Objective:To investigate the immune efficacy after sequential immunization with Mycobacterium tuberculosis DNA vaccine encoding mature form of Ag85B(pTB30m)and Mycobacterium tuberculosis H37Ra in mice.Methods:Much of highly pure plasmid DNA(pTB30m)extracted by alkaline lysis method was confirmed by restriction endonuclease digestion.Then

its DNA concentration and purity were determined by UV spectrophotometry.At various intervals(4weeks

8weeks)after sequential immunization

ELISA was used to detect the level of the serum antibody against PPD.Also

the spleen lymphocytes of mice were cultured with PPD in vitro.Lymphocyte transformation was detected by MTT assay.Results:Prepared pTB30m was highly pure and came to the needed concentration.Compared with Group Naive control

the specific antibody levels against PPD and the stimulation index(SI)of spleen lymphocytes were all statistically higher in Group DNA-85B/H37Ra(P<0.05)

but the specific antibody levels were not significant different(P>0.05)

as compared with Group DNA-85B/BCG

Group H37Ra and Group BCG

However

compared with Group H37Ra and Group BCG

the SI of mice was significantly larger in Group DNA-85B/H37Ra(P<0.05)

but compared with Group DNA-85B/BCG

it was only statistically higher at 4weeks but not at 8 weeks.Simultaneously

in Group DNA-85B/H37Ra

the SI of the spleen lymphocytes was much higher at 4weeks than that at 8weeks(P<0.05)

but the specific antibody levels were much higer at 8weeks than those at 4weeks(P<0.05).Conclusion:The DNA-85B/H37Ra regimen for tuberculosis prevention in mice stimulate the specific antibody and induce cellular immunity.The immune efficacy of the DNA-85B/H37Ra regimen is slighterly better than that of BCG.