Drug susceptibilities of isolates of varicella-zoster virus in a clinical study of oral brovavir

Susceptibilities to brovavir [1-beta-D-arabinofuranosyl-E-5-(2-bromovinyl)-uracil] and acyclovir of clinical isolates of varicella-zoster virus obtained from 58 patients with herpes zoster, included in a clinical trial of oral brovavir, were tested by a plaque reduction method. All 101 isolates were significantly susceptible to brovavir; 50% effective dose of brovavir for these isolates ranged between 0.6-4.0 ng/ml (average: 1.29 ng/ml). Brovavir was about 3,000 times more potent than acyclovir against these isolates. No marked change in the susceptibility of isolates from these patients during treatment with brovavir was observed.