Introduction of Pyrimidine Dimers Into Different Intracellular Forms of Simian Virus 40

We examined the production of pyrimidine dimers by UV radiation in different intracellular forms of simian virus 40 DNA. Virus and chromatin or previrions were selectively labeled with [l4C]‐thymidine and [3H]‐thymidine, respectively, in the same monolayer of infected cells. Viral DNA was extracted immediately after irradiation, and pyrimidine dimers were detected as sites sensitive to the UV‐endonuclease encoded by bacteriophage T4. No difference in the number of dimers introduced into chromatin, previrions. or virions was detected.