Prevalence of sensu lato and in ixodid ticks in the Far East of Russia.

sensu lato (s.l.) DNA was detected by PCR in Schulze, 1930, Koch, 1844 Nuttall et Warburton, 1915 and Olenev, 1932 ticks collected in the Amur region, the Jewish Autonomous region, the Sakhalin region and on the Khabarovsk territory. Infection rate of with s.l. 10-69% exceeded the corresponding values of three other tick species in all examined regions during 1999-2014 despite different tick abundance and dominance structure. Bacterial loads estimated on the base of quantitative real time PCR varied from 10 to 10 genome-equivalents per a tick with maximal values for and Phylogenetic analysis of 16S rRNA gene and 5S-23S rRNA intergenic spacer nucleotide sequences revealed two species: 1) of Asian type NT29 with several isolates of European type 20047; 2) with identical sequences of the majority of studied isolates and VS461 reference strain in all regions except the Sakhalin Island where was not found of the relapsing fever group was detected as monoinfection or in combination with s.l. in 4.0 ± 0.9% and 4.8 ± 0.9% ticks, respectively. Multiple locus sequence analysis of three fragments of 16S rRNA, glpQ and p66 genes proved that all the Far Eastern isolates belonged to the Asian type identical to FR64b strain (GenBank CP004217) from Japan. Wide distribution of DNA in ticks, relative genetic homogeneity with similar sequences of the coding regions and the intergenic spacer of wild isolates and temporal stability with high homology levels of the Far Eastern isolates of , and with previously described spirochetes from the surrounding regions of Russia, China and Japan allowed us to suggest multiple ecological niches as the stability factor of the parasitic system.