Vaccination of goats with a combination Salmonella vector expressing four Brucella antigens (BLS, PrpA, Omp19, and SOD) confers protection against Brucella abortus infection

is an intracellular pathogen with a cellular infection mechanism similar to that of , making it a suitable choice for use in an anti- immune boost system. This study explores the efficacy of a Typhimurium delivery-based combination vaccine for four heterologous antigens ( lumazine synthase, proline racemase subunit A, outer-membrane protein 19, and Cu/Zn superoxide dismutase) targeting brucellosis in goats. We inoculated the attenuated delivery-based vaccine combination subcutaneously at two different inoculation levels; 5 × 10 colony-forming unit (CFU)/mL (Group B) and 5 × 10 CFU/mL (Group C) and challenged the inoculations with virulent at 6 weeks post-immunization. Serum immunoglobulin G titers against individual antigens in immunized goats (Group C) were significantly higher than those of the non-immunized goats (Group A) at 3 and 6 weeks after vaccination. Upon antigenic stimulation, interferon-γ from peripheral blood mononuclear cells was significantly elevated in Groups B and C compared to that in Group A. The immunized goats had a significantly higher level of protection as demonstrated by the low bacterial loads in most tissues from the goats challenged with . Relative real-time polymerase chain reaction results revealed that the expression of antigens was lower in spleen, kidney, and lung of immunized goats than of non-immunized animals. Also, treatment with our combination vaccine ameliorated histopathological lesions induced by the infection. Overall, the Typhimurium delivery-based combination vaccine was effective in delivering immunogenic proteins, making it potentially useful in protecting livestock from brucellosis.