In vivo electroporation of a codon-optimized BERopt DNA vaccine protects mice from pathogenic Mycobacterium tuberculosis aerosol challenge

Abstract DNA vaccines have been extensively studied as preventative and therapeutic interventions for various infectious diseases such as tuberculosis, HIV/AIDS and influenza. Despite promising progresses made, improving the immunogenicity of DNA vaccine remains a technical challenge for clinical development. In this study, we investigated a tuberculosis DNA vaccine BER opt , which contained a codon-optimized fusion immunogen Ag85B-ESAT-6-Rv2660c for enhanced mammalian cell expression and immunogenicity. BER opt immunization through in vivo electroporation in BALB/c mice induced surprisingly high frequencies of Ag85B tetramer + CD8 + T cells in peripheral blood and IFN-γ-secreting CD8 + T cells in splenocytes. Meanwhile, the BER opt vaccine-induced long-lasting T cell immunity protected BALB/c mice from high dose viral challenge using a modified vaccinia virus Tiantan strain expressing mature Ag85B protein (MVTT-m85B) and the virulent M. tb H37Rv aerosol challenge. Since the BER opt DNA vaccine does not induce anti-vector immunity, the strong immunogenicity and protective efficacy of this novel DNA vaccine warrant its future development for M. tb prevention and immunotherapy to alleviate the global TB burden.