Virus-like particles in cultured C3H/St mouse cells treated with a carcinogenic polycyclic hydrocarbon

Virus-like particles with cylindrical form were found in cultured alveolar macrophages and lung fibroblasts of C3H/St mice, after treating these cells with a carcinogenic polycyclic hydrocarbon, 1, 2, 5, 6,-Dibenzanthracene (DBA). Their morphology looked identical to those observed in vivo in the reactive cells which engulfed DBA crystals implanted into the brain and muscle of the same mouse strain. These particles were not found in either the untreated cells of C3 H/St mice or the treated cells of BALB/c mice. In the alveolar macrophages, these particles appeared first at 3 days after DBA treatment and reached the maximum number around the 30th day. They still kept their morphology in the degenerating cells which had lost the cytoplasmic organelles. These findings suggest the possibility that DBA induced the expression of the viral genome endogeneous to C3H/St cell.