Incorporation of immunostimulatory motifs in the transcribed region of a plasmid DNA vaccine enhances Th1 immune responses and therapeutic effect against Mycobacterium tuberculosis in mice

► Hypothesis that mRNA molecules can have potent adjuvant effects in DNA vaccination was tested in vitro and in mice. ► RNA CpG and dsRNA motifs were incorporated into the transcribed region of pVAX1 DNA expressing M. leprae hsp65. ► Inserted immunostimulatory motifs resulted in substantially enhanced Th1 and cellular immune responses in mice. ► Inserted immunostimulatory motifs also enhanced significantly the therapeutic effect of DNA vaccine in mice that had been infected by aerosol with H37Rv.