Viral nucleic acid sequences in transformed cells

Specific fragments of Adenovirus 5 DNA were produced by digestion of intact, 32P-labeled viral DNA with restriction endonucleases Eco R1 and and Hpa 1. The kinetics of renaturation of each fragment and of complete Adenovirus 5 DNA were measured in the presence of DNA extracted from four lines of Adenovirus 5-transformed rodent cells and from nontransformed control cells. All four transformed cell lines contained sequences homologous to the Hpa 1 fragment comprising the left 4% of the viral genome, but varied in the other Adenovirus 5 DNA sequences which were present: three lines of transformed cells contain segments of DNA extending from the left hand end to points 35, 40, and 12% along the viral genome and carry no other Adenovirus 5 DNA sequences. The fourth line also contains sequences homologous to the left half of the viral genome, but these could not be precisely defined. Therefore, the gene(s) encoded by the left end of Adenovirus 5 DNA must specify any viral gene functions expressed in transformed cells. Separated strands of the three Eco R1 fragments and certain Hpa 1 fragments of 32P-labeled Adenovirus 5 DNA were hybridized with unlabeled, cytoplasmic RNA extracted from each of the four transformed cell lines. In each case, about 10% only of the r strand sequences of the largest Eco R1 fragment were complementary to transformed cell RNA. These sequences have been mapped to the left end of the viral genome using Hpa 1 fragment strands. The same sequences are shown to be expressed as mRNA during the early phase of an Adenovirus 5 lytic infection.