IBT/020 Dynamics of antibody response in buffalo calves vaccinated with Brucella abortus S 19 using various serological assays

Brucellosis caused by B. abortus is a serious problem in buffaloes in India. Abortion is the main outcome of brucellosis in pregnant animals with further complication of retention of placenta, reduced milk yield, metritis, temporary or permanent infertility, cost of veterinary services, increased inter-calving period and maintenance of unproductive animal. One organized government buffalo farm located at Hisar in the state of Haryana, suffered severe outbreak of abortions due to brucellosis which was established on the basis of isolation of brucellae and serological evidence. For controlling the disease testing, segregation and vaccination with B. abortus S19 vaccine was adopted despite vaccination of buffaloes is not normally practiced in India. Whole herd was vaccinated and dynamics of antibody response in 25 serologically negative Murrah buffalo female calves, aged between 4 and 8 month, was studied using five serological assays viz. Rose Bengal test (RBT), serum agglutination test (SAT), dithiothreitol test (DTT), ELISA and fluorescence polarization assay (FPA). Each calf was inoculated subcutaneously with standard dose of vaccine containing 40×10⁹ organisms (Indian Immunologicals Ltd., India) and dynamics of antibody was observed on day 15, 30 and 90. On day 15 antibody was detected in all calves by RBT, SAT, DTT and ELISA, however, all the calves were negative in FPA. The similar status of antibody response maintained till day 30. On day 90 antibody status remained the same in RBT, SAT and ELISA, declined in DTT (75%) and none of the calves gave positive FPA reaction. These preliminary data indicated that B. abortus S19 vaccine provoked antibody response in buffalo calves and dynamics of antibody could be assessed by assays used. However, FPA did not detect the antibody response in vaccinated buffalo calves.