Abstract
Three mutants of herpes simplex virus (HSV) have been isolated which form plaques in the presence of 100 µg/ml phosphonacetic acid (PPA). All three mutants (3 from HSV-1 strain 17 syn+, 14 from HSV-1 strain 17 syn, and 19 from HSV-2) induce viral DNA synthesis and viral DNA polymerase activity, and these are much less sensitive to PPA than the wild-type virus. The results support the hypothesis that PPA interacts directly with the viral DNA polymerase protein, at least part of which is virus coded.