Proteomic profiling of Yersinia pestis strains circulating in the area of natural plague foci of North Caucasus and Transcaucasia

Aim. To create a database of mass spectra of Yersinia pestis strains, which will differentiate the strains of the main and Caucasian subspecies of the plague agent by MALDI-TOF MS. Materials and methods. MALDITOF mass spectrometry was used to study 50 strains of Y. pestis, isolated on the territory of 7 natural plague foci of the Caucasus and Transcaucasia in the period 1950-2012. The removal of mass spectra of extracts of cells of Y. pestis was performed using the mass spectrometer Microflex LT «Bruker Daltonics». The results were processed and analyzed in FlexAnalysis programs, аnd MALDI Biotyper V. 3.0. Results. Тhis study showed that mass spectra have characteristic features that allow differentiating strains of the main (Y. pestis pestis) and subspecies (Y. pestis caucasica). Peaks characteristic of each subspecies were detected. The presence in Y. pestis caucasica subspecies peaks characteristic of the ancestral form — Y. pseudotuberculosis indicates the ancient origin of this group, which is consistent with the data of molecular genetic and WGS analysis given in other publications. Conclusion. Тhis work shows the possibility of applying the MALDI-TOF method of mass spectrometry for rapid differentiation of strains of the main subspecies Y. pestis pestis from the subspecies Y. pestis caucasica, which have different significance in the development and maintenance of the epizootic process in natural plague foci as well as different virulence for humans. Identification of the strain to the subspecies level requires carrying out culture and biochemical tests, which can take several days. The proposed method makes it possible to differentiate and obtain a result within half an hour after receiving a pure culture.