Vaccines Based on the far-eastern and european strains induce the neutralizing antibodies against all known tick-borne encephalitis virus subtypes

Abstract

Serum of children aged 1 to 16 obtained In the course of clinical trials conducted In the Sverdlovsk region In 2011 was used to study the post-vaccination Immunity. Children were immunized twice with vaccines against the tick-borne encephalitis (TBE) Tlck-E-Vak on the basis of the strain Sofjln of the Far-Eastern subtype and FSME-iMMUN Junior based on the Neudorfl strain of the European subtype. According to the plaque reduction neutralization test (PRNT), both vaccines have a high Immunogenicity: After 30 days since two-Time vaccination in the sera of 100% of children Immunized with the vaccine Tick-E-Vak and in the 95% of children immunized with the vaccine FSME-IMMUN Junior antibodies (AT) against strain Sof)ln were identified in protective titers, whereas 24.5% and 21.4% of children, respectively, had antibody titers higher than 1:10000. Selected sera of recipients with titers from 1:25 to 1:1000 were examined in the PRNT In a single experiment using the So^in (Far-Eastern subtype), Absettarov (European subtype) and Vasilchenko (Siberian subtype) strains. The two vaccines Induced AT against the representatives of all three subtypes.