Abstract
Incubation of L929 cells with three different glucocorticoids, hydrocortisone, dexamethasone and triamcinolone acetonide, rendered the cells unable to support plaque formation by several unrelated DNA and RNA viruses. The establishment of this antiviral state by dexamethasone coincided with an inhibition of cell growth and induction of glutamine synthetase activity. These steroid-mediated activities occurred only in cultures of L929 cells and not in cultures of rabbit skin or rat glioma cells.