Population structure of the B0/W148 Mycobacterium tuberculosis subtype: Phylogenetic analysis and characteristics of genotypic drug resistance

Background. The B0/W148 subtype belongs to the L2phylogenetic lineage of Mycobacterium tuberculosis and is most common in the former Soviet Union. Test systems capable of detecting genetic variants of the pathogen are needed for effective epidemiological surveillance. Studying the genetic diversity of B0/W148 strains and finding molecular markers suitable for their genotyping are key steps in the development of such diagnostic tools. The aim of the work. To study the phylogenetic diversity of the B0/W148 subtype circulating in the territory of the Russian Federation and neighboring countries in order to identify unique clades and search for specific molecular markers suitable for their precise identification. Materials and methods. The study used DNA samples of B0/W148 strains (n = 34) isolated in different regions of the Russian Federation, as well as genomic data obtained from the SRA NCBI (Sequence Read Archive of the National Center for Biotechnology Information) (n = 419). Phylogenetic analysis and principal component analysis (PCA) of whole genome sequencing (WGS) data were used to analyze genetic diversity and to identify molecular markers. An evolutionary reconstruction of the age of the identified clades was carried out. Results. The analysis of the B0/W148 genomes (n = 453) revealed that they are divided into three phylogenetic clades: B – basal, M – minor and P – principal. It was found that specific mutations in the M and P clades allow for their differential diagnosis. The 4137219T>G mutation is unique for the M clade, and the 2241091C>T mutation is unique for the P clade. No characteristic mutations were found among the strains of B clade. In addition, unique mutation profiles in the genes responsible for drug resistance were identified for the clades. Conclusion. The study showed that B0/W148 strains represent a genetically heterogeneous population divided into B, M and P clades. M and P Clades have unique mutations that allow for their identification. It was also found that all clades are characterized by the presence of specific mutation profiles in drug resistance genes.