EFFECT OF 5-IODO-5'-AMINO-2',5'-DIDEOXYURIDINE ON VARICELLA-ZOSTER VIRUS INVITRO

The antiviral effect of the nucleoside analog 5-iodo-5'-amino-2'5'-dideoxyuridine (AIU) was tested with three isolates of varicella zoster virus (VZV). AIU concentrations of 10 to 800 μM (3.5 to 288 μg/ml) reduced the number of plaques produced by VZV-infected cells and cell-free VZV from approximately 30 to 95%. Smaller plaque size was also observed in the presence of AIU. AIU was less effective than arabinofuranosylthymine in reducing VZV-induced plaques since as little as 5 μg of arabinofuranosylthymine per ml completely blocked plaque formation by cell-free VZV. Toxicity assays with human diploid embryo fibroblast cells were also carried out. Drug concentrations as high as 800 μM were not toxic to human diploid embryo fibroblast cells as determined by radiolabeling of cell deoxyribonucleic acid, ribonucleic acid, and protein.