Endogenous mouse type-C RNA virus of SWR cells: Inducibility locus containing structural information for a new endogenous virus class

A type-C RNA virus with a host range preference for BALB/c mouse embryo cells is chemically inducible from embryo cells of the inbred SWR strain. The SWR virus is shown to be readily distinguishable from previously identified endogenous viruses of mouse cells by nucleotide sequence homology analysis. A single dominant gene for SWR virus inducibility is shown to segregate in crosses involving the inducible SWR and non-virus-inducible NIH Swiss strains. Moreover, nucleotide sequences specific for the SWR virus are demonstrated to be present only in cellular DNAs of SWR virus-inducible embryo lines. These findings establish that the SWR inducibility locus contains structural information of this virus.