The herpes simplex virus type 2 alkaline DNase activity is essential for replication and growth.

A mutant of herpes simplex virus type 2 (HSV-2), which is temperature-sensitive (ts) for the induction of an alkaline DNase activity, was examined at a number of different temperatures. Induction of DNase activity by this mutant resembled that of wild-type (wt) virus at 31 degrees C but was greatly reduced at 38.5 degrees C and barely detectable at 39.2 degrees C. Virus DNA synthesis showed similar patterns, exhibiting wt levels at 31 degrees C, reduced levels at 38.5 degrees C and very little incorporation at 39.2 degrees C. Similarly, virus growth in cells infected with this mutant was equal to that of wt at 31 degrees C, slightly reduced at 38.5 degrees C but considerably reduced at 39.2 degrees C. Marker rescue of the ts DNase lesion restored wt levels of virus DNase activity, of virus DNA synthesis and of virus growth, thus providing direct evidence that HSV DNase activity is essential for virus replication.