Induction and measurement of 2',5'-oligoadenylate synthetase in Madin-Darby bovine kidney cells and in cattle.

2',5'-Oligoadenylate [2',5'-oligo(A)] was separated from 14C-labeled nucleosides produced in the 2',5'-oligo(A) synthetase assay by using 100-microliters columns of Dowex 1. No detectable nucleoside remained on the column after elution with 20 column volumes of water, whereas less than 1% of oligonucleotides were eluted from the column. At least 99% of oligonucleotides were eluted from the column with 1 M NaCl, pH 2. The major product had properties consistent with 2',5'-oligo(A). Exposure to alpha-1 bovine interferon (IFN) caused an increase in cellular 2',5'-oligo(A) synthetase activity which was proportional to the concentration of IFN in the medium up to 10(4) U of IFN per ml and then leveled off at about 15 X control activity. Under the assay conditions used, 2',5'-oligo(A) synthetase activity was directly proportional to the amount of cell extract over a 10-fold range. Cattle inoculated with IBR/BVD/PI-3 modified live virus vaccine showed an increase in 2',5'-oligo(A) synthetase activity in peripheral blood mononuclear leukocytes which persisted for at least 3 days postvaccination. Intramuscular injection of cattle with IFN caused a similar increase in 2',5'-oligo(A) synthetase activity. Changes in 2',5'-oligo(A) synthetase activity should be of value in (i) assessing the response of cattle to experimental viral infections or inoculations with viral vaccines or IFN or (ii) indicating a possible viral etiology in disease.