Isolation and study of the properties of an interferon-like inhibitor of viruses from normal human blood serum

A protein with a molecular weight of 17,400 daltons and an isoelectric point at pH 4.9 has been isolated from the blood serum of healthy donors by successive ion-exchange chromatography of QAE-Sephadex A-50, affinity chromatography on DNA-cellulose, and polyacrylamide gel electrophoresis, in the presence of sodium dodecyl sulfate. The protein isolated, like interferon, suppresses the development of the cytopathogenic action of the viruses of vesicular stomatitis and murine ecephalomyocarditis in cultures of human cells of the L-41 and M-19 lines. The amino acid composition of the protein isolated differs from those of various fractions of human interferons.