Characterization of an endonuclease associated with simian virus 40 virions

An endonucleolytic activity associated with purified simian virus 40 (SV40) virions has been found. The enzyme is present in virions prepared from a number of different host lines. The enzyme is present in all early and late temperature-sensitive mutants examined. Some aspects of the endonucleolytic activity have been examined with SV40 deoxyribonucleic acid as substrate.