DNA of a human hepatitis B virus candidate

J Virol. 1974 Aug;14(2):384-91. doi: 10.1128/JVI.14.2.384-391.1974.


Particles containing DNA polymerase (Dane particles) were purified from the plasma of chronic carriers of hepatitis B antigen. After a DNA polymerase reaction with purified Dane particle preparations treated with Nonidet P-40 detergent, Dane particle core structures containing radioactive DNA product were isolated by sedimentation in a sucrose density gradient. The radioactive DNA was extracted with sodium dodecyl sulfate and isolated by band sedimentation in a preformed CsCl gradient. Examination of the radioactive DNA band by electron microscopy revealed exclusively circular double-stranded DNA molecules approximately 0.78 mum in length. Identical circular molecules were observed when DNA was isolated by a similar procedure from particles that had not undergone a DNA polymerase reaction. The molecules were completely degraded by DNase 1. When Dane particle core structures were treated with DNase 1 before DNA extraction, only 0.78-mum circular DNA molecules were detected. Without DNase treatment of core structures, linear molecules with lengths between 0.5 and 12 mum, in addition to the 0.78-mum circles were found. These results suggest that the 0.78-mum circular molecules were in a protected position within Dane particle cores and the linear molecules were not within core structures. Length measurements on 225 circular molecules revealed a mean length of 0.78 +/- 0.09 mum which would correspond to a molecular weight of around 1.6 x 10(6). The circular molecules probably serve as primer-template for the DNA polymerase reaction carried out by Dane particle cores. Thermal denaturation and buoyant density measurements on the Dane particle DNA polymerase reaction product revealed a guanosine plus cytosine content of 48 to 49%.

MeSH terms

  • Centrifugation, Density Gradient
  • Cytosine / analysis
  • DNA Nucleotidyltransferases / metabolism
  • DNA, Circular / analysis
  • DNA, Viral / analysis*
  • DNA, Viral / biosynthesis
  • Guanosine / analysis
  • Hepatitis B virus / analysis*
  • Hepatitis B virus / enzymology
  • Hot Temperature
  • Microscopy, Electron
  • Molecular Weight
  • Nucleic Acid Denaturation
  • Nucleotides / metabolism
  • Tritium


  • DNA, Circular
  • DNA, Viral
  • Nucleotides
  • Tritium
  • Guanosine
  • Cytosine
  • DNA Nucleotidyltransferases