Antiviral activity of propolis special extract GH 2002 against Varicella zoster virus in vitro .

Propolis is a generic name for a biological substance produced by bees used for multiple purposes in folk medicine. Propolis special extract GH 2002 is crude propolis highly purified by a special procedure and freed from the accompanying substances like pollen, wax, resins. The cytotoxic and antiherpetic effect of propolis extracts against Varicella zoster virus (VZV) was analysed in cell culture, and revealed a moderate cytotoxicity on lung fibroblasts with a CC ₅₀ of 380 μg/ml. The 50 % inhibitory concentration (IC ₅₀ ) of GH 2002 propolis extract for VZV plaque formation was determined at 64 μg/ml. The propolis extract exhibited high levels of antiviral activity against VZV in viral suspension tests, infectivity was significantly reduced by 93.9 % and a direct concentration-dependent antiviral activity could be demonstrated. In order to determine the mode of virus suppression by propolis, the extract was added at different times during the viral infection cycle. Addition of propolis to uninfected cells (pretreatment cells) prior to infection or to infected cells (replication) during intracellular replication had no or only minor effect on virus multiplication. However, propolis exhibited high anti-VZV activity when viruses were pretreated with propolis prior to infection thus indicating an unspecific interaction between the virus and propolis. The antiviral activity is comparable to acyclovir.