title: Characterization of a mutant of the Prague strain of Rous sarcoma virus inducing fusiform transformation of avian fibroblasts in vitro.
abstract: The DNA as isolated from duck fibroblasts transformed by a duck-adapted Prague strain of Rous sarcoma virus and used for transfection. Transformed recipient BLEF and DEF cultures exhibited considerable morphological variability. The virus designated daPR-RSV-C morphf was obtained from the culture with fusiform transformation and cloned. The virus retained the ability to induce fusiform transformation, even after 20 passages on chicken fibroblasts. There was a good correlation between focus forming activity of the virus and its tumorigenicity in chickens. The frequency of morphf mutation to another phenotype was less than 10(-3) in cloned virus. Foreign avian embryonic cells transformed by this virus clone had a similar morphological appearance as transformed chicken cells. The clone also retained two additional non-conditional markers - subgroup C specificity and the ability to replicate efficiently in duck cells ("duck adaptation"). Freshly obtained cloned virus was found not to contain a transformation-defective mutant. Such a mutant occurred in the second passage of the virus of DEF where the mutant was isolated. Inoculation of the td mutant into Brown Leghorn embryos gave rise to a sarcoma in one of the 36 examined chickens. However, no transforming virus was detected in the sarcoma. SDS-polyacrylamide gel electrophoresis showed that cloned daPR-RSV-C morphf contained only genomic RNA; its molecular weight 3.08 X 10(6) daltons corresponded to the molecular weight of a non-defective PR-RSV-C used as control.
mesh_terms: D000818:Animals; D001358:Avian Sarcoma Viruses / Q000235:genetics*; D002472:Cell Transformation, Viral; D002645:Chickens; D004372:Ducks; D005814:Genes, Viral; D008970:Molecular Weight; D009154:Mutation; D012367:RNA, Viral / Q000235:genetics; D012513:Sarcoma, Experimental / Q000235:genetics; D014779:Virus Replication
chemical_list: D012367:RNA, Viral