Tick-borne encephalitis (TBE) is viral zoonosis transmitted by the bite of infected ticks. About 20 years ago, the TBEV was divided into three main subtypes based on the phylogenetic analysis: European, Siberian, and Far-Eastern. The geographic distribution of subtypes mostly corresponds to the nominal region. However, some exceptions are known. Herein, 848 TBEV sequences (1028 nt E-gene fragments) were analyzed to indicate all long-distance virus transfers, that can be revealed from the sequence data. Threshold of 500 km was used for the selection of long-distance virus transfers. Temporal estimates for these events were obtained using Bayesian evolutionary analysis. Noteworthy, ticks are not able to spread the infection on their own over such a distance. In other words, these long-distance virus transmissions were caused by vector-assisted tick transmission. In all subtypes and most of the smaller groups in these subtypes, there were a lot of recent long-distance virus transfers. Moreover, this is suggested to be a systematic pattern, rather than anecdotal events. Most of the known sequences of the European subtype were obtained in Switzerland, n=41 out of 178, or the Czech Republic, n=35 out of 178. Genetic diversity of viruses found within each of these two countries was comparable with the diversity of the whole subtype, n=178. At the same time, this subtype is distributed throughout Central and Eastern Europe, Altai, the Irkutsk Region (Russia), and South Korea. The above arguments allow us to state that long transfers may be considered as a normal and abundant pattern in TBEV spreading.
