Betaretrovirus

**Definition:** A genus of the family RETROVIRIDAE consisting of viruses with either type B or type D morphology. This includes a few exogenous, vertically transmitted and endogenous viruses of mice (type B) and some primate and sheep viruses (type D). MAMMARY TUMOR VIRUS, MOUSE is the type species.

**Tree numbers:** - B04.613.807.124 - B04.820.650.124