Genetic Variants of Borrelia garinii, a Widespread Eurasian Pathogen of Ixodic Tick Borreliosis

摘要

As the result of PCR-RFLP analysis of the degree of similarity between the nucleotide sequences analysis of rrfA-rrlB intergenic spacer DNA of 227 primary isolates of Borrelia garinii and 71 isolates/ampli-cons from GenBank database in different regions of Eurasia revealed significant intraspecific heterogeneity among those of Borrelia. It was shown that genospecies B. garinii had within the two genetic subgroups (20047 and NT29) 16 genetic variants, whose geography was likely to be different. Ixodic tick borreliosis (ITB) is the group of etiologically close diseases caused by human pathogen borre-lias of group Borrelia burgdorferi sensu lato. Two species B. garinii and B. afzelii which cover wide areals within the forest zones [7] are epidemiologically important in Russia and neighboring countries. Taiga (I. persulcatus) and forest (I. ricinus) ticks are the main carriers and long-time keepers of borrelias in nature centers of Eurasia and sources of their pathogens for humans. These ticks are sympatric distributed on the considerable part of European territory that creates the nature centers with two species of carriers. Besides this, borrelias have been found in tick I. trianguliceps, which does not bite people, and in the tick I. pav-lovskyi. The last species has a break-up area that consists of two parts (West Siberian and Far East). Ecologically, I. pavlovskyi is very close to I. persulcatus. Almost everywhere these species are sympatric distributed but I. pavlovskyi less aggressive regards humans. Genospecies B. garinii is widely distributed in various forest ecosystems, has wide range of reservoir hosts and carriers, and substantially determines etiology and epidemiology ITB in Eurasia; it is characterized by significant antigen and genetic heterogeneity [12,15].