HERPES-SIMPLEX VIRUS TYPE-1 URACIL-DNA GLYCOSYLASE - ISOLATION AND SELECTIVE-INHIBITION BY NOVEL URACIL DERIVATIVES

We have purified Herpes simplex type 1 (HSV1) uracil-DNA glycosylase f rom the nuclei of HSV1-infected HeLa cells harvested 8 h post-infectio n, at which time the induction of the enzyme is a maximum. The enzyme has been shown to be distinct from the host enzyme, isolated from HeLa cells, by its lack of sensitivity to a monoclonal antibody to human u racil-DNA glycosylase. Furthermore, several uracil analogues were synt hesized and screened for their capacity to discriminate between the vi ral and human uracil-DNA glycosylases. Both enzymes were inhibited by 6-(p-alkylanilino)uracils, but the viral enzyme was significantly more sensitive than the HeLa enzyme to most analogues. Substituents provid ing the best inhibitors of HSV1 uracil-DNA glycosylase were found to b e in the order: p-n-butyl < p-n-pentyl = p-n-hexyl < p-n-heptyl < p-n- octyl. The most potent HSV1 enzyme inhibitor, 6-(p-n-octylanilino)urac il (OctAU), with an IC50 of 8 muM, was highly selective for the viral enzyme. Short-term [H-3]thymidine incorporation into the DNA of HeLa c ells in culture was partially inhibited by OctAU, whereas it was uncha nged when 6-(p-n-hexylanilino)uracil was present at concentrations tha t completely inhibited HSV1 uracil-DNA glycosylase activity. These com pounds represent the first class of inhibitors that inhibit HSV1 uraci l-DNA glycosylase at concentrations in the micromolar range. The resul ts suggest their possible use to evaluate the functional role of HSV1 uracil-DNA glycosylase in viral infections and re-activation in nerve cells.