SKV-transformed nonproducer clones were isolated from infected quail and chicken embryo cells. Analysis of intracellular viral RNAs by the Northern technique revealed that each clone contained a single SKV genome (either 5.7 or 8.9 kb) but no genome of the helper virus. Analysis of intracellular viral proteins containing gag determinants revealed that each clone contained a single species of either 55, 110, or 125 kDa. The intracellular location of these proteins was determined by indirect immunofluorescence employing either monoclonal antibodies (anti-p19gag) or conventional antiserum against gag proteins. All three of the SKV-specific proteins were localized to the nuclei of the transformed cells.