Immunization of BALB/c mice against virulent Brucella abortus and Brucella melitensis by vaccination with recombinant OrF

Brucellosis is a zoonotic disease that remains challenging despite the development of numerous vaccines. Several problems with existing live attenuated vaccines have led researchers to develop new vaccines. To determine if inducing immune responses against virB12 proteins can offer protection against brucellosis, this study evaluated the production of immune responses against virB12 proteins. The purification of orf gene was accomplished using cloning, expression, and western blot evaluation. Six-week-old female BALB/C mice were subcutaneously injected with 16 g of roprf three times at intervals of 10 days. Blood samples were examined for specific total serum immunoglobulin (IgG)1, IgG, and IgG2a levels via indirect ELISA. Cell-free culture media were assayed by specific ELISAs to assess interleukin (IL)-10, IL-4, IL-12, and interferon gamma (IFN-gamma) levels. This method resulted in significantly higher yields of recombinant Orfs (rOrfs), measured at 3.4 mg from 1 l of induced culture. Mice immunized with rOprF produced significantly higher levels of IL-12, IL-4, and IFN-gamma, but no significant differences in IL-10 production compared to other groups of mice. On the other hand, mice immunized with rOrfs developed significantly higher levels of IgG1, IgG, and IgG2a compared to other groups. Overall, the findings imply that rOrfs stimulates defense against Brucella melitensis and Brucella abortus and may be a candidate for subunit brucellosis vaccine development.