The heterologous antiviral efficiency of bacterially produced human interferon (Hu-IFN alpha 2) in the bovine species was studied, using vaccinia infection as experimental model. In a double blind experiment, young calves were intramuscularly injected daily for seven consecutive days with different doses of Hu-IFN alpha 2 or placebo, the treatment starting 24 h before intradermal inoculation of vaccinia virus. A clear protection by interferon was observed in all the IFN treated animals, although individual variations in the sensitivity to IFN were recorded. The efficiency of treatment varied according to the dose of IFN used: With the highest dose (10(6) IU/kg), complete protection could be obtained. The only side-effect observed was hyperthermia. Circulating antiviral activity appeared quite early after each IFN injection, presented a more or less biphasic kinetics, and was completely cleared after 24 h, justifying the daily treatment schedule. The first evidence of an in vivo antiviral effect of human interferon in the bovine species opens broad perspectives for a future use of interferon in veterinary medicine.
Animals Antibodies, Viral