Diversity of Helicobacter pylori isolates in expression of antigens and induction of antibodies.

AIM: To obtain evidence for selection of antigens used in genetically engineered vaccine against Helicobacter pylori (H pylori).

METHODS

Enzyme linked immunoabsorbent assay (ELISA) was established on the basis of recombinant protein antigens rUreB, rHpaA, rVacA, rCagA1, rNapA, rFlaA and rFlaB of H pylori to detect expression rates of the antigens in bacterial isolates as well as positive rates of the antibodies in sera from H pylori-infected patients. PCR was applied to the detection of carrying rates of the genes encoding antigens in the isolates.

RESULTS

The outputs of rUreB, rHpaA, rVacA, rCagA1, rNapA, rFlaA and rFlaB were approximately 35%, 32%, 15%, 23%, 56%, 25% and 20% of the total bacterial proteins, respectively. One hundred and fifty-one strains of H pylori were isolated from 347 biopsy specimens of chronic gastritis, peptic ulcer or gastric adenocarcinoma, with a positive rate of 43.5%. All of the isolates expressed UreB, HpaA, FlaA and FlaB while 52.3%, 92.1% and 93.4% of the isolates expressed VacA, CagA and NapA, respectively. In the sera of 151 H pylori-infected patients, the positive rates of IgG antibodies against UreB, HpaA, VacA, CagA, NapA, FlaA and FlaB were 100%, 87.4%, 43%, 71.5%, 89.4%, 84.8% and 79.5%, respectively. Furthermore, the expression frequencies of VacA and NapA were found to be relative to the severity of gastric diseases (P=0.016 and P<0.0001, respectively).

CONCLUSION

UreB antigen is the top option of developing genetically engineered vaccine against H pylori followed by NapA or HpaA.