Characterization of a new virus from Mus cervicolor immunologically related to the mouse mammary tumor virus
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Abstract:
A virus, similar to the murine mammary tumor viruses (MuMTV) of the laboratory mouse Mus musculus, was identified in the milk of M. cervicolor popaeus mice. The virus was morphologically indistinguishable from the type-B MuMTV and was thus termed MC-MTV. Radioimmunoassays for the 52,000-dalton major envelope glycoprotein and the 28,000-dalton major internal protein of MuMTV demonstrated that MC-MTV shared some antigenic determinants with both of these MuMTV proteins. This reactivity was clearly different, however, from that observed with all MuMTV tested from M. musculus. MC-MTV had a density of 1.16 g/ml in sucrose and a virion-associated DNA polymerase with a divalent cation preference for Mg2+ over Mn2+. Radioimmunoassays clearly differentiated MC-MTV from the other viruses previously identified from M. cervicolor, i.e., M432, CERV-CI, and CERV-CII. These studies thus identified the first virus from another species that is immunologically related to the MuMTV of M. musculus. Particles similar to MC-MTV were also observed in a spontaneous M. cervicolor popaeus mammary tumor.
Insights
A novel virus, MC-MTV, was found in wild mice and is immunologically related to murine mammary tumor viruses (MuMTV). This discovery marks the first related virus identified in a species other than the laboratory mouse.
Area of Science:
- Virology
- Oncology
- Mammalian Genetics
Background:
- Murine mammary tumor viruses (MuMTV) are retroviruses primarily studied in laboratory mice (Mus musculus).
- These viruses are associated with mammary tumors and are transmitted through milk.
- Understanding MuMTV diversity is crucial for cancer research.
Purpose of the Study:
- To identify and characterize viruses similar to MuMTV in wild mouse species.
- To determine the immunological relationship between a newly identified virus and MuMTV.
- To investigate the presence of such viruses in mammary tumors of wild mice.
Main Methods:
- Morphological analysis of viral particles.
- Radioimmunoassays (RIAs) targeting MuMTV envelope and internal proteins.
- Density gradient centrifugation.
- Assay of virion-associated DNA polymerase activity.
- Comparison with previously identified viruses from the same wild mouse species.
Main Results:
- A virus, MC-MTV, morphologically similar to type-B MuMTV, was isolated from the milk of M. cervicolor popaeus mice.
- MC-MTV shared some antigenic determinants with MuMTV proteins but differed from MuMTV strains from M. musculus.
- MC-MTV exhibited a density of 1.16 g/ml and a Mg2+-dependent DNA polymerase.
- RIAs distinguished MC-MTV from other M. cervicolor viruses (M432, CERV-CI, CERV-CII).
- Virus-like particles resembling MC-MTV were found in a spontaneous M. cervicolor popaeus mammary tumor.
Conclusions:
- MC-MTV represents the first identified virus from a species other than Mus musculus that is immunologically related to MuMTV.
- The findings suggest a broader host range and evolutionary history for MuMTV-like viruses.
- The presence of MC-MTV in a mammary tumor warrants further investigation into its oncogenic potential in wild mice.