Mycobacterium bovis BCG expressing the proteins CP40 or CP09720 of Corynebacterium pseudotuberculosis promotes protection in mice after challenge.

• The rBCG expressing rCP40 and rCP09720 proteins protect against C. pseudotuberculosis. • Mycobacterium bovis BCG/cp40 boosted with rCP40 (G5) showed 90% protection after challenge. • Besides eliciting an expected cross-immune response, rBCG induced specific humoral and cellular responses. In this study, we assessed the survival and immune response of mice vaccinated with recombinant Mycobacterium bovis BCG Pasteur that expressed the CP40 or CP09720 proteins after the mice were challenged with a C. pseudotuberculosis MIC-6 virulent strain. Six groups of mice (n = 10 mice per group) were immunised with a sterile 0.9% saline solution (G1), 106 CFU of M. bovis BCG Pasteur (G2), 106 CFU of M. bovis BCG/ cp40 (G3), 106 CFU of M. bovis BCG/ cp09720 (G4), M. bovis BCG/ cp40 boosted with rCP40 (G5), and M. bovis BCG/ cp09720 boosted with rCP09720 (G6). The highest survival rate of 90% was observed in the G5 group, followed by 80% in the G6 group and 70% in the G3 and G4 groups. Moreover, a significantly greater induction of IFN-γ and IL-10 was found in the G3 group and higher IL-17 levels were recorded in the G5 group compared to their levels in the control group (G1) (p < 0.05). A specific humoral immune response (total IgG) was found in the G5 and G6 groups on day 42 compared to the level of response in the G1 group. These results indicated that the vector vaccine elicited significantly greater survival of mice in all experimental groups after a strong virulent challenge and induced a strong immune response. [ABSTRACT FROM AUTHOR]