On the Biosynthesis and Structure of Double-Stranded RNA in Vaccinia Virus-Infected Cells

The virus-specific, RNase-resistant RNA appearing in vaccinia virus-infected cells was directly shown to be an RNA duplex. After its melting and subsequent banding on Cs₂SO₄ or incubation with DNase, the RNA could be reannealed and then hybridized with vaccinia virus DNA. The double-stranded virus-specific RNA appears to exist in the cell in the form of heterogeneous partially double-stranded RNA's sedimenting between 9 and 22S. The kinetics of the appearance of the double-stranded RNA in the cell show a dependence on the multiplicity of infection and suggest that the double-stranded RNA is a "late" product of viral intracellular biosynthesis. The synthesis of the double-stranded RNA is inhibited by actinomycin D.