Effect of diethylstilbestrol on replication and transformation by human herpesviruses

Human embryo fibroblasts treated with diethylstilbestrol (DES) gave rise to slightly increased plaque production by cytomegalovirus (CMV): plaques were also slightly larger in treated cells when compared to those in untreated cultures. There was no significant enhancement of plaque production by herpes simplex virus (HSV) types 1 and 2 in the human cells or in primary rabbit kidney cells treated with DES. Growth analyses of HSV and CMV in DES-treated cells failed to reveal enhancement of virus production when compared to untreated cells. The frequency of biochemical transformation of mouse cells deficient in thymidine kinase (TK) to the TK+ phenotype by HSV was markedly enhanced when cells were pretreated with DES. TK+-transformed colonies arising from DES-treated cells were also larger than those derived from untreated cultures. These reveal that DES increases susceptibility of human cell lines to CMV infection and enhances efficiency of biochemical transformation of mouse cells by HSV.