Size and distribution of SV 40 DNA Sequences covalently linked with the DNA of permissive mammalian cells.

CV-1 cells productively infected with SV 40 contain viral DNA which is covalently linked with the host cell DNA. These linear duplex viral-host DNA molecules are replicated during the infectious cycle. They can be selectively isolated and purified by two successive cycles of DNA-DNA hybridization and elution steps using first CV-1 cell and then SV 40-DNA immobilized on filters. In an attempt to clarify the nature of the host DNA sequences neighbouring the viral DNA it was found that reiterated host DNA must be within the range of 800 bases from the viral sequences. Reassociation kinetics and treatment of the reassociated viral-host DNA sequences with single strand-specific S1 nuclease have shown that unique host DNA sequences are always present in close neighbourhood of the viral DNA. Most of the SV 40 DNA sequences are probably intergrated as fragments of subgenomic length.