Isolation and characterization of C-type viral gene products of virus-negative mouse cells.

Antigens which immunologically cross-react with two mouse C-type viral polypeptides, p30 and p12, are present at very low levels in normal virus-negative mouse cells. These two antigens have been purified by 50-300-fold from cell extracts and shown to cochromatograph with the corresponding labeled viral polypeptides in several systems. Their type-specific antigenicities are shown to be distinct from those of previously tested MuLV isolates suggesting that they may be components of a new class of endogenous C-type virus. The methods utilized in the present studies for concentration of virus-specific antigens of normal mouse cells provide an approach for detection of C-type viral antigens in cells of other species.