Abstract
BHK 21 cells infected with high multiplicities of polyoma virus show transiently various characteristics of transformed cells, including the appearance of the polyoma specific surface antigen (S antigen), as detected by immunofluorescence. Various inhibitors were tested for their effect on S antigen. Drugs interfering with DNA synthesis were found to block the appearance of this antigen, but did not affect its disappearance. On the other hand, actinomycin D did not block S antigen formation, but blocked its disappearance, and appeared to favour the maintenance of the BHK21 cell in the abortively transformed state. Inhibitors of protein synthesis prevented the appearance of S antigen. These results are discussed in relation to other results on the effect of inhibitors on virus-induced antigens or on virus-induced unmasking of some lectin sites.