title: In vitro activation, infectivity, and production of endogenous type-C virus from OM rats.
abstract: T24C, a continuous cell line derived from the pooled thymic tissue of normal inbred OM rats, spontaneously produced type-C virus. The virus genome was expressed cyclically. The amount of RNA-dependent DNA polymerase (RDP) and the number of 1.14 g dense particles/ml fluctuated simultaneously with cultivation. The released virus, RPT24C, did not infect cell lines from the rat, mouse, dog, or human. T31, also a rat thymus line, during its 2.5 years of cultivation did not produce type-C virus. Cocultivation with potentially permissive lines did not rescue any virus. 5-lodo-2'-deoxyuridine treatments at earlier passages yielded negative results. Chemical treatment at passages 111, 116, 123, and 128 yielded varying amounts of 3H-uridine incorporation at a sucrose density of 1.14 g/ml. Enzyme assays on chemically treated T31 cultures tested at passage 111 showed a small but transient burst of RDP activity. T31-B, a subline of T31, which was frozen and thawed once, released rat type-C virus spontaneously at passage 56. Two additional sublines of T31 (NI-T31 and NII-T31) were maintained for 2.5 years in culture without any cell-dispersing treatment. NI-T31, but not NII-T31, spontaneously released type-C virus. Once induced, the type-C viruses from T31-B and NI-T31 were continuously produced.
mesh_terms: D000818:Animals; D002460:Cell Line; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D006378:Helper Viruses; D007065:Idoxuridine / Q000494:pharmacology; D007181:Inclusion Bodies, Viral / Q000648:ultrastructure; D012194:RNA-Directed DNA Polymerase / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012190:Retroviridae / Q000187:drug effects / Q000254:growth & development / Q000302:isolation & purification*; D013950:Thymus Gland / Q000378:metabolism / Q000382:microbiology* / Q000648:ultrastructure; D014529:Uridine / Q000378:metabolism; D014779:Virus Replication
chemical_list: D012194:RNA-Directed DNA Polymerase; D007065:Idoxuridine; D014529:Uridine; D004121:Dimethyl Sulfoxide