The long-term stability of recombinant (serine-17) human interferon-beta

Escherichia coli-derived (Serine 17) human interferon-beta (HuIFN-beta SER) was formulated with SDS and placed at multiple isothermal temperatures (-70 degrees C to 37 degrees C). Three stability-indicating test methods (bioassay, SDS-PAGE, RP-HPLC) were used to evaluate the long-term stability of this preparation. No change was observed when stored for nearly a year at either -70 degrees C or 4 degrees C. At the elevated temperatures, proteolytic cleavage, noncovalent oligomer formation, and loss of antiviral activity were observed. The absence of a carrier protein makes this stable IFN-beta frozen reference preparation useful as a standard in both biological assays and protein chemical methods of analysis.