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A biochemical and genetic analysis of mammalian RNA-containing sarcoma viruses
Abstract:
Current studies have shown that all mammalian sarcoma-producing viruses, whether isolated from laboratory experiments of naturally occurring tumors, are deletion mutants of replicating mammalian type C viruses. Nonproducer cells transformed by any of these sarcoma viruses contain RNA homologous to mammalian leukemia viruses, even though the cells contain no known proteins currently coded for by the mammalian leukemia virus. This mammalian leukemia virus information (FT-) is a genetically stable part of the mammalian sarcoma viruses (FT+). Second, another component in the Kirsten and Harvey sarcoma viruses can be identified in addition to this leukemia virus information for the homologous leukemia virus; at least part of the additional information came from rat type C viruses from the animals in which the sarcoma viruses were isolated. This indicates that these two mammalian sarcoma viruses are recombinants between mouse leukemia virus and genetic information in rat cells and suggests that the process of formation of the sarcoma virus is analogous to transduction of information in bacteriophage. Third, the Kirsten sarcoma virus seems to have a third component in it separate from either the mouse leukemia virus or rat leukemia virus information. Fourth, and FT+ leukemia virus isolated from mice, the Abelson leukemia virus which causes as B-cell leukemia, is also defective and can be shown to have information homologous to Moloney leukemia virus. Fifth, in the feline sarcoma virus, feline leukemia information can be detected, but information for the other cat virus, RD-114, cannot be detected. Finally, mutants of Kirsten sarcoma virus temperature sensitive for the maintenance of transformation have been isolated, and out of ten such mutants, thus far no complementation has been observed.
Insights
Mammalian sarcoma viruses are deletion mutants of type C viruses, containing leukemia virus RNA. Some sarcoma viruses are recombinants, incorporating genetic information from rat cells, suggesting a transduction-like formation process.
Area of Science:
- Virology
- Oncology
- Molecular Biology
Background:
- Mammalian sarcoma viruses are deletion mutants of replicating type C viruses.
- Transformed cells contain RNA homologous to mammalian leukemia viruses, but lack viral proteins.
Purpose of the Study:
- To investigate the genetic composition and origin of mammalian sarcoma viruses.
- To understand the formation process of sarcoma viruses, potentially analogous to transduction.
Main Methods:
- Analysis of RNA homology in transformed nonproducer cells.
- Identification of genetic components within Kirsten and Harvey sarcoma viruses.
- Isolation and characterization of temperature-sensitive mutants of Kirsten sarcoma virus.
Main Results:
- Mammalian sarcoma viruses contain genetically stable leukemia virus information (FT-).
- Kirsten and Harvey sarcoma viruses are recombinants of mouse leukemia virus and rat type C viral information.
- Kirsten sarcoma virus possesses a third, distinct genetic component.
- Abelson leukemia virus contains information homologous to Moloney leukemia virus.
- Feline sarcoma virus contains feline leukemia information but not RD-114 information.
- No complementation observed among temperature-sensitive Kirsten sarcoma virus mutants.
Conclusions:
- Mammalian sarcoma viruses are complex genetic entities, often resulting from recombination events.
- The formation of sarcoma viruses may involve a process similar to bacteriophage transduction.
- Further research is needed to fully elucidate the genetic makeup and functional mechanisms of these viruses.