Detection of viral markers and incomplete viral genome rescue from ASV transformed rodent cells.
Two non-virogenic rat cell lines TWERC and FR transformed with PR-RSV and FSV, respectively, were analyzed. Both these cell lines contained vRNA, but only in TWERC cells was the major viral polypeptide p27 synthetized. Transforming virus can be rescued from both cell lines only after fusing them with chicken fibroblasts preinfected with avian leukosis viruses of subgroup A, C, D, F and both td mutants of PR-RSV-C and B77-C. Similarly, virus was rescued in experiments in which QEF infected with RAV-1 or DEF infected with td B77-C or RAV-61 were employed as indicator cells. On the contrary, DEF infected with MuLV-X and probably also myeloblasts transformed with AMV were not active in virus rescue. No virus rescue was observed in long-term passaged non-virogenic mouse cell lines RVP(3) and RVA(4), using the same spectrum of helper virus-infected avian cells, which gave positive virus rescue with the non-virogenic rat cells. In both mouse cell lines, also no vRNA or p27 was detected. In 13 independent experiments in which TWERC cells were fused with RAV-1-infected BLEF, rescued viruses were isolated. Using two independent host-range tests, only the subgroup A specificity was detected in the viral isolates tested, which is the subgroup of RAV-1 used as a helper virus. These and other experiments indicate that ASV rescued from TWERC cells acquire in a vast majority of cases the env gene product only from the helper virus which suggests that the viral genome(s) present in TWERC cells is (are) vastly deficient in the env gene. The specificity of helper virus and indicator cells both required for the virus induction from some nonvirogenic cells and the possibility of the loss of viral genome from other non-virogenic cell lines are discussed.
D000818:Animals; D001358:Avian Sarcoma Viruses; D002459:Cell Fusion; D002460:Cell Line; D002472:Cell Transformation, Viral; D002642:Chick Embryo; D005814:Genes, Viral; D006378:Helper Viruses; D051379:Mice; D012367:RNA, Viral / Q000032:analysis*; D051381:Rats; D014764:Viral Proteins / Q000032:analysis*
D012367:RNA, Viral; D014764:Viral Proteins