Requirement for double-stranded RNA during the in vitro synthesis of RNA by foot-and-mouth disease virus replicase

Thein vitro synthesis of RNA by the RNA-dependent RNA polymerase (replicase) induced by foot-and-mouth disease virus (FMDV) depends upon the conversion of the single-stranded viral RNA into a double-stranded RNA complex. For the first 1.0–1.5 minutes of synthesis, all the RNA formed is double-stranded by virtue of its resistance to pancreatic RNase. Thereafter, the amount of double-stranded RNA remains constant at 21 per cent regardless of the presence or absence of detergents. Equilibrium sedimentation in KI revealed approximately 24 per cent double stranded forms.