Genetic variability of Yersinia pestis in natural foci of the Caspian Region of Kazakhstan (1967–2021)

This study presents a comprehensive analysis of epizootological and epidemiological monitoring of natu- ral plague foci in the Caspian region of the Republic of Kazakhstan. The spatio-temporal characteristics of the Volga-Ural, Ural-Emba, Pre-Ustyurt, and Manghystau plague foci are examined, including their biocenotic specificity, the composition of primary and secondary hosts, and the spectrum of pathogen vectors. The study included 28 Yersinia pestis isolates collected between 1967 and 2021 and preserved in the National Collection of microorganisms of the NSCEDI. Their phenotypic properties, phage susceptibility, molecular-genetic identifi- cation, and comparative analysis by MLVA-25, SNP-typing, and whole-genome sequencing were assessed. The results demonstrated that most strains belong to the Medievalis biovar while unique genetic features were identi- fied, including the presence of the pCKF plasmid in eight isolates from all four foci of the region. Obtained data confirm the persistence of plague epizootic activity in the region and reveal its genetic variability, underscoring the need for regular monitoring and using modern molecular epidemiology methods.