[Anti alpha-herpesvirus drugs].

Therapy for infectious diseases resulting from alpha-herpesvirus infections has been dramatically improved by the development of acyclovir (ACV). ACV is highly specific against herpes simplex virus type 1(HSV-1), herpes simplex virus type 2 (HSV-2) and varicella-zoster virus (VZV) as ACV is specifically phosphorylated by the thymidine kinases (TKs) of these viruses. These viral TKs are important enzymes for viral replication in vivo; therefore, the growth of TK-deficient mutants is impaired. ACV-resistant viruses are rarely isolated from immunocompetent patients but are frequently obtained from immunocompromised patients. Recently, other anti alpha-herpesvirus drugs, such as valacyclovir and famciclovir, have become available for use in Japan, but the need to develop new antiherpetic compounds with different mechanisms of action remains.