MVLST-Analysis of Bacillus anthracis Strains of the Evolutionary Lineage B

Abstract Anthrax is a particularly dangerous infection caused by the spore-forming bacterium Bacillus anthracis, the pathogenicity of which is provided by the plasmids pXO1 and pXO2, carrying the genes for toxin synthesis and capsules. The species B. anthracis is divided into three evolutionary lineages: A, B, and C. The lineage A is represented by many canSNP groups and is distributed throughout the world. The lineage B is divided into three groups: B.Br.CNEVA (Central Europe), B.Br.Kruger (South Africa), and B.Br.001/002 (South Africa, Korea, the United States, and Eurasia, with most of the area being located in Russia). The aim of this study was comparative wgSNP-analysis and multi-virulence locus sequence typing (MVLST) of a representative sample of B. anthracis strains of the evolutionary lineage B. Fifty five strains of B. anthracis lineage B that were isolated on the territory of Russia, the Soviet Union, and other states were studied. Whole genome sequencing was performed on the DNBSEQ-G400 platform for the strains from SRCAMB. Genome assembly, multiple alignment, and phylogenetic analysis were performed in UGENE, MEGA 7.0, and PHYLOViZ 2.0. MVLST-analysis was performed using MVLSTpXO1 and MVLSTpXO2 schemes. Identification of core SNPs and visualization of the phylogenetic tree for wgSNP-analysis was carried out in Snippy v. 4.6.0 and SplitsTree4 v. 4.19.2. MVLST analysis revealed previously described and new sequence types (alleles of individual genes) and genotypes (combinations of alleles). We found genetic markers in the genes of the main pathogenicity factors of B. anthracis, allowing establishment of the phylogenetic position and probable region of origin of the strain. The genetic relationship of the North Eurasian and Siberian strains of the B.Br.001/002 group with the Eastern European cluster of strains of the B.Br.CNEVA group is shown. The description of the phylogeographic structure of the evolutionary lineage B of B. anthracis revealed the genetic relationship of the clusters of strains of the canSNP groups B.Br.001/002 and B.Br.CNEVA and the evolutionary relationship of these groups with the hypothetical ancestral genotype of B. anthracis lineage B, which looks intriguing.