Abstract
RNA extracted from cells previously stimulated to synthesize the antiviral protein, interferon, causes species-specific interferon synthesis when added to heterospecific cell cultures. Our results confirm the report of De Maeyer-Geugnard, De Maeyer & Montagnier (1972). We have used this observation to obtain a relative quantitative assay for the interferon messenger RNA activity. At appropriate RNA concentrations, the yield of interferon is proportional to the concentration of RNA adsorbed to recipient cell cultures.