SEROLOGICAL RESPONSE OF CATTLE TO BRUCELLA ALLERGEN AFTER REPEATED INTRADERMAL APPLICATIONS OF THIS ALLERGEN

A study was conducted to determine whether an allergen that has been p repared from a mucoid strain of Brucella abortus triggers a serum anti body response that interferes with the interpretation of serologic tes ts results. Fifteen cattle seronegative for Brucella antigen were test ed with the SDTH test several times, Blood samples were collected week ly and tested with the serum agglutination test and complement fixatio n test. Results show that some cattle tested seronegative after each o f the SDTH tests while other cattle tested weakly positive with the se rum agglutination test or the complement fixation test. All seropositi ve cattle tested seronegative 4-7 weeks after the last SDTH test indic ating an antibody response of a transient nature. We conclude that ser ologic tests results indicating infection are reliable when recorded f our weeks after a single SDTH test. If cattle are tested with the SDTH test several times an interval of seven weeks should be observed afte r the last test to ensure a reliable interpretation of the serologic t ests results.