title: Temperature-sensitive simian virus 40 mutant defective in a late function.
abstract: A temperature-sensitive simian virus 40 (SV40) mutant, tsTNG-1, has been isolated from nitrosoguanidine-treated and SV40-infected African green monkey kidney (CV-1) cultures. Replication of virus at the nonpermissive temperature (38.7 C) was 3,000-fold less than at the permissive temperature (33.5 C). Plaque formation by SV40tsTNG-1 deoxyribonucleic acid (DNA) on CV-1 monolayers occurred normally at 33.5 C but was grossly inhibited at 38.7 C. The time at which virus replication was blocked at 38.7 C was determined by temperature-shift experiments. In shift-up experiments, cultures infected for various times at 33.5 C were shifted to 38.7 C. In shift-down experiments, cultures infected for various times at 38.7 C were shifted to 33.5 C. All cultures were harvested at 96 hr postinfection (PI). No virus growth occurred when the shift-up occurred before 40 hr PI. Maximum virus yields were obtained at 96 hr PI when the shift-down occurred at 66 hr, but only about 15% of the maximum yield was obtained when the shift-down occurred at 76 hr PI. These results indicate that SV40tsTNG-1 contains a conditional lethal mutation in a late viral gene function. Mutant SV40tsTNG-1 synthesized T antigen, viral capsid antigens, and viral DNA, and induced thymidine kinase activity at either 33.5 or 38.7 C. The properties of the SV40 DNA synthesized in mutant-infected CV-1 cells at 33.5 or 38.7 C were very similar to those of SV40 DNA made in parental virus-infected cells, as determined by nitrocellulose column chromatography, cesium-chloride-ethidium bromide equilibrium centrifugation, and by velocity centrifugation in neutral sucrose gradients. Mutant SV40tsTNG-1 enhanced cellular DNA synthesis in primary cultures of mouse kidney cells at 33.5 and 38.7 C and also transformed mouse kidney cultures at 36.5 C. SV40tsTNG-1 was recovered from clonal lines of transformed cells after fusion with susceptible CV-1 cells and incubation of heterokaryons at 33.5 C, but not at 38.7 C.
mesh_terms: D000818:Animals; D002460:Cell Line; D002499:Centrifugation, Density Gradient; D003168:Complement Fixation Tests; D046508:Culture Techniques; D004279:DNA, Viral / Q000096:biosynthesis; D005455:Fluorescent Antibody Technique; D000882:Haplorhini; D007668:Kidney; D051379:Mice; D009154:Mutation; D010222:Parainfluenza Virus 1, Human; D013539:Simian virus 40 / Q000201:enzymology / Q000254:growth & development* / Q000276:immunology; D013696:Temperature; D013937:Thymidine Kinase / Q000378:metabolism; D014170:Transformation, Genetic; D014316:Tritium; D014779:Virus Replication
chemical_list: D004279:DNA, Viral; D014316:Tritium; D013937:Thymidine Kinase