[Interferon-inducing properties of dry birch bark extract and its effect on experimental infection caused by hepatitis C virus].

The interferon-inducing activity of dry birch bark extract containing betulin and its effect on hepatitis C virus (HCV)-induced infection were studied in the cultured cells. All samples of the extract induced increased interferon (IFN) production when it was orally and intraperitoneally administered. The dose-dependence of the production of IFN showed a direct relation of the extract to interferon induction. There is strong evidence for that the extract can decrease the antigenic and infective activity of HCV in both in vitro experiments and HCV-induced infection in mice. The preventive effect of the extract was found in both the HCV-infected cell cultures and the HCV-infected mice.