The role of herpes simplex virus type 1 thymidine kinase in pathogenesis

A genetically engineered herpes simplex virus type 1 (HSV-1)thymidine kinase (TK) deletion mutant has been constructed and used to investigate the role of this gene in pathogenesis. Inoculation of mice with the HSV TK deletion mutant resulted in the establishment of latent ganglionic infection as demonstrated by superinfection of explanted ganglia with wild-type (wt) virus but not by routine explant culture suggesting that the virus-encoded TK is not essential for the establishment of latent infection but may be necessary for either reactivation or virus replication following reactivation. In addition, Southern blot hybridization has been used to demonstrate in vivo complementation of this mutant by wt virus in both peripheral and central nervous system tissues of mice during acute infection and to show that such complementation can result in the establishment and reactivation of latent TK- infection.