AN ATYPICAL INTERFERON IS INDUCED IN RESP ONSE TO HEAT-SHOCK

Hyperthermia (45-degrees-C) induced the release of heat-shock induced factor(s) (HSIF) in the culture medium of Madin-Darby bovine kidney ce lls (MDBK) during their recovery period at 37-degrees-C. HSIF is capab le of inducing an increase in the 2'5' oligoadenylate synthetase activ ity in fresh MDBK cells without any detectable antiviral activity (Cho usterman et al. J. Biol. Chem. 1987, 262, 4806-4811). We demonstrated here that even though HSIF did not crossreact antigenically with alpha , beta or gamma bovine interferons, it was still also able to induce a n antiviral activity which copurified with its capacity of inducing 2' 5' oligoadenylate synthetase activity. Therefore we concluded that HSI F is an atypical bovine interferon induced in response to heat shock.