Abstract Background and Objective: One of the proteins shared in all strains of Brucella is 31 kDa surface protein (BCPS31) that could be an appropriate target for immunization and serological diagnosis. Material and Methods: In the present study, BCSP31 produced as a recombinant protein in pET28a (+) expression system was utilized, using ELISA, to detect trace specific antibody (IgG) in brucel...