An active metabolite of adefovir dipivoxil formed from adefovir dipivoxil by CES2 inhibits cytopathogenicity induced by HSV-1 and HSV-2 (EC50 7 Ug/ml for both in E6SM cells) HIV-1 and HIV-2 (EC50s 1 8 and 2 5 Ug/ml respectively in CEM cells) and VZV (EC50 10 Ug/ml in human embryonic lung fibroblasts) reduces increases in lymph node viral DNA and serum IgG levels in a mouse model of AIDS induced by infection with LP-BM5 at 50 mg/kg inhibits tumor growth induced by MSV infection in mice at 50 mg/kg