thymidine kinase

[Michael Ostrander]

To correct a common misunderstanding, ACV does NOT inhibit the HSV 
thymidine kinase (TK). ACV is an alternative substrate for the enzyme and 
undergoes preferential phosphorylation by viral TK but not by cellular TK.
  The resulting ACV monophosphate is then phosphorylated to the 
triphosphate. The ACV triphosphate is itself an alternative substrate for 
DNA polymerases resulting in incorporation into viral DNA and termination 
of DNA elongation.

Mike