Comparative Molecular-Genetic Analysis of <i>Francisella tularensis</i> Strains Isolated in the Rostov Region in 2020 and Genome Sequences of the Strains Collected in Various Regions of the World

Six cultures of tularemia microbe from fallen and captured live animals were isolated during epizootiological monitoring in the steppe focus in the south-east of the Rostov Region in 2020 against the background of extensive epizootics in the populations of the common vole Microtus arvalis obscurus and the public vole Microtus socialis.The aim of the work was to develop an SNP-typing scheme and to conduct a comparative study of the phylogenetic relations between Francisella tularensis strains isolated in the Rostov Region (2020) and strains from other regions.Materials and methods. Genome-wide sequencing was performed on the MiSeq Illumina platform. The author’s software GeneExpert, PrimerM and VirtualPCR, written in the Java programming language, were used for the analysis.Results and discussion. The strains of tularemia agent, isolated on the territory of the Rostov Region in 2020, can be allocated to two different clusters. It is established that two strains of tularemia pathogen (F0884 and F0889) isolated in Turkey are genetically close to some isolates circulating in the Rostov Region. A unique INDEL marker characteristic of this group of strains has been identified. The comparison of our proposed typing scheme with the scheme of “canonical” SNPs has showed a fairly good consistency and convergence of results within large clusters, meanwhile using a set of 6626 SNPs allows for differentiating the strains within one canSNP type. It is revealed that the vaccine strain has a common canSNP type with clinical and natural strains. A set of SNP markers has been selected for comparative analysis. A new INDEL marker that enables intraspecific typing of F. tularensis has been discovered and the possibility of its application in vitro and in silico has been comfirmed

Assessment of the Variation Range of Agglutinability in <i>Vibrio cholerae</i> Strains Isolated in the Course of Monitoring Studies

The aim of the study was to retrospectively analyze the range of variability of antigenic properties and genotypic characteristics of Vibrio cholerae R-variant strains atypical in terms of agglutinability.Materials and methods. 169 strains of V. cholerae R-variant with atypical agglutinability have been studied using the “AmpliSens® Vibrio cholerae-FL” test-system. The determination of O1 antigen was carried out using the “Ig-V. cholerae О1/О139 – ELISA/dot-ELISA” reagent kit.Results and discussion. A retrospective analysis of the complex of phenoand genotypic characteristics of strains isolated from surface water bodies in the territories of three former Soviet republics and 13 constituent entities of the Russian Federation in the course of 30-year monitoring and identified upon isolation as nontoxigenic V. cholerae R-variant strains has been performed. Upon re-identification, it was found that the strains belong to both epidemically dangerous (3.0 %) and non-dangerous strains (97.0 %). The range of variability was expressed in their distribution into three groups and consisted in retaining of agglutinability only with cholera RO serum in the first group (34.5 % of strains); the loss of this trait, but the acquisition of the ability to agglutinate in different combinations with O1, Ogawa or Inaba sera – in the second (16.7 %); and also in the loss of agglutinability with all diagnostic cholera sera – in the third (48.8 %). The presence of the wbeT gene in the compared V. cholerae classical R-variant strain does not exclude the presence of the genomic region for O1 antigen biosynthesis in other R-strains, possibly in a modified form, which can be clarified in further molecular-genetic studies. Alternatively, such strains are likely to be attributed to V. cholerae nonO1/nonO139. Strains of V. cholerae R-variant with different amounts of surface antigen (optical density range – from 0.088±0.002 to 1.226±0.003) have been identified. The data obtained can be used for monitoring of cholera in laboratories of regional and federal levels

Local invertibility in Sobolev spaces with applications to nematic elastomers and magnetoelasticity

We define a class of deformations in W^1,p(\u3a9,R^n), p>n 121, with positive Jacobian that do not exhibit cavitation. We characterize that class in terms of the non-negativity of the topological degree and the equality between the distributional determinant and the pointwise determinant of the gradient. Maps in this class are shown to satisfy a property of weak monotonicity, and, as a consequence, they enjoy an extra degree of regularity. We also prove that these deformations are locally invertible; moreover, the neighbourhood of invertibility is stable along a weak convergent sequence in W^1,p, and the sequence of local inverses converges to the local inverse. We use those features to show weak lower semicontinuity of functionals defined in the deformed configuration and functionals involving composition of maps. We apply those results to prove existence of minimizers in some models for nematic elastomers and magnetoelasticity

