Background & aims: Ganciclovir is a nucleoside analogue active against cytomegalovirus. The compound has also shown in vitro and in vivo activity against duck hepatitis B virus. We investigated the ability of ganciclovir to inhibit another Hepadnaviridae, the woodchuck hepatitis virus, which is the most closely related with hepatitis B virus. We compared two different quantification methods of woodchuck hepatitis virus DNA.
Methods: We treated seven chronic woodchuck hepatitis virus carriers by daily intravenous injections of 5 mg/kg body weight of ganciclovir for seven consecutive days, and followed the animals for 3 weeks post therapy. In addition to traditional X-ray autoradiography, which is a semi-quantitative method, we evaluated woodchuck hepatitis virus DNA levels with storage phosphor technology.
Results: A reduction in serum woodchuck hepatitis virus DNA was observed during treatment in all animals regardless of pre-treatment viraemia levels when using x-ray films and phosphor storage technology. The latter method allowed calculation of mean values of average phosphor imager signals. When comparing the mean values (+/- 95% confidence intervals) before and during therapy, a significant decrease in woodchuck hepatitis virus DNA (80 to 100%) could be shown. After stopping therapy, virus DNA rebounded in all animals.
Conclusions: Our results show that ganciclovir inhibits viral replication in woodchucks chronically infected with woodchuck hepatitis virus. No signs of toxicity were observed. After dot-blot hybridization, storage phosphor imaging was proven superior to X-ray autoradiography for measuring viral DNA. Storage phosphor technology is highly sensitive, quantitative and easy to handle. By comparing mean values and confidence intervals before and during therapy, treatment effects can be distinguished from natural fluctuations.