Effect of treatment of shell vial cell cultures with dimethyl sulfoxide and dexamethasone and age of MRC-5 monolayers for detection of cytomegalovirus.

Pretreatment of MRC-5 cell monolayers in commercially prepared shell vials with 1% dimethyl sulfoxide (DMSO) and 10(-5) mol/L dexamethasone (DEX) was evaluated. Preliminary experiments indicated enhanced infectivity of AD-169 for pretreated MRC-5 cells in shell vials of ages 9 and 16 days. Compared with untreated shell vials, DMSO-DEX increased positivity (day 9, 19 vs. 26 shell vials, p less than 0.03; day 16, 13 vs. 29 shell vials, p less than 0.001) and increased the mean number of fluorescent foci (days 9 and 16, p less than 0.001). Pretreatment of 8-15-day-old monolayers was evaluated clinically using 146 urine specimens. Fifty specimens were positive for cytomegalovirus (CMV) in both treated and untreated shell vials with ten positive in untreated only and three positive in treated only (p = NS). The median number of fluorescent foci was not significantly higher in treated shell vials. Increased toxicity of MRC-5 cells was observed in treated monolayers (p less than 0.0001). Pretreatment with DMSO-DEX did not enhance CMV isolation from clinical specimens and can be toxic to MRC-5 monolayers.