Intracellular forms of Adenovirus DNA. II. Isolation in dye-buoyant density gradients of a DNA-RNA complex from KB cells infected with Adenovirus type 2.

DNA-RNA complexes with different DNA/RNA ratios have been isolated from KB cells productively infected with human adenovirus type 2 by the dye-buoyant density procedure by using propidium iodide. Both the DNA and RNA components of these complexes are virus specific, and parental as well as newly synthesized viral DNA can be recovered from these complexes. The RNA component is susceptible to digestion with pancreatic ribonuclease at low and high salt concentrations. The RNA is in part liberated from the complex during purification over several cycles of equilibrium centrifugation in dye-buoyant density and Cs(2)SO(4) gradients. Analysis in the latter gradients reveals at least four classes of virus-specific nucleic acid: (i) RNA loosely bound and released during purification, (ii) and (iii) two distinct classes of RNA-DNA complexes with different DNA/RNA ratios, and (iv) DNA apparently not associated with RNA. The size of the RNA molecules is large but varying in the different classes of complexes. The biological function of these complexes is still uncertain, but they may be transcription complexes.