Isolation of double lysogens from 3T3 cells transformed by plaque morphology mutants of SV40

Abstract

Simian virus 40 (SV40) rescued from 3T3 lines transformed independently by fuzzy plaque strain, SV40 (mKS-U4), and small-clear plaque strain, SV40 (mKS-U88), resembled the virus used to initiate the transformation. When a mixture of the two viruses was used for transformation, both plaque types could be rescued. Two clonal lines, after fusion with CV-1 cells, yielded both plaque types of infectious centers, and a third clonal line, 3T3(4-88)G-1, yielded fuzzy and small-clear plaque types of infectious centers plus large-clear infectious centers resembling "wild-type" SV40 clone 307L. Two secondary and 14 tertiary clones of 3T3(4-88)G-1 were isolated, all of which yielded fuzzy plaque type and clear infectious centers after fusion with CV-1 cells. When these infectious centers were picked and replated on CV-1 cells, the fuzzy and small-clear plaque types of SV40, as well as a large-clear plaque type resembling parental SV40, were isolated.