Construction and analysis of viable deletion mutants of simian virus 40

Viable mutants of simian virus 40 (SV40), with deletions ranging in size from 15 to 200 base pairs, have been obtained by infecting CV 1P cells with circularly permuted linear SV40 DNA. The linear DNA was produced by cleavage of closed circular DNA with DNase I in the presence of Mn²⁺, followed, in some cases, by mild digestion with λ 5' exonuclease. The SV40 map location and the size of each deletion were determined by using the S1 nuclease mapping procedure (Shenk et al., 1975) and the change in the size of fragments produced by Hind II+III endonuclease cleavage. Deletions in at least three regions of the SV40 chromosome have slight or no effect on the rate or yield of viral multiplication and on viral induced cellular transformation. These regions are located at the following coordinates on the SV40 physical map: 0.17 to 0.18; 0.54 to 0.59; and 0.68 to 0.74.