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Genetic Diversity of Siberian Isolates of Borrelia burgdorferi Sensu Lato by the ospA Gene

Year: 2025

Type: article

Abstract: The genetic diversity of the ospA gene of the Borrelia burgdorferi sensu lato species complex encoding outer surface protein A has been widely investigated. However, the information on the genetic variability of Borrelia isolates from Siberia for this gene is limited. In this study, we analyzed complete ospA gene sequences from 36 Borrelia isolates from Western Siberia, comprising 6 Borrelia afzelii, 16 Borrelia bavariensis, 1 Borrelia garinii, and 13 “Candidatus Borrelia sibirica” isolates. The obtained ospA gene sequences of B. afzelii were conserved and formed a single clade. In contrast, B. bavariensis sequences were highly variable, segregating into two distinct clades consistent with the phylogeography of Asian isolates. Notably, the B. bavariensis samples identified in molted Ixodes trianguliceps and Ixodes apronophorus were first characterized for the ospA gene; the obtained sequences corresponded to those from I. persulcatus. This study provides the first characterization of the ospA gene in “Candidatus B. sibirica”, revealing highly conserved sequences (99.8–100% intraspecific identity). The ospA gene sequences of “Candidatus B. sibirica” shared less than 88.7% identity with those of other Borrelia genospecies. Phylogenetic analysis placed “Candidatus B. sibirica” in a unique, well-supported clade, confirming its distinct phylogenetic status and suggesting potential ecological specialization in nidicolous Ixodes species.

Source: Microorganisms

DOI: 10.3390/microorganisms13122825