In vitro synthesis of poliovirus ribonucleic acid: role of the replicative intermediate.

Poliovirus ribonucleic acid (RNA) polymerase crude extracts could be stored frozen in liquid nitrogen without loss of activity or specificity. The major in vitro product of these extracts was viral single-stranded RNA. However, after short periods of incubation with radioactive nucleoside triphosphates, most of the incorporated label was found in replicative intermediate. When excess unlabeled nucleoside triphosphate was added, the label was displaced from the replicative intermediate and accumulated as viral RNA. It is concluded from this experiment that the replicative intermediate is the precursor to viral RNA. In addition, some of the label was chased into double-stranded RNA. The implications of this finding are discussed.