Characterization of Chick Embryo Interferon Induced by a DNA Virus

Biochemical, biophysical and biological characterization was carried out previously for highly purified chick embryo interferon induced by an RNA virus, influenza A (RNA-interferon). The present report summarizes the findings in studies to characterize partially purified chick embryo interferon induced by a DNA virus, herpes simplex (DNA-interferon). DNA-interferon was shown to be a protein of low molecular weight (about 36,000) which is trypsin sensitive, relatively heat stable (70°C) and is stable over a wide range of pH (pH 1 to 11). The findings by others are reviewed and analyzed. Development of a new method for measuring isoelectric point based on pH elution profile from CM-sephadex established the isoelectric point for DNA- and RNA-in-terferon at pH near neutral. Both DNA-and RNA-interferon were active against vesicular stomatitis virus in the homologous chick cell culture system but showed no activity against this virus in mouse embryo, grivet kidney, bovine kidney or rabbit kidney cell cultures. The remarkable similarity of chick DNA-interferon to RNA-interferon, even though induced by basically different agents, is consistent with the concept that interferon is synthesized by resident host mechanisms rather than under the viral genetic code.