Evaluation of the Analytical Capabilities of MALDI-TOF Mass Spectrometry in the Molecular Typing of <i>Bacillus anthracis</i>

The aim of the work was to compare the discriminating capacity of the canSNP13 genotyping and MALDI‑TOF mass spectrometry methods based on the results of the study of anthrax pathogen strains belonging to the two main genetic lines A and B. Materials and methods. 73 Bacillus anthracis strains from the collection of microorganisms of the Stavropol Research Anti-Plague Institute of the Rospotrebnadzor were investigated. Protein profiling was carried out using a Microflex mass spectrometer, data processing – in the environment of the statistical programming language “R”. Results and discussion. It has been experimentally confirmed that the proposed approach for differentiating proteotypes of B. anthracis strains with a discrimination index of 0.952 exceeds the one for the canSNP typing method and is comparable to the discrimination index for the MLVA31 method. The correlation of the results of strain clustering during typing by MALDI-TOF mass spectrometry and canSNP genotyping reaches 95 % as regards the division into the main genetic lines A and B. The studied strains of anthrax microbe, which mostly fall under phylogenetic groups of lineage A, represent more than a dozen protein profiles, which may be due to differences in the level of protein expression in strains of each canSNP genotype. MALDI-TOF mass spectrometry makes it possible to obtain the results comparable with genetic tests, has a better discriminating capacity compared to canSNP typing, and is easier to perform.