Translation of specific vaccinia virus RNAs purified as RNA-DNA hybrids on potassium iodide gradients.

A procedure has been developed for purifying specific mRNAs by hybridization to fragments of DNA and isolation of the hybrids by potassium iodide equilibrium buoyant density centrifugation. The hybrids obtained are essentially free of unhybridized RNA as well as double-stranded RNA. Moreover, the RNA in the hybrids is undamaged and can be translated in vitro. Application of this procedure to mapping vaccinia virus genes is described. A total of 34 polypeptides have been assigned to three regions of the viral genome.