Protection Provided by an Encapsulated Live Attenuated ΔabcBA Strain of Brucella ovis against Experimental Challenge in a Murine Model

This study aimed to evaluate the B. ovis Δ abcBA strain as a vaccine candidate in the murine model. BALB/c mice were subcutaneously or intraperitoneally immunized with single dose or three doses of B. ovis Δ abcBA strain, and then challenged with wild type B. ovis . Single or multiple immunizations provided only mild protection, with significantly lower numbers of wild type B. ovis colony forming units (CFU) in the liver of immunized mice, but not in the spleen. Encapsulation of B. ovis Δ abcBA significantly improved protection against experimental challenge in both BALB/c and C57BL/6 mice. Furthermore, immunization with encapsulated B. ovis Δ abcBA markedly prevented lesions in the spleen and liver of experimentally challenged mice. These results demonstrated that encapsulated B. ovis Δ abcBA strain confers protection to mice and, therefore, this strain has potential as a vaccine candidate for rams.