Abstract
The distribution of DNA topoisomers in intracellular simian virus 40 DNA was analyzed by gel electrophoresis. The results suggested that DNA extracted from 70S chromatin had a different superhelical density distribution as compared with the DNA obtained from virions or virion assembly intermediates. The heterogeneity of simian virus 40 viral DNA superhelical density at a late time after infection was partly due to increased virion production and partly due to the intrinsic heterogeneity of the superhelical density of DNA extracted from virions. Using two-dimensional gel electrophoretic analysis we also showed that simian virus 40 DNA templates used for DNA replication have a higher average superhelical density than the bulk of intracellular viral DNA.