Induction of circulating interferon in calves with three different types of double stranded ribonucleic acid.

Three double-stranded ribonucleic acids (dsRNA), given intravenously, were evaluated for interferon induction in calves. Groups of four calves were given an initial injection then, 24 h later, a second injection of each dsRNA material. The synthetic dsRNA, poly I.poly C, at 0.5 mg/kg stimulated serum interferon in two calves after an initial injection and in three calves after a second dose, whereas a natural dsRNA (BRL 5907) at 0.5 mg/kg induced interferon in only one calf after both injections. A polyquaternary ammonium complex (BRL 10739) of natural dsRNA, at 0.1 mg/kg, induced interferon in all four calves after a single injection and circulating interferon persisted longer than with the other two dsRNA materials.