State of the viral DNA in rat cells transformed by polyoma virus. I. Virus rescue and the presence of nonintergrated viral DNA molecules

@article{Prasad1976StateOT,
  title={State of the viral DNA in rat cells transformed by polyoma virus. I. Virus rescue and the presence of nonintergrated viral DNA molecules},
  author={I Prasad and Dimitris Zouzias and Claudio Basilico},
  journal={Journal of Virology},
  year={1976},
  volume={18},
  pages={436 - 444}
}
The interaction of polyoma virus with a continuous line of rat cells was studied. Infection of these cells with polyoma did not cause virus multiplication but induced transformation. Transformed cells did not produce infectious virus, but in all clones tested virus was rescuable upon fusion with permissive mouse cells. Transformed rat cells contained, in addition to integrated viral genomes, 20 to 50 copies of nonintegrated viral DNA equivalents per cell (average). "Free" viral DNA molecules… Expand
State of the viral DNA in rat cells transformed by polyma virus. II. Identification of the cells containing nonintegrated viral DNA and the effect of viral mutations
TLDR
The results suggest that the presence of free viral DNA in polyoma-transformed rat cells is caused by a spontaneous induction of viral DNA replication, occurring with low but constant probability in the transformed cell population, and that the free viralDNA molecules originate from the integrated ones, probably through a phenomenon of excision and limited replication. Expand
Multiple Free Viral DNA Copies in Polyoma Virus-Transformed Mouse Cells Surviving Productive Infection
TLDR
Mouse 3T6 cells were infected with polyoma virus at high multiplicity, and survivors were isolated and found to be resistant to a second infection, but in some clones viral functions could at least be partially expressed during reinfection, as judged from a stimulation of nuclear tumor antigen expression. Expand
Relationship between integrated and nonintegrated viral DNA in rat cells transformed by polyoma virus
TLDR
The hypothesis that the free DNA derives from the integrated form through a mechanism of homologous recombination leading to excision and limited replication is supported. Expand
Loss of integrated viral DNA sequences in polyoma-transformed cells is associated with an active viral A function
TLDR
Results indicate that in polyoma-transformed rat cells, loss of integrated viral DNA can occur at a rather high rate, producing (at least in some cases) cells which have reverted partially or completely to a normal phenotype. Expand
State and organization of polyoma virus DNA sequences in transformed rat cell lines
TLDR
Polyoma virus-transformed rat cell lines were isolated as colonies growing in agar after infection of F2408 cells with low multiplicities of wild-type virus, and both free and apparently integrated viral DNA were found. Expand
Polyoma virus-specific RNA synthesis in an inducible line of polyoma virus-transformed rat cells
TLDR
It is concluded that the induction of viral DNA replication in LPT cells is not determined at the level of mRNA synthesis, and the synthesis of both the early and the late RNA species was inhibited if viralDNA replication was blocked with 5-fluorodeoxyuridine. Expand
Free viral DNA in BK virus-induced hamster tumor cells
TLDR
The biological properties of nine clonal lines of BK virus-induced hamster tumor cells were studied, and the great majority of the viral DNA molecules appeared to be present as free (nonintegrated) molecules. Expand
Nonintegrated viral DNA in rat cells doubly transformed by SV40 and polyoma virus.
TLDR
Rat F2408 cells transformed by polyoma virus contain, in addition to integrated viral genomes, a small number of nonintegrated viral DNA molecules, which can be detected in these cells in a “free” state. Expand
Polyoma large T antigen regulates the integration of viral DNA sequences into the genome of transformed cells
TLDR
Results indicate that polyoma DNA sequences can integrate into the host genome in tandem and nontandem arrangements and that the former mode of integration increases the efficiency of transformation and is promoted by large T antigen. Expand
Untransformed rat cells containing free and integrated dna of a polyoma nontransforming (Hr-t) mutant
TLDR
Results show that integration of viral sequences per se or the presence of the 100K large T antigen is not sufficient for the transformed phenotype to be expressed, and strongly suggest that Py-induced transformation is mediated by the 55K middle and/or 22K small T antigens. Expand
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