| | Classification of retroviruses | | Genus | Species | Examples |
| | Alpharetrovirus | Birds | Avian leukosis viruses (AVL), Rous sarcoma virus (RSV) | | Betaretrovirus | Mice, primates, and sheep | Mouse mammary tumor virus (MMTV), Mason-Pfizer monkey virus (MPMV), and Jaagsiekte sheep retrovirus (JSRV) | | Gammaretrovirus | Mice, cats, primates, and birds | Murine leukemia virus (MLV), feline leukemia viruses, gibbon ape leukemia virus, reticuloendotheliosis virus, and xenotropic murine retrovirus (xMRV) | | Deltaretrovirus | Cattle and primates | Bovine leukemia virus, human T-lymphotropic virus | | Epsilonretrovirus | Fish | Walleye dermal sarcoma virus | | Lentivirus | Primates, sheep, cats, and horses | Human immunodeficiency virus (HIV), simian immunodeficiency virus (SIV), Maedi/visna virus, feline immunodeficiency virus (FIV), and equine infectious anemia virus | | Spumavirus | Primates, cats, and cattle | Human foamy virus (HFV), simian foamy virus (SFV), feline foamy virus, and bovine foamy virus |
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