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Characterization of mouse mammary tumor viruses propagated in heterologous cells
Abstract:
Mouse mammary tumor viruses (MMTV) from three different strains of mice have been used to establish productive infections in feline and mink cell lines. The virions that are released by these cells compete completely in a radioimmunoassay for the major virion surface glycoprotein of MMTV (gp52), thus demonstrating that antigenic determinants of gp52 are viral coded. Competitive molecular hybridization studies have shown that the 60 to 70 S RNA's of MMTV's propagated in feline cells contain all the nucleic acid sequences found in 60 to 70 S RNA from MMTV synthesized by murine cells. The virion buoyant densities in sucrose and cesium chloride, virion sedimentation coefficient, divalent cation requirement of the virion DNA polymerase, and morphology of MMTV's synthesized in heterologous cells are similar to those of MMTV's grown in murine cells. Cultures of MMTV-infected feline cells have continuously released between 0.1 and 1.0 microgram of virus per 10(7) cells (75-sq cm flask) per day during the 60-week observation period. No detectable feline or murine type C viruses were produced by these cultures.
Insights
Mouse mammary tumor virus (MMTV) can infect feline and mink cells, producing infectious virions. These heterologously produced MMTV particles share key antigenic and genetic properties with those grown in mouse cells.
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Mouse mammary tumor virus (MMTV) is a retrovirus associated with mammary tumors in mice.
- Understanding MMTV replication and properties in different host cells is crucial for virological research.
Purpose of the Study:
- To investigate the productive infection of MMTV in heterologous feline and mink cell lines.
- To characterize the properties of MMTV produced in these non-murine cells.
Main Methods:
- Establishing productive MMTV infections in feline and mink cell lines.
- Radioimmunoassay to assess viral glycoprotein (gp52) antigenicity.
- Competitive molecular hybridization to analyze viral RNA sequences.
- Characterization of virion properties (buoyant density, sedimentation, DNA polymerase, morphology).
Main Results:
- Virions released from feline and mink cells contained MMTV gp52, indicating viral coding of antigenic determinants.
- MMTV RNA from feline cells contained all nucleic acid sequences of murine MMTV.
- MMTV produced in heterologous cells exhibited similar physical and biochemical properties to MMTV grown in murine cells.
- Continuous release of MMTV was observed for 60 weeks without detectable feline or murine type C viruses.
Conclusions:
- MMTV can productively infect feline and mink cells, yielding infectious virions.
- The antigenic and genetic characteristics of MMTV are conserved across these heterologous cell systems.
- This demonstrates the potential for studying MMTV in non-murine cell cultures.