Bovine leukocyte interferon: characterization and large-scale production.

Natural bovine leukocyte interferon (IFN) was produced in high titer (15,314 U/ml), with Sendai virus as the inducer at 300 hemagglutinating units (HA)/ml and 12 h incubation. Its antiviral activity was completely stable for 30 days at 4 degrees C, -20 degrees C, or -70 degrees C, and 96 h at 37 degrees C, but some activity was lost after 15 min at 56 degrees C. All activity was lost after treatment with trypsin, but pH 2.0 dialysis had no effect. Bovine leukocyte IFN inhibited growth of bovine kidney cells in tissue culture. The system reported could be used to produce bovine leukocyte IFN in quantities sufficient for clinical use in cattle.