Dexamethasone enhances human cytomegalovirus replication in human epithelial cell cultures

An epithelial human hepatoma cell line (PLC/PRF/5) and a primary epithelial human baby kidney (HBK) cell culture showed restricted growth of human cytomegalovirus (HCMV). Treatment of these two epithelial cell cultures with dexamethasone greatly enhanced their ability to support HCMV replication. Growth kinetic experiments and infectious center assay revealed that in both the hormone-treated cultures infectious progeny virus appeared earlier by 1 or 2 days and 5- or 10-fold more cells are able to produce infectious virus. There was an approximate 50- or 100-fold increase in virus yield compared to that in the untreated control cultures. Enhanced HCMV replication in the hormone-treated cultures was not due to differences in the cell growth or the virus adsorption and was supported by evidence of increased synthesis of HCMV-specific immediate early antigens and DNA.