Acyclovir can help treat herpes. The herpes's simplex virus thymidine kinase can phosphorylate the drug into its monophosphate. As it is a poor substrate for the thymidine kinase of humans, it is not toxic for non-infected cells. This drug competes with dGTP as a competitive inhibitor. Once is enters the DNA, it can act as a chain terminator.

Christine J. Best has written:

'Effects of thymidine kinase deficiency on sensitivity to mutagenic agents in the human lymphoblastoid cell line Raji'

Denise O'Toole has written:

'Isolation and southern blot characterisation of ethyl methanesulphonate-induced mutants at the aprt locus of wild-type and thymidine kinase deficient friend erythroleukaemia cells'

Thymidine is a nucleoside that consists of one thymine molecule linked to a d-doxyribose sugar molecule. Radioactive thymidine is usually used in DNA labeling.

Thymidine- a nucleoside component of DNA; composed of thymidine and deoxyribose