Abstract
Human diploid fibroblast cultures induced to make interferon by the combination of polyriboinosinic acid-polyribocytidylic acid, cycloheximide and actinomycin D degenerate thereafter, owing to the irreversible nature of the inhibition induced by actinomycin D. However, cultures superinduced with the DNA-dependent RNA synthesis inhibitor 5,6-dichloro-1--D-ribofuranosylbenzimidazole (DRB) survive, owing to the reversible nature of the inhibition induced by DRB, and can again be superinduced on several occasions.