Inhibitory effects of foscarnet on herpesvirus multiplication in cell culture.

The effect of phosphonoformate (INN; foscarnet sodium) on Herpes Simplex Virus type 1 replication in cell-culture has been studied. At 55 microM, foscarnet reduced the yield by 50 per cent which correlated well with a 50 per cent reduction of plaque formation at 60 microM. Foscarnet had to be added before 8 hours post infection to inhibit virus production. The inhibition of herpesvirus plaque formation by the presence of foscarnet for 24 hours was not reversed by the removal of the drug. The inhibition of virus replication by foscarnet could, in contrast to the inhibition by acycloguanosine, not be reversed by addition of deoxynucleosides.