Penciclovir inhibited the productive replication cycle of Epstein-Barr
virus (EBV) in assays measuring infectious virus production, viral an
tigen expression, and viral DNA synthesis. In the test measuring inhib
ition of EBV DNA synthesis, 50% effective concentrations of penciclovi
r and acyclovir were 2.3 +/- 0.8 and 2.2 +/- 0.6 mu g/ml, respectively
. The 50% cell growth inhibitory concentration of penciclovir was >100
mu g/ml for both P(3)HR-1 and Raji cells. Penciclovir is a selective
inhibitor of EBV in cell culture.