Studies on a Virogenic Clone of SV 40-transformed Rabbit Cells Using Cell Fusion and in situ Hybridization

Abstract

Summary A clone of baby rabbit kidney cells transformed with SV 40 virus was found to be releasing virus at the rate of about 1 infectious unit per 104 cells per day. Virus antigen was detected in between 1 in 103 and 1 in 104 cells. In situ hybridization with radioactive SV 40 complementary RNA revealed that about 3% of the transformed cells were producing virus DNA. When the transformed cells were fused with permissive cells and incubated in anti-SV 40 serum between 2% and 8% of the heterokaryons formed produced SV 40 virus. A model is proposed according to which the cells in this clone, and possibly other transformed clones, may exist in one of three states: (A) the commonest state, in which virus DNA is not replicable autonomously; (B) a state in which virus DNA can be replicated autonomously, but late virus proteins are not made; and (C) a state in which complete virus can be synthesized.