Evolution and Geographical Distribution of Brucella melitensis Genetic Line II in the Territory of the Russian Federation

The aim of the work was to conduct phylogeographic and evolutionary analysis of Brucella melitensis strains of genetic lineage II, isolated in the territory of the Russian Federation in the context of studying the global population of the species. Materials and methods . The study used 282 strains of B. melitensis from the collection of pathogenic microorganisms at the Stavropol Anti-Plague Institute of the Rospotrebnadzor. Whole-genome sequencing was performed using the DNBSEQ G50RS sequencer (MGI, China) and the MGIEasy FAST FS DNA Library Prep Set V2.1 kit (MGI, China) according to the standard protocol. Evolutionary and phylogeographic analysis was carried out applying the BEAST v2.7.5 software package. Results and discussion . It has been established that the B. melitensis strains in the Russian Federation belong to four sub-genotypes of the genetic line II, which presumably diverged in the 16th century: IIb, IIg, IIh, and IIi. The singular cases of sub-genotypes IIb and IIg detection in Russia indicate the importation of infection from the Middle East. Sub-genotype IIh is prevalent in Siberia, Mongolia, China, and Kazakhstan. Variants of the most representative and genetically heterogeneous sub-genotype IIi circulate in a vast area from the North Caucasus to Northern China and are usually identified during epidemiological investigations of brucellosis outbreaks in the European part of the country. The results indicate the prospect of using genome-wide SNP analysis as an effective tool for timely detection of non-endemic or atypical variants of the causative agent of brucellosis during genomic profiling of individual regions.