Deoxyribopyrimidine triphosphatase activity specific for cells infected with herpes simplex virus type 1

Nuclei from baby hamster kidney cells infected with herpes simplex virus type 1 contain a virus-specific deoxyribonucleoside triphosphate degrading activity. The reaction proceeds at 4 degrees C and can thus be distinguished from host enzymes. Under these conditions the enzyme is specific for deoxyribopyrimide triphosphates and catalyzes pyrophosphate cleavage to produce the monophosphates, dUTP being the best substrate followed by dCTP and dTTP. The appearance of the activity after infection parallels that of viral DNA-synthesis-related functions. Of a series of eight temperature-sensitive mutants tested, two (tsD and tsK) exhibit significantly decreased triphosphatase levels after infection at nonpermissive temperature, whereas a viral deoxypyrimidine kinase-deficient mutant induced wild-type levels.