IMMUNE-RESPONSE OF CALVES EXPERIMENTALLY INFECTED WITH NON-CELL-CULTURE-PASSAGED BOVINE RESPIRATORY SYNCYTIAL VIRUS

The immune response of calves was studied following infection with non -cell-passaged Bovine respiratory syncytial virus (BRSV). Two groups o f 6 specific pathogen free (SPF) calves were housed in separate isolat ion rooms. One group was inoculated intranasally with a non-cell-passa ged BRSV strain and the control group was mock-infected. A BRSV specif ic antibody response was observed for all the BRSV infected calves. Th ese antibodies were shown to have neutralizing activity. No lymphocyte proliferation response was detected in the mock-infected group wherea s three animals in the infected group were positive three weeks after the infection. All BRSV-infected calves, except one, produced interfer on-gamma (IFN-gamma) one week post-infection and IFN-gamma was observe d in all six infected calves after three weeks. The control group show ed no IFN-gamma synthesis. In spite of the limits of the BRSV infectio n model, humoral and cellular immune responses were actively developed by all the calves against this pathogen.