title: Temperature-sensitive mutants isolated from L cells persistently infected with Newcastle disease virus.
abstract: Virus mutants (NDV(pi)) isolated from L cells persistently infected with the Herts strain of Newcastle disease virus have been previously reported by this laboratory to differ from the wild-type virus (NDV(o)) in several physical and biological properties. It has now been determined that, in addition to these differences, the NDV(pi) mutants are also spontaneously selected temperature-sensitive mutants. The temperature sensitivity of 10 NDV(pi) clones was confirmed by temperature inhibition, plaquing efficiency, and single-cycle yield experiments. The cut-off temperature, at which more than 90% of virus replication is inhibited was between 41 and 42 C. All 10 NDV(pi) clones were also found to be defective in virus-specific ribonucleic acid (RNA) synthesis in infected chick embryo cells at 42 C and are tentatively classified as RNA(-). The possible relationships of the temperature sensitivity, the other NDV(pi) properties, and the maintenance of the persistently infected state are discussed.
mesh_terms: D000818:Animals; D002460:Cell Line; D002642:Chick Embryo; D002999:Clone Cells; D006387:Hemagglutination, Viral; D007739:L Cells / Q000382:microbiology*; D009154:Mutation; D009439:Neuraminidase / Q000032:analysis; D009522:Newcastle disease virus / Q000145:classification* / Q000302:isolation & purification / Q000378:metabolism; D010641:Phenotype; D012367:RNA, Viral / Q000096:biosynthesis; D013696:Temperature; D014461:Ultracentrifugation; D014779:Virus Replication
chemical_list: D012367:RNA, Viral; D009439:Neuraminidase