Abstract
Viral ribonucleic acid (RNA) from Semliki Forest virus- and Sindbis virus-infected cells was analyzed by electrophoresis on polyacrylamide gels. In contrast to earlier results obtained by sucrose density gradient centrifugation, all of the known viral RNA forms (i.e., the 42S, 26S, replicative form, and replicative intermediate) were very clearly separated. The high resolution of the electrophoretic method permitted the identification of two new single-stranded RNA species. In addition, the replicative form was shown to be heterogeneous and to consist of at least two forms. The results suggested that the replicative forms occur in vivo although in relatively small amounts.