DDA is More Efficacious Than MPL as Adjuvants That Enhanced Immunogenicity and Protection of Combined DNA Vaccine Against Mycobacterium tuberculosisa

Combined DNA vaccine encoding Ag85B, MPT64 and MPT83 of Mycobacterium tuberculosis were formulated into DDA and MPL to immunize mice and then the immunogenicity and protective efficacy of each group were evaluated. The DDA and MPL groups induced a much more enhanced Th1-type cellular response indicated by the higher levels of IFN-γ compared with that without any adjuvant. In DDA group, antigens specific IFN-γ for Ag85B, MPT64, MPT83 are (265.37±79.2) U/ml,(185.31±58.3) U/ml,(108.13±54.4) U/ml respectively which are 16 U/ml,45 U/ml,2 U/ml higher than that of the non-adjuvant group. The bacterial CFU in lungs and spleens of the DDA group was reduced 1/5 and 1/4 respectively relative to the same combined vaccine with MPL and without adjubvants. The pathological lungs slices of adjuvant groups gave consistent result that showed less damage than non-adjuvant group due to influx of epithelioid macrophages and less neutrophils. In conclusion, DDA is more efficacious than MPL as adjuvants to enhance immune efficacy of combined DNA vaccine in mice.