Actinomycin-resistant antiviral activity associated with preparations containing chicken interferon. 
Crude and purified preparations containing chicken interferon show a 2fold antiviral activity.  One is inhibited by actinomycin and leads to total inhibition if interferon is added to cells before actinomycin, the other is insensitive to actinomycin and leads to partial inhibition if interferon is added simultaneously with or after actinomycin.