Interleukin 12 Improve The Efficacy Of DNA Vaccines Against Mycobacterium Tuberculosis

To study the efficacy of interleukin 12 enhancing immune response and protective potential of DNA vaccine against Mycobacterium tuberculosis . Plasmid expressing Murine IL-12 was combined with DNA vaccines encoding Mycobacterium tuberculosis secretive protein Ag85B, MPT64 and fusion protein Ag85B-MPT64 respectively, or mixed with Ag85B and MPT64 DNA together. Mice C57BL/J6 were immunized with these combination DNA and challenged via vein injection with Mycobacterium tuberculosis H37Rv 4 weeks after the last immunization. The serum anti-PPD antibody, IL-12 and antigen-specific production IFN-γwere detected by ELISA. Bacteria load and weight index(WI) in lung and spleen were counted. Lung tissue were stained with HE and anti-fast stain for pathologic analysis. The results showed that co-delivery pIL-12 with DNAvaccines increased the protective cellular immune response and decreased the bacteria load in lung significantly compared with groups without pIL-12. And remarkable protective efficacy against Mycobacterium tuberculosis was observed in mice co-immunized with multi-DNA combination or with DNA encoding fusion protein and comparable to BCG. Therefore, co-delivery of IL-12 plamid with multi-DNA vaccines may be a potent strategy for enhancing the protective efficacy against M.tuberculosis.