Protective efficacy of an inactivated Brucella abortus vaccine candidate lysed by GI24 against brucellosis in korean black goats

The efficacy of GI24-lysed Brucella abortus cells as a vaccine candidate against brucellosis in goats was evaluated on 2 groups of Korean black goats. Group A goats were immunized subcutaneously (SC) with sterile phosphate-buffered saline, whereas group B goats were immunized SC with approximately 3 × 10 ⁹ lysed B. abortus cells. Subcutaneous immunization with the lysed cells did not cause any negative impact on the overall clinical status, such as behavior and appetite, throughout the study period. The enzyme-linked immunosorbent assay (ELISA) optical densities values for B. abortus lipopolysaccharide in serum were considerably higher in group B than those in group A. Also, the levels of the cytokines interleukin 4 (IL-4), tumor necrosis factor-alpha (TNF-α), and interferon gamma (IFN-γ) were significantly elevated in group B compared with those in group A. Following intraconjunctival challenge with B. abortus strain 544, the severity of brucellosis in terms of infection index and colonization of B. abortus in tissues was significantly lower in group B than in group A. The present study concluded that 3 of 5 goats immunized with GI24-lysed bacteria were completely protected against challenge. Future investigations are required to improve the protective efficacy offered by lysed B. abortus cells for practical applications in small ruminants.