Inhibitory effects of acyclic nucleoside phosphonates on human hepatitis B virus and duck hepatitis B virus infections in tissue culture

Abstract

The inhibitory effects of the 9-(2-phosphonylmethoxyethyl)adenine-related compounds (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)-adenine, (S)-9-(3-fluoro-2-phosphonylmethoxypropyl)adenine, (R)-9-(2-phosphonylmethoxypropyl)adenine, (R)-9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine, and (S)-1-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine on human hepatitis B virus replication in the human hepatoma cell line HepG2 2.2.15 and duck hepatitis B virus infection in primary duck hepatocytes were investigated. (R)-9-(2-phosphonylmethoxypropyl-2,6-diaminopurine had the lowest 50%o inhibitory concentrations against hepatitis B virus and duck hepatitis B virus, 0.22 and 0.06 ,iM, respectively, i.e., two-to fivefold lower concentrations than required for (R)-9-(2-phosphonylmethoxypropyl)adenine and 9-(2-phosphonylmethoxyethyl)adenine. All compounds were not toxic in vitro at a concentration of 100 ,uM.In chronic hepatitis B virus (HBV) infection the basic therapy is the administration of interferon, although complete disappearance of virus markers is seldom observed. Hepatitis B e antigen seroconversion, reflecting a drastic decline of viral replication, is seen in only 20 to 40% of patients with HBV infections.More potent antiviral drugs are eagerly awaited, and in light of this, the acyclic nucleoside phosphonates described earlier (3, 4) were considered adequate candidates to be further pursued for the treatment of HBV infections.In an earlier study (6) we investigated the acyclic nucleoside phosphonate 9-(2-phosphonylmethoxyethyl)adenine (PMEA) in two hepatoma cell lines and primary duck hepatocytes. The 50% inhibitory concentrations (IC50) for human HBV and duck HBV (DHBV) were found to be 1.2 and 0.2 ,uM as measured in HepG2 2.2.15 cells and primary duck hepatocytes, respectively.Among the acyclic nucleoside phosphonates several other derivatives were found to have high anti-DNA virus activity (herpes group) or antiretrovirus (human immunodeficiency virus [HIV] and Moloney murine sarcoma virus) activity (1). The most effective HIV inhibitors among the acyclic nucleoside phosphonates were evaluated for their anti-HBV activities in the human hepatoma cell line HepG2 2.2.15. Two of the compounds, candidates for application with humans, were also assayed in primary duck hepatocytes infected with DHBV, in anticipation of studies with chronically DHBV-infected ducklings and chronic hepatitis B patients.PMEA, (S)-9-(3-fluoro-2-phosphonylmethoxypropyl)adenine [(S)-FPMPA], (R)-9-(2-phosphonylmethoxypropyl)-2,6-diaminopurine [(R)-PMPDAP], (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)adenine [(S)-HPMPA], (R)-9-(2-phosphonylmethoxypropyl)adenine [(R)-PMPA], and (S)-9-(3-hydroxy-2-phosphonylmethoxypropyl)cytosine were synthesized by

Hepatitis B virus replication in human HepG2 cells mediated by hepatitis B virus recombinant baculovirus

“…Options currently available for studying the molecular mechanisms of HBV replication and the effects of antivirals and cytokines on HBV production within a cell background of human hepatic origin include using stably [32][33][34][35][36][37][38][39] or transiently transfected cell lines. 14,[40][41][42][43][44][45][46][47][48][49] In this study, we report the development of a novel transient mechanism for studying HBV in the well differentiated human hepatoblastoma cell line HepG2.…”

“…The 2.2.15 cell line which was derived from HepG2 cells and constitutively produces HBV has been used to evaluate in vitro inhibition of HBV replication by various nucleosides [32][33][34][35][36][37][38] including lamivudine, penciclovir, 1-O-octadecyl-sn-glycero-3-phospho-acyclovir (ODG-P-ACV), 1-O-octadecyl-sn-glycero-3-phospho-azidothymidine (ODG-P-AZT), BMS-200475, and also by Phyllanthus amarus. 39 Transient transfection of HepG2 cells have been used to understand various aspects of HBV gene expression and replication at the molecular level.…”

In Vitro Antihepadnaviral Activities of Combinations of Penciclovir, Lamivudine, and Adefovir

“…PMEA has broad-spectrum antiviral activity, being active against herpesviruses, retroviruses, and hepadnaviruses (28). The antihepadnaviral activity of PMEA was first observed in human hepatocellular carcinoma cells stably transfected with HBV and in primary duck hepatocytes infected with DHBV (21,22).…”

The clinical potential of the acyclic (and cyclic) nucleoside phosphonates. The magic of the phosphonate bond

“…4) [12]. In vitro (R)-PMPDAP was about 10-fold more potent than (R)-PMPA against HIV, and, likewise, (R)-PMPDAP was shown to be about 10-fold more potent than (R)-PMPA against HBV [33]. Yet, (R)-PMPA (tenofovir) was developed further as an anti-HIV drug, and later as an anti-HBV drug as well.…”