those with other diseases (43.3%).CONCLUSION: The two colloid gold kits derived from the recombinant OMPs are useful tools either for detecting Hpyloriinfection, or for, predicting Hpylori-associated gastric malignancy.