Brucella Multivalent Antigen-IFN-γ Fusion Protein-Expressing Recombinant Adenoviral Vaccine Induces Th1-Type Immune Responses and Protective Effects Against Brucella Infection in Mice

Brucellosis is a widespread zoonotic disease caused by Brucella species.Infection leads to chronic disease in both humans and animals, complicating pathogen clearance in affected hosts, and it continues to impose a substantial burden on global health and livestock industries.Although several live attenuated vaccines have been widely used in veterinary practice, their efficacy is limited, and they often fail to induce sterilizing immunity.The persistent transmission of brucellosis underscores the need for more effective vaccines to protect susceptible animals and reduce disease incidence.In this study, we first conducted bioinformatics and structural analysis on three candidate Brucella antigens (Cu/Zn-SOD, OMP31, BP26), predicting their stability, hydrophilicity, favorable antigenicity, high solubility, and multiple surface-localized linear B-cell epitopes, which supported their potential as vaccine antigens.We then constructed recombinant adenoviral vaccines expressing Brucella-derived antigens (Cu/Zn-SOD, OMP31, BP26) fused with murine IFN-γ; these vaccines were designated rAd-SG, rAd-OG, rAd-BG, and rAd-Mix (a multivalent combination vaccine).Following evaluation in BALB/c mouse models, we found that these vaccines elicited robust immune responses and conferred significant protection against Brucella melitensis 043 challenge.Collectively, our findings show that the multivalent vaccine (rAd-Mix) induces a Th1-skewed immune response and confers robust protection, representing a promising strategy for developing effective brucellosis vaccines.