title: Characterization of human TK- cell lines transformed to a TK+ phenotype by herpes simplex virus type 2 DNA.
abstract: Human TK- cells carrying the HSV-2 TK gene as a result of transformation with virus DNA express a TK activity of virus origin and maintain the TK+ phenotype when grown in HAT medium. Under non-selective conditions, however, reversion to a TK- phenotype occurs with a significant frequency characteristic of each transformed line. Once reversion has occurred the TK- phenotype appears to be stable, since only very rare instances of TK- to TK+ reversion have been observed. TK- revertants were susceptible to re-transformation by virus DNA, but no reactivation of a silent virus TK gene could be obtained by superinfecting them with a TK- virus mutant. The data presented are consistent with the hypothesis that acquisition of the TK- phenotype is brought about by loss of the virus sequences coding for TK.
mesh_terms: D002460:Cell Line; D002472:Cell Transformation, Viral; D004279:DNA, Viral / Q000235:genetics*; D005814:Genes, Viral; D009154:Mutation; D010641:Phenotype; D018139:Simplexvirus / Q000235:genetics*; D013937:Thymidine Kinase / Q000096:biosynthesis*
chemical_list: D004279:DNA, Viral; D013937:Thymidine Kinase