Enhanced detection of cytomegalovirus in shell vial culture following MRC-5 monolayer pretreatment with glucocorticoids.

The effect of cortisol and its synthetic derivative, dexamethasone on the infectivity of cytomegalovirus (CMV) was investigated. Twenty-four to 48 h pretreatment of MCR-5 shell vials by 100 micrograms % (compared with medium supplemented with 10 or 25 micrograms %) cortisol affected the greatest increase in virus infectivity (measured in fluorescent focus units/0.2 ml inoculum). This enhancement effect was more pronounced in the CMV strain AD-169 than in a clinical CMV isolate (NCMC 7125). Attempts to reisolate CMV from 32 frozen positive original specimens in the presence or absence of cortisol demonstrated an enhanced infectivity of 8 specimens in hormone pretreated cultures compared with two specimens showing an increased activity in untreated controls. Three specimens were reisolated only in hormone pretreated shell vials. Pretreatment of shell vials maintained in maintenance medium plus 2% FBS with cortisol or dexamethasone (10(-5) M) increased CMV infectivity to ca. 300%. This hormonal mediated effect was more pronounced in 4 rather than 16 day old shell vials. Infectivity in 16 day old shell vials maintained in 10% FBS but without hormone equalled the infectivity levels achieved in 4 day old shell vials with cortisol and either a 2 or 10% FBS supplement. This study denotes the applicability of glucocorticoid pretreatment of MRC-5 monolayers but more importantly, identifies the association between FBS concentration and glucocorticoid-mediated CMV detection using shell vial technology.