Virus Protein Synthesis in Animal Cell-Free Systems: Nature of the Products Synthesized in Response to Ribonucleic Acid of Encephalomyocarditis Virus

Abstract

Ribonucleic acid (RNA) from encephalomyocarditis (EMC) virus stimulates the incorporation of amino acids into protein in cell-free protein-synthetic systems derived from Krebs mouse ascites tumor cells and chick embryo fibroblasts; the mouse system is the more responsive to the viral RNA. The greater part of this difference in activity can be ascribed to the cell sap, but the origin of the ribosomes also has a marked effect. The nature of the polypeptides formed in these cell-free systems was investigated by electrophoresis on polyacrylamide gels and by fingerprint analysis of tryptic digests. The same product in part appears to be synthesized in response to the EMC RNA in both systems. It was not detected if the EMC RNA was partly degraded (≤4 S ) or replaced by other species of RNA, including that from influenza virus. The results suggest that EMC RNA is partially translated in these systems to yield virus-specific polypeptides.