A recombinant goat pox virus expressing the Brucella OMP25 antigen conferring moderate protection against B. abortus in mice

Brucellosis, a widespread zoonosis that currently lacks safe and efficient vaccines, presenting a serious threat to both public and animal health. Capripoxviruses (CaPV) have emerged as promising vaccine vectors capable of delivering foreign antigens. In this study, we assessed the immunogenicity and protective efficacy of a recombinant goatpox virus (rGTPV) expressing Brucella outer membrane protein 25 (rGTPV-OMP25) in a mouse model. Immunization with rGTPV-OMP25 elicited a robust Brucella-specific IgG response and stimulated a balanced Th1 (IFN-γ, IL-2) and Th2 (IL-4, IL-5) cytokine profile. Following challenge with Brucella abortus S19, vaccinated mice showed a significant reduction in bacterial load in the spleen, indicating partial protection. Although the mouse model (BALB/c) does not fully replicate natural host conditions, it was employed here for preliminary evaluation. Together, these results demonstrate that rGTPV-OMP25 induces both humoral and cellular immune responses and confers measurable protection against B. abortus infection, supporting its potential as a promising vaccine candidate for further development.