Abstract

Tuberculosis remains a major infectious disease worldwide. There are no effective vaccines developed for the disease so far and the efficacy of the only available vaccine, Mycobacterium bovis Bacillus Calmette–Guérin (BCG) is generally low against Mycobacterium tuberculois(MTb). DNA vaccine is especially becoming promising and novel vaccine approach. In this study, a plasmid DNA vaccine, pVAX1-MPB64-Ag85B (pMB), was constructed and designed to express a fusion protein MPB64, Ag85B of MTb. Its immunogenicity and protective efficacy were assessed in a mouse model of tuberculosis. Vaccination with the pMB significantly increased the frequency of peripheral blood CD4⁺ and CD8⁺ T cells, and induced significantly higher levels of cell-mediated immune responses, as compared with vaccination with PBS or the pVAX1 empty vector. High levels of antibodies observed in the sera of immunized mice depicted strong humoral responses generated by DNA vaccine constructs. All the experimental vaccines imparted significant protection against challenge with M. tuberculosis H37Rv as compared to vector controls. These results show that the newly developed pMB vaccine may be used for the prevention and therapeutic intervention of MTb infection.

Key words: Mycobacterium tuberculosis, Ag85B , MPB64, DNA vaccine.