Cholera: Analysis and Assessment of Epidemiological Situation around the World and in Russia (2013–2022). Forecast for 2023

The aim of the review was to analyze and assess the epidemiological situation on cholera in the world and Russia in 2013–2022 and to make a forecast for 2023. Over the period of 2013–2022, 500 administrative territories affected by cholera were identified in various regions of 71 countries of Asia, Africa and America (the Caribbean region) with formation of 69 endemic foci in 16, 41 and 12 countries, respectively. In 2022, 1 209 301 cases of cholera were registered in 36 countries of the world. The intensity of epidemic process in Asian countries (Syria, Lebanon) increased. Unfavorable epidemiological situation on the African continent persisted. Epidemics and large outbreaks, which began in 2021–2022 due to emergency situations (ES) of social and natural character, continued. The prediction of the stability of the epidemiological situation on cholera in the territories of constituent entities of the Russian Federation (RF), given for 2022, has been confirmed. In 2022, 43 non-toxigenic strains of Vibrio cholerae О1 were isolated from surface water bodies, 8 V. cholerae nonO1/nonO139 strains – from humans. Similarity of those strains with genetically closely related ones isolated in the course of monitoring in previous years in Russia, Donetsk People’s Republic (DPR) and Zaporozhye Region was demonstrated. In 2023, the risks of importation of the infection into RF are retained. It is associated with the intensification of epidemic processes in Asian, African and Caribbean region countries. The extended border with Ukraine, to where importation of cholera from endemic countries is possible, contributes to increased degree of threat. Bioterrorism is also not excluded. The consequences of a possible cholera epidemic complication in DPR, Lugansk People’s Republic, Zaporozhye and Kherson Regions are exacerbated by social emergencies resulting in disruption of infrastructure, interruptions in water supply, etc. In the absence of implementation of the risks of importation of this infection on the territory of RF, a stable epidemiological situation on cholera will be retained. Detection of non-toxigenic V. cholerae O1 strains (including probability of clonal complexes formation), as well as strains of non-O1/non-O139 serogroups, which can be etiological factors of sporadic cases or outbreaks of diarrheal diseases, in surface water bodies is predicted

Cholera: Trends in the Development of the Epidemic Process in 2021, Forecast for 2022

The aim of the work was to summarize the results of cholera monitoring in 2021, to assess current trends in the development of the epidemic process, and to predict the epidemiological situation in the Russian Federation for 2022. It was established that within the period of 2012–2021, 4117264 cases of cholera with the spread of infection across 83 countries on all continents were registered in the world and there was a downward trend in the incidence in Asia and Africa. The dynamics of monthly morbidity in 2021 was associated with emergencies as factors of epidemiological risk. Epidemics and outbreaks of cholera were documented against the background of COVID-19 pandemic and laid a double burden on healthcare systems. At the same time, based on the overview of the results of cholera monitoring in the constituent entities of the Russian Federation, it was shown that the forecast of epidemic well-being given for 2021 was fully justified. It has been determined that the increase in the number of non-toxigenic strains of Vibrio cholerae O1 (67) isolated from water bodies compared to 2020 (25) is mainly due to the appurtenance of a number of isolates to clonal complexes. The study of phylogenetic relation has demonstrated that the detection of strains with genotypes which were previously identified in the isolates evidences the persistence potential. The identification of strains with new genotypes, which were earlier established in the strains circulating in other territories, pointed at the possibility of the occasional importations. The forecast of the epidemiological situation on cholera in Russia for 2022 is associated with the continuous existence of risks of introduction. If these epidemiological risks are not realized, a favorable epidemiological situation is predicted regarding this infection in the country. It is expected that the detection of epidemiologically insignificant strains of V. cholerae O1 in environmental water bodies, along with their clones and/or clonal complexes, will remain, including strains that may be an etiological factor in sporadic cases or outbreaks of disease