Use of recombinant bovine alpha 1 interferon in reducing respiratory disease induced by bovine herpesvirus type 1.

Intranasal or intramuscular treatment of calves with recombinant bovine alpha 1 interferon before challenge with bovine herpesvirus type 1 and Pasteurella haemolytica reduced clinical signs, number of sick days, lung lesions, and weight loss. The effective dose was determined to be relatively broad within the range of 1 to 50 mg per animal. No adverse effects were observed even at high doses of interferon (50 mg per animal). Administration before virus infection was more effective than administration at the same time as virus infection. Although interferon administration had dramatic effects on the survival of animals, it did not have much effect on virus secretion in the upper respiratory tract. Therefore, the mechanism by which interferon reduces the susceptibility of animals to viral-bacterial synergy was postulated to be via its immunomodulatory effects.