Yar-viruses belong to the ''Baltic'' group of the Siberian TBEV subtype Phylogenetic analyses based on a 1110-bp fragment of the E gene (positions 1114-2224 in Vs virus L40361) showed that the Yar-viruses belong to the SIB subtype of TBEV [9, [22] [23] [24] [25] [26] , which includes the control Vs virus (see Methods). Fig. 1 illustrates the overall branching pattern in agreement with previously published results [24, 25] . Three Siberian sub-clusters I, II and III were clearly identifiable and supported by high bootstrap values. Yarviruses were grouped with strains of sub-cluster III designated ''Baltic'' [27] , isolated only in Europe, in contrast to strains of clusters I and II that were found across Europe and Asia. Separate phylogenetic analyses based on the C, prM, E and NS1 genes produced trees that were congruent with the one presented (data not shown).