Acyclovir is an antiviral drug used to treat herpesvirus infections. It works by interfering with the synthesis of the virus DNA. In humans, acyclovir is used to treat the varicella zoster virus (chickenpox) and herpes zoster virus (shingles).
Since Marek's disease
virus is also a herpesvirus, acyclovir has been studied for it's use in the treatment of Marek's Disease in chickens. In studies, the use of acyclovir inhibited in vitro replication of turkey herpesvirus and Marek’s disease virus in chick embryos. It was also shown to diminish the development of tumours in birds infected with Marek’s disease virus in adult chickens.