Analysis of Genetic Variability of Yersinia pestis Strains (Medieval Biovar) Isolated in Natural Plague Foci of the Russian Federation and Mongolia

Parallelism in Speciation and Intraspecific Diversification of the Plague Microbe Yersinia pestis

Modern "molecular genetic (MG) phylogenies" of the plague microbe Yersinia pestis, built on models of neutral evolution using statistical methods of phylogenetic analysis, contradict numerous obvious environmental (ECO) patterns and are not consistent with the concept of adaptatiogenesis. The reason for the discrepancy between MG and ECO phylogenies is seen in the underestimation by the MG approach of parallelisms in the processes of speciation and intraspecific diversification of the plague microbe. ECO methods showed the parallel tritope (almost) simultaneous speciation of three primary genovariants (populations, subspecies) Y. pestis 2.ANT3, 3.ANT2, and 4.ANT1 in three geographical populations of the Mongolian marmot (Marmota sibirica), which in the MG approach is mistaken for polytomy ("Big Bang"), caused by unknown natural phenomena on the eve of the first pandemic (Justinian's plague, 6th-8th centuries AD). The discrepancy between the MG and ECO interpretations of the evolution of intraspecifically-derived phylogenetic subbranches 0.PE and 2.MED is also associated with parallel evolutionary processes in independent lines, based on genovariants 2.ANT3, 3.ANT2, and 4.ANT1. The independence of these phylogenetic lines and parallelisms of sub-branches 0.PE and 2.MED associated with them are not taken into account in the MG approach. The prospect of creating a real phylogenetic tree for Y. pestis depends on a creative synthesis of the two approaches-MG and ECO.

Ecological scenario of the plague microbe <i>Yersinia pestis</i> speciation underlying adequate molecular evolutionary model

It is known that the psychrophilic pseudotuberculosis microbe serotype 1 (Y. pseudotuberculosis 0:1b) causing Far East scarlet-like fever (FESLF) an intestinal infection found in a wide range of invertebrates and vertebrates inhabiting cold regions in the Northern and Central Asia as well as Far East is direct ancestor of the plague causative agent Yersinia pestis. However, the mechanism of Y. pestis speciation remains poorly elucidated. Numerous Y. pestis phylogenies created by using molecular genetic (MG) technologies are largely contradictory, being not in line with reliable data obtained by natural science approaches (e.g., ecology, epizootology, biogeography, and paleontology), which disagree with current evolutionary doctrine (synthetic theory of evolution). The MG approach provides no definitive answer to the questions of where, when, how, and under what circumstances the species Y. pestis arose. One of the reasons for such situation might be due to inadequacy of using the molecular evolutionary model for Y. pestis phylogenetics. Knowledge of the life cycles for the ancestral pseudotuberculosis and derivative plague microbes as well as related unique environmental features allows to create a reliable ecological model for the plague microbe evolution to be further used for assessing patterns of molecular variability and building proper molecular model that might be accepted for MG-reconstruction of plague microbe history. According to the ecological model, the species Y. pestis was formed in a tritopic manner (almost) simultaneously from FESLF clones (populations) in the three geographical populations of the Mongolian marmot-tarbagan (Marmota sibirica) and the flea Oropsylla silantiewi parasitizing on it. The inducer of speciation was coupled to the last maximum (Sartan) cooling in Central Asia occurred 2215 thousand years ago. Soil cooling and deep freezing resulted in altered behavior of the marmot flea larvae with emergence of facultative hematophagy, which, in turn, led to a unique traumatic (compared to routine alimentary) infection route of sleeping marmots with FESLF and, as a result, a unique way of Y. pestis speciation. The molecular model should predict a Y. pestis peripatric tritope speciation, existing numerous parallelisms in intraspecific variability associated with tritope speciation, and the quantum principle of speciation in the highly variable heterothermic (heteroimmune) stressful marmot-flea (Marmota sibirica Oropsylla silantiewi) host-vector environment involving stress-induced mutagenesis. Such molecular model of evolution may be useful for improving molecular methodology of phylogenetic constructions for a wide range of parasitic microorganisms.

Natural Mega-Focus of Yersinia pestis Main Subspecies, Antique Biovar, Phylogenetic Line 4.ANT in Gorny Altai

Objective of this study was to investigate the areal of Yersinia pestis strains of antique biovar, main subspecies, phylogenetic line 4.ANT, as well as to establish the borders and spatial structure of mega-focus in the territory of Gorny Altai. Materials and methods. Complex comprehensive analysis of the properties in Yersinia pestis strains of the main subspecies, circulating in Gorny Altai has been conducted. 33 out of them, isolated predominantly in 2012–2017 have been sequenced. Whole genome SNP analysis and search of marker SNPs was performed using Wombac 2.0 software package. Tree diagram was built applying Maximum Likelihood algorithm, using PhyML 3.1 software on the basis of HKY85 model. Results and conclusions. Based on the results of whole genome SNPs analysis of 33 endemic strains and creation of the tree diagram of Y. pestis strains, the presence of natural mega-focus of Y. pestis belonging to the main subspecies, antique biovar, phylogenetic line 4.ANT has been substantiated. Epizootic manifestations on multiple local areas, characterized by persistent autonomous nature of plague manifestations, are registered on an annual basis. Within the boundaries of the areal of Yersinia pestis main subspecies, antique biovar, phylogenetic line 4.ANT, existence of joint natural foci of Yersinia pestis belonging to non-main subspecies ssp. altaica and ulegeica is established. Location of natural foci of the main and non-main subspecies of Yersinia pestis in different altitudinal belts of the Altai Mountains Range on the whole provides for observed multi-host and multi-vector feature of epizootic manifestations. For the first time ever, the data on the areal of the main subspecies of plague microbe are used for setting the boundaries of its natural focus.