Abstract
Summary
Attempts were made to learn if SV40-transformed cells are resistant to super-transformation by infecting SV40-trans-formed clones of 3T3 with SV40. No alteration of growth properties was detected after SV40 infection of four cloned lines of SV40-transformed 3T3 that had stable low saturation densities. In contrast, SV40 infection of polyoma-transformed 3T3 having comparable saturation densities yielded easily detectable double transformants. Two lines of 3T3, which had been transformed by UV-inactivated SV40 and did not release virus upon fusion with permissive cells, were super-infected with SV40. After dilution of residual virus by cell growth, the superinfecting virus could not be recovered from either of the cell lines upon fusion with permissive (GMK) cells. Two lines transformed by a temperature sensitive large plaque mutant of SV40 were infected with temperature resistant small and minute plaque mutants. Fusion of the cells with GMK at the permissive temperature was effective in releasing the initial transforming mutant from both clones, but no superinfecting (temperature resistant) virus could be detected at either the permissive or nonpermissive temperature. We conclude that if super transformation occurs with SV40 it is an uncommon event, for superinfecting virus could not be recovered, nor could cells with altered growth properties be detected.
Get full access to this article
View all access options for this article.