Cytoplasmic DNA synthesis induced by RNA tumor viruses

Infection of mouse embryo cells with two strains of murine sarcoma virus and one strain of murine leukemia virus was followed rapidly by synthesis of DNA in the cytoplasm. Persistently infected cells have not shown such synthesis, and ultraviolet-irradiated virus did not induce DNA synthesis. This new DNA presumably represents an intermediate in the virus replication cycle specified by the virion DNA polymerase(s). Failure to observe cytoplasmic DNA synthesis in persistently infected cells suggests, in keeping with the results of inhibitor experiments, that the new "viral" DNA becomes associated with cellular DNA in some form of stable interaction.

Specificity of the DNA product of the C-type virus RNA-dependent DNA polymerase

The specificity of the DNA product of the RNA-dependent DNA polymerase found in C-type virions was analyzed by reciprocal hybridization with RNA from viruses of mouse, hamster, cat, and viper. These tests revealed a clear species specificity for the DNA product with no detectable interspecies hybridization.

DNA polymerase activity associated with RNA tumor viruses

C-type RNA viruses, originating in mouse, cat, hamster, and viper, catalyze the synthesis of DNA from its constituent deoxyribonucleoside triphosphates. Both the rate and extent of the reaction were significantly enhanced by brief treatment of the intact virus with ether. A proportion of the newly synthesized DNA was associated with virions when intact virus was used as template; this was not the case with ether-treated virus. In both cases, DNA extracted from the reaction mixture sedimented slowly, at about 2-4 S.

Electrophoresis of adenovirus-specified thymidine kinase

Stimulation of thymidine kinase (TK) activity occurs after abortive or productive infection with human adenoviruses. Striking changes in TK electrophoretic profile accompany this stimulation.