Genetic Heterogeneity of Francisella tularensis Subspecies mediasiatica Strains

The aim of the study was to conduct comparative phylogenetic analysis of Francisella tularensis subsp. mediasiatica strains isolated in different territories of contemporary Republics of Kazakhstan, Uzbekistan, Altai Territory, and the Altai Republic in the period between 1960 and 2024. Materials and methods . We used 77 F. tularensis strains isolated in the territories of Kazakhstan, Uzbekistan, Altai Territory and the Altai Republic of the Russian Federation in the period from 1960 to 2024. To determine the subspecies, the INDEL typing method was used. VNTR genotyping was carried out at 5 loci. Identification of clonal complexes was carried out using the MST method. Results and discussion . Comparative analysis of VNTR genotypes of 42 F. tularensis subsp. mediasiatica strains circulating in natural foci of Altai between 2011 and 2024 made it possible to identify three clonal complexes (CC1-CC3), represented by 13, 14 and 7 individual genotypes, respectively. Strains of the “Kazakhstan” population of F. tularensis subsp. mediasiatica are represented by a separate clonal complex CC4. It has been established for the first time that the “Altai” population of F. tularensis strains of the subspecies mediasiatica is represented by three clonal complexes CC1-CC3. In the same territories of the Altai region, strains of different clonal complexes can circulate at different times. High genetic diversity of the Altai population subsp. mediasiatica was noted (Nei diversity index DI = 0.991). For the first time, a comparable phylogenetic analysis of the “Kazakhstan” and “Altai” populations of the causative agent of tularemia subsp. mediasiatica has been carried out. It is shown that the “Kazakhstan” population forms a separate clonal complex CC4 and it is connected with the Altai clonal complexes through different clones. The results of genotyping indicate the possible origin of the “Altai” population of mediasiatica subspecies.