A Recombinant Chimera Protein as a Novel Brucella Subunit Vaccine: Protective Efficacy and Induced Immune Response in BALB/c Mice

Background: Brucellosis is one of the main causes of economic loss in domestic animals due to abortions and infertility. Brucella is a facultative intracellular pathogen that survives in other cell types in addition to phagocytes. T cell mediated responses are necessary to eradicate the infection due to Brucella. Objectives: In this study the potential of recombinant protein rTF/Bp26/Omp31 as a novel Brucella subunit vaccine, protective efficacy, and immune response was evaluated in BALB/c mice. Methods: After in silico design of rTF/Bp26/Omp31 structure, the gene was cloned and expressed in Escherichia coli BL21 (DE3). Finally, purified protein by Ni-NTA was used as immunogenic to immunized mice. Results: Mice immunized with rTF/Bp26/Omp31 showed a vigorous humoral and cellular mediated immunity; results were compatible with IgG1 and IgG2a levels as well as high amounts of IFN-gamma, IL-12, IL-4 and IL-10 production in immunized mice, compared with control groups (P < 0.05). Compared to control groups, mice vaccinated with rTF/Bp26/Omp31 showed a significant response and protection against subsequent Brucella infection ( P < 0.05). Conclusions: Statistical analyses indicate similar responses in immunized mice exposed to rTF/Bp26/Omp31, compared with B. abortus RB51 and B. melitensis Rev. 1 vaccines. These results showed the potential of rTF/Bp26/Omp31 as a candidate for the development of a subunit vaccine against brucellosis.