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RIII/Sa Mice with a High Incidence of Mammary Tumors Express Two Exogenous Strains and One Potential Endogenous Strain of Mouse Mammary Tumor Virus
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| Zeitschriftentitel: | Journal of Virology |
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| Personen und Körperschaften: | , , |
| In: | Journal of Virology, 78, 2004, 2, S. 1055-1062 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
American Society for Microbiology
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| Schlagwörter: |
| Zusammenfassung: | <jats:title>ABSTRACT</jats:title> <jats:p> The inbred mouse strain RIII has long been known for shedding large amounts of mouse mammary tumor virus (MMTV) particles in milk and for the development of hormone-dependent early mammary tumors at a very high incidence (>90%). We have established one RIII subline (RIII/Sa) that shows a pattern of virus expression and tumor incidence similar to that in RIII mice. In the present study, we analyzed the milk and mammary tumors of RIII/Sa mice for virus characterization by reverse transcriptase PCR (RT-PCR) cloning and sequencing of the open reading frame (ORF) of the MMTV long terminal repeats (LTRs). Our results show that these mice express a mixture of at least three different MMTV strains, two of which, designated here as RIII/Sa MMTV-1 and RIII/Sa MMTV-2, are exogenous. The third virus, RIII/Sa MMTV-3, appears to carry the signature of an endogenous provirus, <jats:italic>Mtv</jats:italic> - <jats:italic>17</jats:italic> . Similar studies done with the milk and mammary glands of another subline, RIIIS/J, revealed that they do not express MMTV in their milk. The RIII/Sa and RIIIS/J mice also exhibited differences in their endogenous proviral contents. Twelve spontaneously developed mammary tumors of RIII/Sa mice were examined for possible <jats:italic>Wnt</jats:italic> - <jats:italic>1</jats:italic> and/or <jats:italic>int</jats:italic> - <jats:italic>2</jats:italic> / <jats:italic>Fgf</jats:italic> 3 mutations that are usually found to occur in most mouse mammary tumors as a consequence of MMTV proviral integration. This work led to the isolation of one MMTV- <jats:italic>Wnt</jats:italic> - <jats:italic>1</jats:italic> junction fragment and one MMTV- <jats:italic>int</jats:italic> - <jats:italic>2</jats:italic> / <jats:italic>Fgf</jats:italic> 3 junction fragment from 2 of the 12 tumors. Further analyses showed that both junction fragments contained the RIII/Sa MMTV-2-specific LTR ORF, indicating that this virus was involved in the development of both tumors. Whether RIII/Sa MMTV-1 and/or RIII/Sa MMTV-3 plays any role in mammary tumor development in RIII/Sa mice remains to be established. Overall, the present study demonstrates, to our surprise, that (i) RIII/Sa mice express, unlike other native mouse strains, three strains of MMTVs; and (ii) the virions are completely different from the virus expressed by another subline of RIII mice, the BR6 mice. </jats:p> |
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| Umfang: | 1055-1062 |
| ISSN: |
0022-538X
1098-5514 |
| DOI: | 10.1128/jvi.78.2.1055-1062.2004 |