In the Central Asia desert natural focus of plague, the major carrier of the Yersinia pestis agent is the great gerbil Rhombomys opimus, and its vectors include fleas of the Xenopsylla genus. Phenotypical and genotypical properties of the R. opimus populations, Xenopsylla fleas and Yersinia pestis strains have been studied in the Central Asia desert natural focus of plague. Phenotypic distinctions and population discreteness have been identified in R. opimus on the cytochrome b gene of the mitochondrial genome from three autonomous plague foci: Pre-Balkhash, Betpakdala and Pre-Ustyurt. Phenotypic distinctions have been found in Xenopsylla fleas in the Central Asia desert natural focus of plague, and the genotype of X. gerbilli minax fleas on the Cox2 gene of the mitochondrial DNA; these had been captured in the Betpakdala autonomous focus. The repertoire diversity in phenotypical properties of Y. pestis strains from different natural foci of plague has been demonstrated, and population discreteness of Y. pestis strains has been determined using the next-generation sequencing method for single nucleotide polymorphism genes. Results of the study suggest that geographical and environmental isolation and natural selection have led to heterogeneity in the three populations of the great gerbil, vector fleas and Y. pestis.

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