Effect of storage and 60Co irradiation on the antiviral activity and subtype pattern of native human interferon-alpha preparations.

The stability of native human leukocyte IFN-alpha was investigated after one year storage at different temperatures, or after sterilization with 60Co-irradiation by determining the total antiviral activity of samples. Inactivation of VSV and Aujeszky virions by 60Co-irradiation was directly related to the radiolysis of samples, indicating the uselessness of this procedure for sterilization of IFN-alpha preparations. The presence and proportion of subtypes in the stored or irradiated preparations (with 50 and 25-70% inactivation, respectively) was analysed by chromatofocusing, comparing their patterns with that of the untreated controls. A logarithmic correlation was found between the pI values and temperature/irradiation sensitivity of subtypes.