Synthesis of all the gene products of the reovirus genome in vivo and in vitro

Abstract

Sixteen virus-specific polypeptides have been resolved in reovirus-infected mouse L cells by using SDS-polyacrylamide slab gel electrophoresis and autoradiography. Of these, ten have been designated as primary products of the genome by the following criteria: • — they are present in lysates of infected cells labeled for a short time; • — they co-migrate on SDS-polyacrylamide slab gels with polypeptides synthesized in cell-free extracts of wheat germ in response to purified viral mRNA; • — and their molecular weights correspond to the values expected if all ten reovirus mRNA species are monocistronic. Reovirus mRNA species lack 3′ poly(A) but are translated into proteins of the expected size. The pattern of synthesis of the primary gene products observed in vitro mimicks that observed in reovirus-infected cells suggesting that the structure of the mRNA may profoundly influence its translation. The results further indicate that there is little, if any, exclusively regulatory information in the reovirus genome since both in vivo and in vitro, transcripts of the ten genome segments direct the synthesis of ten polypeptides that presumably correspond to the primary gene products. The expression of the reovirus genome thus appears to be complete.