Helper-independent transformation by unintegrated Harvey sarcoma virus DNA.
We have studied the unintegrated infectious DNA of Harvey sarcoma virus (Ha-SV) and Moloney leukemia virus (Mo-MuLV). The source of infectious viral DNA was the Hirt supernatant fraction from cells acutely infected with Ha-SV and Mo-MuLV. To obtain a direct quantitative assay for infectious viral DNA, recipient mouse cells were first exposed to calcium phosphate-precipitated viral DNA and then treated with dimethyl sulfoxide. Infectivity was monitored by focus formation for Ha-SV and XC plaque formation for Mo-MuLV. The viral DNA titration pattern followed single-hit kinetics for both foci and plaques, indicating that a single molecule carried information for each function. Focus-forming and plaque-forming activity were present in different molecules, since these two biological activities could be separated from each other by agarose gel electrophoresis. The focus-forming molecule was linear DNA with a molecular weight of about 4 x 10(6) daltons. The focus-forming activity of the viral DNA was sensitive to EcoRI and resistant to XhoI restriction endonucleases, whereas the plaque-forming activity was resistant to EcoRI and sensitive to XhoI. The generation of helper-independent foci indicates that Ha-SV DNA can transform mouse cells in the absence of helper virus or its proteins.
D002460:Cell Line; D002472:Cell Transformation, Viral; D004262:DNA Restriction Enzymes / Q000494:pharmacology; D004279:DNA, Viral / Q000235:genetics*; D017988:Gammaretrovirus / Q000235:genetics*; D006863:Hydrogen-Ion Concentration; D008979:Moloney murine leukemia virus / Q000235:genetics*; D009053:Sarcoma Viruses, Murine / Q000235:genetics*; D014162:Transfection; D010948:Viral Plaque Assay
D004279:DNA, Viral; D004262:DNA Restriction Enzymes