A generalized analysis of the epidemiological and epizootiological situation on anthrax in the world in 2021 is presented. Provided is the forecast for the Russian Federation for 2022. In 2021, two cases of cutaneous form of anthrax were recorded in Russia among population living in the Siberian (the Republic of Tuva) and the North Caucasian (the Republic of Dagestan) Federal Districts. Epizootiological and epidemiological instability due to the infection was manifested in neighboring countries – Azerbaijan, Armenia, Kazakhstan, Kyrgyzstan, and Ukraine. Anthrax among farm and wild animals was registered in a number of countries in Asia, Africa, Europe, North and South America, and Australia. Human cases were noted mainly in Africa (Zimbabwe, Kenya, Uganda, China) and Asia (India, Indonesia, Iraq), and were caused by the contact and/or alimentary pathways of transmission of the pathogen as a result of forced slaughter of sick and/or butchering of fallen farm animals, consuming meat of sick and fallen cattle. The level of anthrax incidence among farm animals and humans in the Russian Federation in 2022 will be predetermined by the completeness of the implementation of regulated preventive measures, and, provided the strict introduction of comprehensive epizootiological and epidemiological surveillance, will be limited to sporadic cases of infection.
Introduction. The global phylogenetic population structure of Bacillus anthracis is represented by major genetic lineages (A, B and C) with nonuniform distribution of isolates, which still cannot be explained. Identification of characteristics of genomes of strains from three lineages, which can affect their spread, is of high importance. The aim of the study is to explore genomic characteristics of different genetic lineages, which may have an effect on their distribution, by using the in silico analysis of a representative subset of B. anthracis strains. Materials and methods. The whole-genome sequences of 49 B. anthracis strains and Bacillus cereus biovar anthracis CI strain were studied. The in silico analysis was performed to identify polymorphisms using BLASTn, MEGA X, Tandem Repeat Finder, Parsnp the Harvest Suite software. Results. The genome variability depended on single nucleotide polymorphisms, single-nucleotide repeats, number of tandem repeats, substitutions and indels. In strains from lineages B and C, they outnumbered 1.613.4 times and in the B. cereus biovar anthracis strain 5150 times those in B. anthracis strains from lineage A. Significant substitutions in housekeeping genes and pathogenicity factor genes caused changes in amino acid sequences in proteins significantly more frequently in B. anthracis strains from major lineages B and C. Based on the molecular typing and a multi-virulence-locus sequence typing analysis (MVLST) with a discrimination index of 0.9633, strains were classified into three major genetic lineages including groups different from the canonical group. Conclusion. The distinctive feature of B. anthracis genomes is that they have a larger number of significant nucleotide substitutions in pathogenicity factor genes and housekeeping genes of strains belonging to major lineages B and C compared to lineage A. Changes in proteins encoded by them can cause differences in ecological adaptation and in prevalence, which are higher in strains of lineage A. MVLST having a high discriminating capacity can be used as an additional method to B. anthracis molecular typing.
Introduction. Bacillus anthracis is the causative agent of anthrax, a pathogen characterized by high genetic monomorphism that complicates differentiation of strains. Thus, molecular methods for pathogen typing require the improvement. The aim of the study. To select marker SNPs for new genetic groups of B. anthracis and to develop a method for their laboratory identification using HRM PCR. Materials and methods. The core genome of 222 strains of B. anthracis from the GenBank database and 66 strains from the collection of pathogenic microorganisms of the Stavropol Anti-Plague Institute was aligned using the parsnp software. A dendrogram based on 7242 core genome SNPs was built in MEGA X software. The strains for validation of the HRM method included representatives of various genetic groups. The HRM PCR reaction was performed using the "Type-it HRM PCR Kit" and "KAPA HRM FAST qPCR Kit" and a Rotor Gene DNA thermocycler with HRM function. Data analysis and visualization were performed using custom scripts in the Python and R development environments. Results and discussion. Marker SNPs for 6 genetic groups have been identified, which make it possible to determine whether strains belong to one of 7 new subclusters. Pairs of primers were selected for the loci containing them, HRM PCR parameters were optimized for discrimination of different alleles of SNP loci, and an analysis scheme was developed. Conclusion. Thus, marker SNPs were selected to determine the genetic subclusters A.Br.CEA, A.Br.STI, A.Br.Tsiankovskii, B.Br.Europe, B.Br.Siberia, B.Br.Asia, B.Br.018, and a new laboratory method was developed for molecular subtyping of B. anthracis using HRM PCR.
The paper provides the results of analysis of the epizootiological and epidemiological situation on anthrax in the world in 2022, also, the forecast of incidence rates for the Russian Federation in 2023 is presented. In 2022, two cases of anthrax in farm animals and two cases of cutaneous form of infection in humans were registered in Russia, in the constituent entities of the North Caucasian Federal District: the Republic of Dagestan and the Stavropol Territory. The tense situation on anthrax was reported in the neighboring countries: Azerbaijan, Georgia, Kazakhstan, Kyrgyzstan, Tajikistan, Uzbekistan, and Ukraine. Epizootics of infection with the highest number of affected farm and wild animals were recorded in the countries of Africa, Asia, North America and Europe. The incidence of anthrax among people in the far abroad (mainly in Africa and Asia) was mostly associated with consuming the meat of sick and fallen farm animals, contact with infected animals, animal products. The incidence of anthrax in animals and humans in the Russian Federation in 2023 will largely depend on the scale of coverage with specific immunization of susceptible animals and persons at risk of infection and, given the strict implementation of comprehensive surveillance measures, will be limited to the registration of potentially possible single cases of infection.
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