Production and evaluation of anti-BP26 monoclonal antibodies for the serological detection of animal brucellosis

Abstract

Brucella BP26 proves to be a highly immunogenic antigen with excellent specificity in brucellosis detection. In China, the authorized use of the Bp26-deleted vaccine M5ΔBP26 for preventing small ruminant brucellosis highlights the importance of developing accurate detection methods targeting BP26, particularly for the diagnosis of differentiation between infected and vaccinated animals (DIVA). Using the traditional mouse hybridoma technique, we successfully obtained 12 monoclonal antibodies (mAbs) targeting BP26. The efficacy of these mAbs in detecting various animal brucellosis cases using the competitive ELISA method was evaluated. Among them, only the E10 mAb exhibited significant efficiency, being inhibited by 100, 97.62, and 100% of brucellosis-positive sera from cattle, small ruminants, and canines, respectively. The E10-based competitive enzyme-linked immunosorbent assay (cELISA) outperformed the BP26-based indirect enzyme-linked immunosorbent assay (iELISA) in accuracy, particularly for cattle and small ruminant brucellosis, with cELISA sensitivity reaching 97.62% compared to 64.29% for iELISA for small ruminants. Although cELISA showed slightly lower specificity than iELISA, it still maintained high accuracy in canine brucellosis detection. The epitope of mAb E10 was identified in the amino acid sequence QPIYVYPDDKNNLKEPTITGY, suggesting its potential as a diagnostic antigen for brucellosis. In conclusion, the E10-based cELISA presents an effective means of detecting animal brucellosis, particularly significant for DIVA diagnosis in China, where the BP26-mutant vaccine is widely used.