Immunohistochemical detection of Brucella abortus antigens in tissues from aborted bovine fetuses using a commercially available polyclonal antibody.

A commercially available polyclonal antibody and an avidin-biotin-peroxidase immunohistochemical technique were used to detect Brucella abortus antigens in formalin-fixed, paraffin-embedded tissues of lung and liver from 20 aborted bovine fetuses. Thirteen fetuses were obtained from farms with a previous history of brucellosis, and 7 were collected from farms without a history of brucellosis. Among the 13 aborted bovine fetuses obtained from farms with a history of brucellosis, immunoreactivity to B. abortus was detected in lung (9 fetuses) and in liver (1 fetus), whereas Brucella was cultured from abomasal contents in 9 fetuses (8 were immunohistochemically positive). In addition, 11 dams of these 13 aborted bovine fetuses had antibodies to Brucella. Brucella abortus was not detected by immunohistochemistry in the 7 aborted bovine fetuses collected from farms without a history of brucellosis. Bacteriologic culture and serologic tests were also negative for Brucella. The results of this study revealed that the immunohistochemical technique was sufficiently sensitive for detecting B. abortus antigens in formalin-fixed lung tissues from naturally aborted bovine fetuses. Although additional studies are necessary to rule out cross-reaction of the polyclonal antibody with other microorganisms that cause bovine abortion, this immunohistochemical technique could be a complementary tool to serology and bacteriology for the diagnosis of brucellosis.