Brucellosis is one of the major zoonotic infections worldwide, continues to be a public health
problem resulting in significant morbidity and economic losses. Accurate diagnosis must include
laboratory tests that allow the direct Brucella isolation or indirect detection of antibodies. Practical
serological tests are routinely used for the diagnosis of brucellosis by using specific antigens. In
the present work, the used buffered acidified plate antigen (BAPA) was prepared from B. abortus
biovar 1 strain S1119-3 according to the USDA SOPs. For this purpose, a total of 4100 bovine sera
from five farms located in different governorates were screened for brucellosis. The effectiveness
of prepared BAPA from strain 19 was compared with the standard BAPA and BCT antigens
prepared from B. abortus strain 99. Evaluation was done by using a panel of known dilutions of
the OIEISS (Office International des Epizootie International Standard Serum) as the international
reference standard serum. There were no significant differences in results of the BAPA antigen
prepared from strain 19 and the conventional antigen prepared from strain 99. The results
concluded that, the vaccinal strain 19 can be used instead of strain 99 to prepare the BAPA antigen.