Recovery Of Sv40 Virus With Genetic Markers Of Original Inducing Virus From Sv40-Transformed Mouse Cells

Cells from three different mouse strains were transformed in vitro with 2 mutants of SV40 as well as with wild-type virus. SV40 virus could be recovered from transformed AL N and AKR cells by cocultivation with susceptible cells, but virus production occurred much sooner when cells were allowed to form heterokaryons with UV-inactivated Sendai virus. 3T3 transformed cells which did not yield virus by simple cocultivation did yield virus by the cell-fusion technique. SV40 virus recovered from transformed cells was examined and compared with the original transforming virus for three genetic markers: (a) plaque size in primary AGMK, (b) growth at 40°, and (c) plating efficiency and plaque size in an established AGMK cell line, CV-1. In all cases, the virus recovered possessed the markers of the original parental virus.