Inhibition of herpes simplex virus type 1 replication by Adeno-associated virus rep proteins depends on their combined DNA-binding and ATPase/Helicase activities

Abstract

Adeno-associated virus (AAV) has previously been shown to inhibit the replication of its helper virus herpes
simplex virus type 1 (HSV-1), and the inhibitory activity has been attributed to the expression of the AAV Rep
proteins. In the present study, we assessed the Rep activities required for inhibition of HSV-1 replication using
a panel of wild-type and mutant Rep proteins lacking defined domains and activities. We found that the
inhibition of HSV-1 replication required Rep DNA-binding and ATPase/helicase activities but not endonuclease
activity. The Rep activities required for inhibition of HSV-1 replication precisely coincided with the
activities that were responsible for induction of cellular DNA damage and apoptosis, suggesting that these
three processes are closely linked. Notably, the presence of Rep induced the hyperphosphorylation of a DNA
damage marker, replication protein A (RPA), which has been reported not to be normally hyperphosphorylated
during HSV-1 infection and to be sequestered away from HSV-1 replication compartments during infection.
Finally, we demonstrate that the execution of apoptosis is not required for inhibition of HSV-1 replication and
that the hyperphosphorylation of RPA per se is not inhibitory for HSV-1 replication, suggesting that these two
processes are not directly responsible for the inhibition of HSV-1 replication by Rep.