Genus Gammaretrovirus
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Type Species |
Murine leukemia virus |
(MLV) |
Distinguishing Features
Virions exhibit a ‘C-type’ morphology with barely visible surface spikes. They have a centrally located, condensed core. Capsid assembly occurs at the inner surface of the membrane at the same time as budding. Protein Mr are: MA ± 15 
103; p12 ± 12 103; CA ± 30 103; NC ± 10 103; PR ± 14 103; RT ± 80 103; IN ± 46 103; SU ± 70 103; TM ± 15 103. The genome is about 8.3 kb in size (one monomer); its organization is illustrated in Figure 4. The pro-pol region is translated following ribosomal readthrough at the gag gene termination codon. There are no known additional genes. The tRNA primer is tRNAPro, (tRNAGlu is found in a few endogenous mouse viruses). The LTR is about 600 nts long of which the U3 region is 500 nts, the R sequence 60 and the U5 region some 75 nts in size.
The viruses are widely distributed; exogenous (vertical and horizontal transmission) and endogenous viruses are found in many mammals. The reticuloendotheliosis viruses comprise a few isolates from birds with no known corresponding endogenous relatives. Related endogenous sequences are found in mammals. The viruses are associated with a variety of diseases including malignancies, immunosuppression, neurological disorders, and others. Many oncogene-containing members of the mammalian and reticuloendotheliosis virus groups have been isolated.
List of Species Demarcation Criteria in the Genus
The list of species demarcation criteria is:
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Differences in genome sequence and viral oncogenes, |
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Differences in antigenic properties, |
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Differences in natural host range, |
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Differences in pathogenicity. |
There are mammalian, reptilian and avian (reticuloendotheliosis) viruses. The mammalian viruses include replication competent viruses that lack cell-derived oncogenes and replication defective viruses that have acquired a variety of oncogenes from their hosts.
Murine leukemia virus (MLV) can be distinguished from Gibbon ape leukemia virus (GALV), for example, by sequence divergence, distinct receptors for virus entry and only limited antigenic cross reactivity in ELISA assays. Murine sarcoma viruses, which are invariably replication defective, can be distinguished from the MLVs and from one another by the presence of distinct cell-derived oncogenes (Moloney murine sarcoma virus (mos) versus Wooley monkey sarcoma virus (sis)) and the characteristic loss of portions of gag, pol or env.
List of Species in the Genus
Official virus species names are in italics. Tentative virus species names, alternative names ( ), strains or serotypes are not italicized. Virus names, genome sequence accession numbers [ ], and assigned abbreviations ( ) are:
Species in the Genus
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Mammalian virus group: |
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Replication competent viruses: |
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Feline leukemia virus |
[M18247] |
(FeLV) |
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Gibbon ape leukemia virus |
[M26927] |
(GALV) |
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Guinea pig type-C oncovirus |
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(GPCOV) |
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Murine leukemia virus |
[J02255] |
(MLV) |
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Abelson murine leukemia virus |
[J02009] |
(AbMLV) |
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AKR (endogenous) murine leukemia virus |
[J01998] |
(AKRMLV) |
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Friend murine leukemia virus |
[M93134, Z11128] |
(FrMLV) |
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Moloney murine leukemia virus |
[J02255] |
(MoMLV) |
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Porcine type-C oncovirus |
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(PCOV) |
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Replication defective viruses: |
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Finkel-Biskis-Jinkins murine sarcoma virus |
[K02712] |
(FBJMSV) |
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Gardner-Arnstein feline sarcoma virus |
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(GAFeSV) |
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Hardy-Zuckerman feline sarcoma virus |
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(HZFeSV) |
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Harvey murine sarcoma virus |
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(HaMSV) |
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Kirsten murine sarcoma virus |
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(KiMSV) |
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Moloney murine sarcoma virus |
[J02266] |
(MoMSV) |
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Snyder-Theilen feline sarcoma virus |
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(STFeSV) |
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Woolly monkey sarcoma virus (Simian sarcoma virus) |
[J02394] |
(WMSV) |
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Reptilian virus group: |
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Viper retrovirus |
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(VRV) |
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Avian (Reticuloendotheliosis) virus group: |
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Chick syncytial virus |
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(CSV) |
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Reticuloendotheliosis virus (strain T, A) |
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(REV) |
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Trager duck spleen necrosis virus |
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(TDSNV) |
Tentative Species in the Genus
None reported.
