Integration and transcription of virus DNA in herpes simplex virus transformed cell lines

The physical state of the HSV I DNA present in two biochemically transformed cell lines, a revertant line and a supertransformed cell line, was determined. These cells all contained fragments of the HSV genome and the transformed and supertransformed cell lines expressed virus thymidine kinase. It was found that the virus DNA in these cells was maintained in a complex state with approximately half of the HSV DNA present in a covalently integrated state and the other half in a non-integrated state. There was no major cell line difference in the distribution of integrated and non-integrated virus DNA. RNA transcripts representing 5% of the HSV I genome are present in each of these lines. This is more than is required to code for the virus thymidine kinase present in the transformed and supertransformed cell lines and suggests the presence of other virus proteins in these cells.