Evaluation of 1-(2'-deoxy-2'-fluoro-beta-D-arabinofuranosyl)-5-ethyluracil in a rabbit model of herpetic keratitis

Inhibition of B virus (Macacine herpesvirus 1) by conventional and experimental antiviral compounds

B virus infection of humans results in high morbidity and mortality in as many as 80% of identified cases. The main objective of this study was to conduct a comparative analysis of conventional and experimental antiviral drug susceptibilities of B virus isolates from multiple macaque species and zoonotically infected humans. We used a plaque reduction assay to establish the effective inhibitory doses of acyclovir, ganciclovir, and vidarabine, as well as those of a group of experimental nucleoside analogs with known anti-herpes simplex virus activity. Four of the experimental drugs tested were 10- to 100-fold more potent inhibitors of B virus replication than conventional antiviral agents. Drug efficacies were similar for multiple B virus isolates tested, with variations within 2-fold of the median effective concentration (EC(50)) for each drug, and each EC(50) was considerably lower than those for B virus thymidine kinase (TK) mutants. We observed no differences in the viral TK amino acid sequence between B virus isolates from rhesus monkeys and those from human zoonoses. Differences in the TK protein sequence between cynomolgus and pigtail macaque B virus isolates did not affect drug sensitivity except in the case of one compound. Taken together, these data suggest that future B virus zoonoses will respond consistently to conventional antiviral treatment. Further, the considerably higher potency of FEAU (2'-fluoro-5-ethyl-Ara-U) than of conventional antiviral drugs argues for its compassionate use in advanced human B virus infections.

Effect of 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-ethyluracil on mitochondrial functions in HepG2 cells

The effects of 1-(2-deoxy-2-fluoro-beta-D-arabinofuranosyl)-5-ethyluracil (D-FEAU) on mitochondrial functions were examined in HepG2 cells. D-FEAU between 0.1 and 10 microM had no apparent inhibitory effect on cell proliferation for 2-week period; however, D-FEAU caused a decrease in mitochondrial DNA (mtDNA) content in a dose-dependent manner with an IC50 value of 2.7 microM. A 20.9% of increase in lactic acid production was observed after the cells were incubated with 10 microM of D-FEAU for 4 days without substantial effect being detected at 0.1 and 1 microM. In addition, no significant changes on mitochondrial morphology were observed in the cells treated with 10 microM of D-FEAU for 14 days under the electron microscope.