Evaluation of Triple Fragment Vaccine HSPX (Rv2031c) + PPE44 (Rv2770c) + Mouse IgG(1 )(Fcγ2a) with Auxiliary Adjuncts IL-22 in Comparison with BCG Vaccine

BACKGROUND & OBJECTIVE: Despite the vaccination with the BCG vaccine, tuberculosis (TB) remains one of the major health problems in the world. The aim of this study was to evaluate our newly designed vaccine using IL-22 as an adjuvant in comparison with the common BCG vaccine. METHODS: The gene constructs were cloned into the expression vector of pET28a and then into the recombinant vector of PET28a – HSPX, and PPE44 was transformed into Escherichia coli BL21 (DE3). Finally, the immunogenicity of recombinant proteins with and without BCG and IL-22 in BALB/c mice was investigated. RESULTS: The key cytokines INF-γ and TNF-α were elevated more greatly in BCG immunized group than in PHF immunized group. Immunization with PHF showed a significant increase in IL-4 levels versus the BCG group. Adding IL-22 to the vaccine formulations indicated a tiny increase in IL-4 levels compared to their related vaccine groups. Specific total IgG1 in the experimental groups showed an increase in comparison with control groups, but in the vaccinated groups, no significant differences were observed, and the presence of IL-22 in the vaccine formulations indicated a slight decrease compared with the related mere vaccine groups. Results of specific total IgG2a in the experimental groups revealed that only in the PHF group formulated with IL-22 a significant increase occurs compared with all other experimental groups. CONCLUSION: It seems that BCG, as the only licensed vaccine for TB infection, could be more potent than a recombinant vaccine in the induction of cellular and humoral immune responses.