OBJECTIVE

To determine whether CpG-oligodeoxynucleotide (CpG-ODN) can be an adjuvant for the development of a Helicobacter pylori (H. pylori) vaccine, and explore the role of Th1-type response and gamma-interferon (gamma-IFN) in protection induced by vaccine.

METHODS

Mice were intranasally or orally immunized with H. pylori whole cell sonicate (WCS) and CpG-ODN and challenged with 5 x 10(6) or 5 x 10(8) organisms. The mice were killed 2 and 8 weeks later respectively, the sera, saliva, gastric juice were collected to measure the concentrations of IgG, IgG1, IgG2a and IgA by ELISA, their spleen cells were isolated for analysis of intracellular gamma-IFN and interleukin-4 (IL-4) by flow cytometry.

RESULTS

The prevention rate against H. pylori infection was 70% in mice intranasally immunized with WCS plus CpG-ODN and challenged with 5 x 10(8) CFU H. pylori, and 90% in those challenged with 5 x 10(6) CFU H. pylori. Significantly higher levels of IgG1 and IFN-gamma were found in the mice immunized with WCS/CpG than those in sham-immunized controls (P < 0.05). Spontaneous elimination of H. pylori infection occurred in two of ten sham-immunized mice, whose IgG1 and IFN-gamma levels were higher than those of other sham-immunized ones.

CONCLUSION

CpG-Oligodeoxynucleotide is a potent adjuvant of vaccine against H. pylori, and Th1-type response and gamma-IFN are highly associated with the protective effect.