Production and Characterization of Monoclonal Antibodies against Brucella abortus S (99) Surface Antigens

By immunizing mice with killed whole bacterial cells of Brucella abortus S (99), a panel of six hybridomas producing monoclonal antibodies (mAb) specific for the surface antigens of this bacterium were produced. ELISA was used to screen the hybridoma supernatants. Immunoblots of the cell extract indicated that three mAb were specific for S-LPS (Ba-1, Ba-2, Ba-3) and three others were reactive with major outer membrane proteins (OMP) (Ba-4, Ba-5, Ba-6). The OMP recognized by these antibodies were the proteins with molecular masses of 25-27 kDa (Ba-4, Ba-5) and 36-38 kDa (Ba-6). None of the four mAb including Ba-3, Ba-4, Ba-5 and Ba-6 cross reacted with any other bacteria close to Brucella abortus, but Ba-1 and Ba-2 cross reacted with B. melitensis 16M and B. suis. By using cell extract and killed whole cell Ag in ELISA, it was indicated that all mAb except Ba-6 have better reactivity with cell extract Ag, but Ba-6 mAb reacted with killed whole cell Ag better than cell extract Ag.