• rBP26 combined with CpG adjuvant induces M1 macrophage polarization and Th1-mediated cellular immune responses.
• The vaccine generates high levels of rBP26-specific antibodies and activates CD8+ T cells.
• Immunization with rBP26 promotes T lymphocyte proliferation, cytokine production, and long-term immune memory.
• rBP26 is a promising subunit vaccine candidate for brucellosis, especially in endemic regions.