Molecular typing of the tick-borne encephalitis virus isolated from patients with different-infection severities in the south of Russia's Far East

The thick-borne encephalitis virus (TBEV), which is widespread in the Eurasian continent, belongs to the Flaviviridae family, Flavirus genus, and comprises the Far Eastern, Siberian and West European subtypes. It was for the first time that the gene part of the E 24 strain envelope glycoprotein of TBEV, which caused infection in residents of the South of Russia's Far East, was analyzed. It was established that the TBEV Far-Eastern subtype causes different-severity disease cases ranging from the focal ones with the lethal outcome to latent infection forms. On the basis of the phylogenetic analysis, the Far-Eastern subtype was shared between 4 sub-clusters, 2 of which constitute a majority of the analyzed TBEV strains.