Protective efficacy of a brucella vaccine using a salmonella-based delivery system expressing brucella omp3b, bcsp31, and sod proteins against brucellosis in Korean black goats

This study aimed to assess the protective efficacy of a novel Brucella vaccine formulation in goats. Twenty black goats were separated into 2 groups. Group A was injected with 3.0 3 10⁹ CFU (colony-forming units)/mL of a Salmonella-based delivery system harboring only vector (pMMP65). Group B was immunized with 3.0 3 10⁹ CFU/mL of the vaccine, a mixture of 3 Brucella vaccine strains (using a Salmonella-based delivery system) expressing each recombinant B. abortus Omp3b, BCSP31, and SOD protein. No Salmonella delivery strain was isolated from all tested lymph nodes and parenchymal organs. Serum immunoglobulin (Ig) G titers and interferon gamma concentrations were significantly higher in group B than those in group A. After intraconjunctival challenge with virulent B. abortus strain 544, 40% of the vaccinated animals in group B were protected against B. abortus infection. The infection index and colonization of B. abortus in tested tissues was significantly lower in group B than group A. We conclude that this Brucella vaccine induces significant antigen-specific immune responses and provides effective protection against B. abortus infection in goats. Further studies are needed to enhance the protection rate of this Brucella vaccine and to discover its practical application in small ruminants.