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Transduction of proto-src sequences in tissue culture by a molecular clone of transformation-defective Rous sarcoma

W Phares1

  • 1Department of Molecular Biology, University of California, Berkeley 94720.

Journal of Virology
|December 1, 1988
PubMed

Insights

Nondefective Rous sarcoma virus (ndRSV) can spontaneously arise from transformation-defective RSV. This occurs through homologous recombination between viral and cellular proto-src genes, with transduction frequencies observed between 0.4 x 10(7) and 1.6 x 10(7) infected cells.

Area of Science:

  • Molecular biology
  • Virology
  • Genetics

Background:

  • Rous sarcoma virus (RSV) is a retrovirus known for its ability to transform cells.
  • Transformation-defective RSV mutants are typically unable to induce tumors or cause rapid cell transformation.
  • The spontaneous generation of nondefective RSV from defective variants suggests a mechanism for genetic repair or acquisition.

Purpose of the Study:

  • To investigate the mechanism by which transformation-defective Rous sarcoma virus (RSV) can generate nondefective (nd) RSV.
  • To determine if homologous recombination with cellular proto-src is involved in the generation of ndRSV.
  • To quantify the frequency of this genetic restoration event.

Main Methods:

  • Infection of cells in tissue culture with a molecular clone of transformation-defective RSV.
  • Southern blot analysis of extrachromosomal, virus-specific DNA from independent ndRSV isolates.
  • Fluctuation analysis to estimate the frequency of transduction.

Main Results:

  • Three independent isolates of ndRSV were generated from cells infected with transformation-defective RSV.
  • Southern analysis confirmed the restoration of an isogenic src gene in these ndRSV isolates.
  • Homologous recombination between the viral genome and cellular proto-src was identified as the mechanism for src restoration.
  • The frequency of transduction was estimated to be between 1 per 0.4 x 10(7) and 1.6 x 10(7) infected cells.

Conclusions:

  • Transformation-defective RSV can spontaneously revert to a nondefective form in tissue culture.
  • This reversion occurs via homologous recombination with the cellular proto-src gene.
  • The study provides quantitative data on the frequency of this genetic event in RSV replication.

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