Study of a human heteroploid cell line cryptically infected by a murine oncornavirus

This report concerns the establishment of a human cell line cryptically infected by a murine leukemia virus (MuLV). This cell line, named J112, is characterized by the presence of genetic viral information in a majority of cells as demonstrated by immunological and virological methods, and by the absence of detectable viral activity in the supernatant culture fluids. Nevertheless, electron microscopy demonstrated the presence of a small number of particles which have the morphology of immature type C particles. We discuss the importance of this experimental model in relationship with non-producing (NP) infections of human cells by oncogenic retroviruses.