Thymidine kinase from herpesvirus

Thymidine kinase from herpesvirus is a sub-family of thymidine kinases that catalyses the transfer of phospho group of ATP to thymidine to generate thymidine monophosphate, which serves as a substrate during viral DNA replication. Its presence in herpesvirus-infected cells is used to activate a range of antivirals against herpes infection, and thus specifically target the therapy towards infected cells only.

Source: Wikipedia — Thymidine kinase from herpesvirus (CC BY-SA 4.0)