NEUROINVASIVENESS OF THE TICK-BORNE ENCEPHALITIS VIRUS VARIANTS ADAPTED TO THE IXODID TICKS
In this study we compared the neuroinvasiveness of the variants of the tick-borne encephalitis virus (TBEV) obtained by adaptation to the ticks: to the one of the main vectors of TBEV Ixodes ricinus and to the secondary vector Dermacentor reticulatus. According to our data TBEV reproduction in the main-vector ticks may result in the increase of the virus neuroinvasiveness for white mice, indicating a similar initial selective impact of the tick cells and mammalian CNS cells in spite of the different maximum virus titers in these systems. Adaptation of TBEV to ticks through passages leads to the emergence of variants with the small-plaque phenotype in PEK cells, and to the decrease of the virus neuroinvasiveness. These changes are characteristic of the virus population, adapted to both primary and secondary TBEV vectors.