MOLECULAR GENETIC CHARACTERISTICS OF TICK-BORNE ENCEPHALITIS VIRUS CIRCULATING IN THE NORTHWEST BLACK SEA COAST

Aim. To study the molecular structure of the envelope (E) protein gene of the tick-borne encephalitis virus strains isolated in the Northwest Black Sea Coast. Materials and methods. Nucleotide sequencing of the envelope (E) protein gene of the tick-borne encephalitis virus strains 150, 70, 120 and 160 Savran, isolated from ticks in Odessa and Kherson regions in 1988-1990, was carried out by chain-termination method (by F. Sanger). Phylogenetic analysis of these sequences was performed by neighbor-joining method. Strains genotype was determined on the basis of phylogenetic analysis and presence of the signature amino acids. Results. Nucleotide sequencing of the envelope (E) protein gene of the tick-borne encephalitis virus strains 150, 70, 120 and 160 Savran was carried out. Based on phylogenetic analysis the circulation of the European (Western) genotype of tick-borne encephalitis virus in the Northwest Black Sea Coast was confirmed. The identity of the envelope (E) protein gene in the tick-borne encephalitis virus strains of the European genotype isolated in the region was shown. The tick-borne encephalitis virus strains studied were the most related to Pan strain and formed with it the phylogenetic group separated from the other tick-borne encephalitis virus strains of the European genotype. The analysis of amino acid sequences of the tick-borne encephalitis virus strains 150, 70, 120 and Savran 160 revealed presence of four marker amino acid replacements – 67 (N), 266 (R), 306 (V) and 407 (R), in domains II and III of the ectodomain and in the transmembrane segment. Conclusions. The molecular structure of the envelope (E) protein gene of the tick-borne encephalitis virus strains isolated in the Northwest Black Sea Coast was determined. Along with the Far Eastern, the circulation of the European (Western) genotype of tick-borne encephalitis virus in the region was revealed