Evaluation of European tick-borne encephalitis virus vaccine against recent Siberian and far-eastern subtype strains

To evaluate the efficacy of the European TBE, vaccine in east-Siberian and far-eastern. regions of Russia, we examined the immune responses of the vac cine against recent TBE virus Siberian (Irkutsk) and far-eastern (Khabarovs k and Vladivostok) isolates. The sera of vaccinated humans showed efficient neutralizing antibody titers (greater than or equal to 20) against Siberia n and far-eastern strains. To evaluate the efficacy of the vaccine in vivo, mice were vaccinated and challenged with lethal doses of the viruses. All vaccinated mice survived each virus challenge. These-results suggest that t he European vaccine can prevent the TBE virus infection in east-Siberian an d far-eastern regions of Russia. (C) 2001 Elsevier Science Ltd. All rights reserved.