Effects of caffeine on herpes simplex virus.

At concentrations greater than 1 mg/ml, caffeine inhibited plaque formation by herpes simplex virus type 1 (HSV-1), suppressed growth of HSV-1 at various steps of the replicative cycle, but did not inactivate virus infectivity. These effects were independent of each other and persisted through completion of virus replication, as determined by one-step growth studies. Some replication steps appeared to recover after removal of caffeine. Strong inhibition of the spread of HSV by caffeine also was demonstrated by infectious center assay. Caffeine suppressed protein synthesis, in particular that of three viral proteins.