Detection of human cytomegalovirus early and late antigen and DNA production in cell culture and the effects of dimethyl sulfoxide, dexamethasone, and DNA inhibitors on early antigen induction.

Recently a conventional method for the laboratory diagnosis of human cytomegalovirus (HCMV) infection was improved by using centrifugation culture to enhance viral adsorption and by detecting HCMV early antigen and DNA. Comparison of the sensitivity of three rapid methods using commercial diagnostic reagents for the detection of HCMV early antigen (EA), late antigen (LA), and DNA was quantitatively evaluated in centrifugation cultures of human fibroblast cells (MRC-5) infected with HCMV. HCMV-EA was first detected 4 hours after infection, and the number of antigen-positive cells increased rapidly thereafter. Using biotinylated DNA probe, viral DNA was first detected 12 hours postinfection; the number of DNA-positive cells increased slowly. HCMV-LA was first seen 48 hours postinfection, and the number of LA-positive cells also increased thereafter. Thus detection of HCMV-EA was the most rapid and sensitive method for HCMV diagnosis. Several chemical compounds have been used to enhance HCMV replication. The effect of dimethyl sulfoxide (DMSO), dexamethasone (DEX), 5-bromo-2-deoxyuridine (BrdU), 5-fluoro-deoxyuridine (FdU), and cytosine arabinoside (Ara-C) on HCMV-EA induction was evaluated in centrifugation cultures of MRC-5 cells infected with HCMV. Infected cells treated with 1% DMSO alone or with DMSO plus DEX (10(-5) M) have been shown to increase the number of HCMV-EA-positive cells three- to fivefold over the untreated control cultures. The enhancing effects of Ara-C, BrdU, and BrdU plus FdU were demonstrated only occasionally.