INHIBITION BY METABOLIC ANALOGUES OF PLAQUE FORMATION BY HERPES ZOSTER AND HERPES SIMPLEX VIRUSES.

Maximum adsorption of cells infected with herpes zoster virus to monolayers of human embryonic lung cells occurred in 15 to 30 min. An alkaline overlay allowed development of plaques; acid overlay reduced plaque size but not the number of plaques formed. Iododesoxyuridine and cytosine arabinoside, but not methylisatinthiosemicarbazone, inhibited plaque formation by herpes zoster and herpes simplex viruses. Less than 1 µg/ml of either analogue was sufficient to reduce plaque formation by both viruses by more than 90%. A small number of virus particles initiated plaques in the presence of 10 µg/ml of inhibitor and these may represent resistant variants. The method described represents a sensitive and precise utilization of plaque methodology to measure the efficacy of antiviral compounds.