S-7 inhibition of Herpes simplex virus type 1 infectivity and replication in cultured cells

The effect of ethyl 2-methylthio-4-methyl-5-pyrimidine, carboxylate (S-7) on the infectivity and replication of herpes simplex virus type 1 in Vero cells was studied. S-7, at the highest concentration lacking toxic effect on cells (40 microg/ml), produced, at various inocula, a 40% inhibition of HSV-1 infectivity with respect to the plaque formation detected in control infected cultures. This inhibitory activity was substantiated by studies on progeny production. We cannot conclude that the inhibition of viral cytopathic effect resides in a specific inhibition of viral enzymes, however, the possibility of a more specific antiviral effect cannot be totally ruled out.