A betaretrovirus is a genus of the retroviridae family. It has type B or type C morphology. The type B is common for a few exogenous, vertically transmitted and endogenous viruses of mice, some primate and sheep viruses are the type D. See genus (mathematics) for the use of the term in mathematics. ... Genera Alpharetrovirus Betaretrovirus Gammaretrovirus Deltaretrovirus Epsilonretrovirus Lentivirus Spumavirus A retrovirus is a virus which has a genome consisting of two identical plus sense RNA molecules. ... Scientific classification or biological classification refers to how biologists group and categorize extinct and living species of organisms. ... Morphology is the following: In linguistics, morphology is the study of the structure of word forms. ... Feral mouse Feral mouse A mouse is a mammal that belongs to one of numerous species of small rodents in the genus Mus and various related genera of the family Muridæ (Old World Mice). ... Families 13, See classification A primate is any member of the biological order Primates (Latin primus first), the group that contains all lemurs, monkeys, apes, and humans. ... Binomial name Ovis aries Linnaeus, 1758 A sheep is any of several woolly ruminant quadrupeds, but most commonly the Domestic Sheep (Ovis aries), which probably descends from the wild moufflon of south-central and south-west Asia. ...

An example is the mouse mammary tumour virus.