Purification and characterization of chick interferon induced by viruses

Chick interferon (IFN), produced in primary chick embryo (CE) cells stimulated by u.v.-irradiated Newcastle disease virus, was partially purified by two-step chromatography using both controlled pore glass and Blue Sepharose. The specific activity of the IFN increased about 500-fold by this method and the final recovery from starting material was more than 95%. The partially purified IFN was analysed by SDS-PAGE, and two peaks of IFN activity were observed. The molecular weight represented by the sharp peak was estimated to be 18 000 (18K) and a broad peak was found at 20K to 30K. Glycosidase treatment before SDS-PAGE resulted in disappearance of the broad peak and increased the activity of the 18K peak. Anti-CE IFN rabbit serum and a monoclonal antibody against the CE IFN neutralized the antiviral activity of all IFN samples prepared under various conditions.