Inhibitory effects of 2'-fluorinated arabinosyl-pyrimidine nucleosides on woodchuck hepatitis virus replication in chronically infected woodchucks

Abstract

The treatment of woodchuck hepatitis virus infections with 1-(2'-deoxy-2'-fluoro-4-D-arabinofuranosyl)-5-iodocytosine (FIAC) and 1-(2'-deoxy-2'-fluoro-4-D-arabinofuranosyl)-5-methyluracil (FMAU), given intraperitoneally, caused complete and permanent decrease of serum virus endogenous DNA polymerase and viral DNA in all treated woodchucks but was associated with severe toxicity. By contrast 1-(2'-deoxy-2'-fluoro-l-D-arabinofuranosyl)-5-ethyluracil (FEAU) induced a sustained, although less dramatic, decrease of viral replication without apparent toxic effect. FEAU was also effective when given orally. However, in both cases this inhibitory effect was transient. (7) is often associated with chronic hepatitis leading to liver cirrhosis and hepatocellular carcinoma. So far none of the current treatments, including vidarabine (11, 15), acyclovir (16), alpha interferon (3), and immunomodulatory compounds (18), have been able to satisfy the clinical needs. The discovery of HBV-related animal viruses designated hepadnavirus (8) in woodchucks, ground squirrels, and Pekin ducks offers new possibilities to test potential anti-HBV agents (10,(12)(13)(14). Among the three animal hepadnaviruses, the woodchuck hepatitis virus (WHV) is the most closely related to HBV (6). The natural courses of WHV and HBV chronic hepatitis are comparable, especially progression to hepatocellular carcinoma (5). Thus we investigated in vivo in the woodchuck model the antiviral activity of three compounds of the family of 2'-fluoro-substituted arabinosyl pyrimidine analogs (4) Hepatitis B virus (HBV) infection, and 1-(2'-deoxy-2'-fluoro-i-D-arabinofuranosyl)-5-ethyluracil (FEAU). Indeed, the triphosphate derivatives of these compounds, known as antiherpetic agents, specifically inhibit the viral DNA polymerases of HBV and WHV in vitro (9). FIAC, FMAU, and FEAU were synthesized in the laboratory of organic chemistry of the Memorial Sloan-Kettering Cancer Center. Adenine arabinoside monophosphate (araAMP) was supplied by the Warner Lambert Co. Woodchucks chronically infected with WHV were obtained from our breeding colony initially established from animals imported from Pennsylvania. WHV replication was followed by the detection of WHV DNA polymerase activity in serum by using virus pelleted by ultracentrifugation through a sucrose cushion and by the detection of WHV DNA in serum by the hybridization spot test of Cova et al. (2). The relative amount of WHV DNA in serum was estimated as previously described (2). Forty-six WHV chronic carrier woodchucks were involved in two independent experiments. These animals were divided into two groups: one group of high replicators with WHV endogenous DNA polymerase * Corresponding author. activity higher than 1,000 cpm and the other group including moderate and low replicators (500 to 1,000 and <500 cpm, respectively). Generally, high replicators were younger (age range, 1 to 2 years); conversely, moderate and especially low replicators were older (3 to 4 years of age). In many cases, we observed that lower le...

Antiviral activity and toxicity of fialuridine in the woodchuck model of hepatitis B virus infection

“…Because toxicity of FIAU in woodchucks was not influenced by WHV infection, it was concluded that species-specific differences in the toxicity of FIAU exist between mice, rats, and dogs on one hand and humans and woodchucks on the other. FIAC, 51 a prodrug of FIAU, and the closely related 5-methyl 51 and 5-ethyl 52 analogs all have been reported to have delayed toxicity in woodchucks similar to that observed with FIAU in this study. The similarity of the syndromes of FIAU toxicity in woodchucks and humans suggests that the woodchuck could be a valuable animal model for the recommended 8 further investigation of the pathogenesis of FIAU toxicity and for the preclinical toxicological assessment of related nucleoside analogs undergoing development as potential human drugs.…”

Cellular and molecular events leading to mitochondrial toxicity of 1-(2-deoxy-2-fluoro-1-beta-D-arabinofuranosyl)-5-iodouracil in human liver cells.

“…In 1990, a halogenated nucleoside analogue FIAU was found to have a potent in vivo activity against HBV infection in a chronically infected woodchuck animal model (3). Initial clinical studies of FIAU conducted in HIV infected persons with HBV co-infection for periods of 2 wk supported the animal data with a marked suppression of circulating HBV DNA (4).…”

“…In contrast, 3TC-treated cells did not induce any apparent morphological changes under the same conditions (data not shown). of herpes simplex virus and cytomegalovirus infections (18,29) was recently reported to be also effective against HBV replication (3,4). The anti-HBV activity of the 5 '-triphosphate form of FIAU is assumed to result from its selective inhibition of viral targets, possibly HBV DNA polymerase (30).…”

Mitochondrial DNA Depletion, Oxidative Stress, and Mutation: Mechanisms 0f Dysfunction from Nucleoside Reverse Transcriptase Inhibitors

“…This suggests that the NRTI monophosphate is incorporated into mtDNA. (Fourel et al, 1990), and many of their triphosphates inhibit mammalian DNA pol-␥ in vitro (Lewis et al, 1994a). With these agents, competition with the native nucleotide and NRTI at the nucleotide binding site of DNA pol-␥ appears to be a critical event.…”