Differential activation of biologically distinguishable endogenous mouse type C RNA viruses: Interaction with host cell regulatory factors

Mouse cells contain multiple biologically distinguishable endogenous type-C RNA viruses. Sensitive biologic methods have been utilized to study activation of these viruses from clonal mouse cell lines. The regulatory locus, Fv-1, has been shown to influence the expression of one virus. The presence of a second virus, by itself unaffected by Fv-1, permits the first virus to partially overcome the restriction at Fv-1 in nonpermissive cells. These results provide evidence that the interaction between different endogenous viruses plays a role in their expression.