5-(1-Azidovinyl)-2′-deoxyuridine (AzVDU) and a series of 5-[1-azido-2-halogenoethyl]-derivatives of β-d-arabinofuranosyluracil (AU) proved markedly inhibitory to the replication of herpes simplex virus type 1 (HSV-1) and varicella zoster virus (VZV), but not thymidine kinase (TK)-deficient HSV-1 and VZV strains. After corneal inoculation of mice with TK− HSV, the incidence of acute and latent trigeminal ganglion infection was markedly decreased compared to TK+ virus. The ACV-r phenotype was demonstrated to be due to the production of truncated TK polypeptide. Two sets of primer extension fragments were identified, one corresponding to transcription initiation at or near the cap site of the FSH-β gene, the other to transcription initiation within the tk gene. Since overproduction of tk is observed only at late times of infection, it is suggested that the presence of these thymidine analogues in either the viral DNA or the cellular nucleotide pools is responsible for the observed differential effects. Mice infected with theHyTK-expressing parasites and treated with ganciclovir had a statistically significant reduction of parasitemia by 57%; however, complete eradication of parasites was not achieved. The tk protein was also functional in the testes, since spermatogenesis was either arrested or the germinal epithelium almost completely destroyed in transgenic males treated with the antiherpetic agent.
Using an in vitro [3H]-thymidine phosphorylation assay, we demonstrated that the kinase activity of the protein IX-TK fusion protein incorporated into adenoviral virions is functional.