Молекулярно-генетический анализ штаммов Yersinia pestis, выделенных в различные эпизоотические периоды на территории Урало-Эмбенского пустынного природного очага чумы в ХХ веке

Abstract

We performed a molecular genetic analysis of Yersinia pestis strains isolated in the Ural-Embensky desert natural plague focus area in the twentieth century. We studied 24 strains of Y. pestis isolated on this territory since 1945 to1991, as well as 21 strains of Y. pestis from adjacent territories. All of the strains studied from the Ural-Embensky natural focus of plague belonged to the highly virulent and epidemically significant medieval biovar of the main subspecies Y. pestis. According to the results of the WG-SNP analysis and subsequent phylogenetic reconstruction based on 1353 SNPs, the maximum likelihood method (Maximum Likelihood, GTR model) revealed 6 key phylopopulations, which included strains isolated during different periods of epidemic and epizootic activity in the study area. It has been established that there were three waves of spread of the 2.MED1 branch of the medieval biovar to the territory of Ural-Embensky desert natural plague focus. Strains isolated before 1945 belong to the first wave of spread of the 2.MED1 branch to the territory of the Northern Caspian Region. The second wave is considered to be the 1968–1974 strains. They have close genetic similarities with strains from the Mangyshlak (1978) and Ustyurt desert plague foci (1962 and 1975). The third wave includes strains isolated after 1966. They are genetically close to the strains from the North Aral foci (1945). The data obtained will be used for molecular-genetic detailing of the certification of foci in which this highly virulent medieval Y. pestis biovar circulates. They are important for determining the patterns of spatiotemporal distribution of highly virulent strains of the 2.MED1 branch of the medieval biovar in the 20th century and for long-term forecasting of the epizootic activity of plague foci in the North-Eastern Caspian region in the current 21st century.