[Effect of the immune strategy based on BCG priming and Ag85A/GM-CSF DNA vaccine boosting in mice]

To investigate immune effect in mice on the basis of BCG priming and DNA vaccine boosting, and to provide a new strategy for development of new type of anti-tuberculosis DNA vaccine further.

After mice were inoculated with BCG of 1x10(6) clone formation unit each three weeks, 100 microg of DNA vaccine was injected intramuscularly in mice two times at 3 week intervals. The proliferative responses of murine cytotoxic T lymphocytes (CTL), natural killer (NK) and spleen cell to antigen 85A(Ag85A) were measured by MTT method respectively. The antibody titers and IFN-gamma level from the immunized mice were detected by ELISA.

The proliferative responses of CTL and spleen cell to Ag85A, as well as IFN-gamma level in mice immunized with prime-boost strategy were significantly increased respectively compared with the control mice immunized with blank plasmid or BCG only. Although NK activity was a little higher in mice immunized with prime-boost strategy than that of immunized with blank plasmid mice, it was still lower than that of mice immunized with BCG alone. The titer of the specific antibody against Ag85A in mice immunized with prime-boost strategy was also higher than that of mice immunized with DNA vaccine alone.

The immune strategy of BCG-prime and Ag85A/GM-CSF DNA vaccine boost improve immune effect, especially the Th1 cellular immune response increase obviously. This study provides the possibility of further research for investigating protective function in immunized mice challenged by Mycobacterium tuberculosis.