Chemi-ionization in Solar Photosphere: Influence on the Hydrogen Atom excited States Population

In this paper, the influence of chemi-ionization processes in $H^*(n \ge 2) + H(1s)$ collisions, as well as the influence of inverse chemi-recombination processes on hydrogen atom excited-state populations in solar photosphere, are compared with the influence of concurrent electron-atom and electron-ion ionization and recombination processes. It has been found that the considered chemi-ionization/recombination processes dominate over the relevant concurrent processes in almost the whole solar photosphere. Thus, it is shown that these processes and their importance for the non-LTE modeling of the solar atmosphere should be investigated further

Rhamnose-Positive Strains of Plague Agent: Virulence and Epidemiological Significance

The aim of the review is to show the groundlessness of the unconditional assessment of rhamnose-positive strains of plague pathogen as avirulent for most species of carriers and humans and having no epidemiological significance. The main carriers of rhamnose-positive strains are several species of voles and the Mongolian pika. The vast majority of experts are of the opinion that rhamnose-positive (“vole`s” and “pika`s”) strains of Yersinia pestis are avirulent or weakly virulent for many species of warm-blooded animals and humans, and therefore have no epidemiological significance. However, in a series of experiments on infecting marmots, ground squirrels, and large gerbils with rhamnose-positive strains, some of the experimental animals fell ill acutely and died from the plague. In nature, rhamnose-positive strains have been isolated from carcasses of relatively resistant red marmots. When evaluating the epidemiological significance of rhamnose-positive strains, such an important criterion as the presence or absence of effective factors and pathways of pathogen transmission in foci of the vole and pika types is omitted. Voles and pikas are not eaten; therefore, the contact route of infecting humans in these foci is impossible. The second way of transmission of the pathogen to humans – vector-borne – is difficult due to the lack of migration of vole fleas from burrows to the surface and their low efficiency as vectors. Nevertheless, cases of human infection with rhamnose-positive strains of the plague agent in the Caucasus and Mongolia give grounds to assert that at least some rhamnose-positive strains have a sufficiently high virulence and are capable of causing infectious process in humans as well. Therefore, epidemiological surveillance in the foci of plague of the vole and pika types cannot be totally abandoned. It can be conducted according to an abbreviated scheme

Historical and Modern Views on the Problem of Specific Plague Prophylaxis

Objective of this review is to analyze diachronically paradigm shift as regards problems of specific plague prophylaxis and appreciate contribution of the present-day scientific discoveries in the sphere of plague agent investigations and peculiarities of its interaction with host organism to the solution of topical issues of vaccine development that will be safe and tangibly effective against this particularly dangerous disease. Outlined is the historical background of the conceptual evolution concerning specific plague prophylaxis and events that are landmarked with eminent scientific discoveries by A.Yersin, French researcher and microbiologist. Given are the data on the current state of plague immune-prophylaxis both in Russia and around the world. Through the prism of the latest researches that assume application of advanced technological resource of medical sciences (molecular biology, biotechnology, bioinformatics, molecular immunology) put forward is the prospective of search and construction of safe and effective anti-plague next generation vaccines

New Method of Plague Agent Lipopolysaccharide Obtaining

Put forward are two alternatives of a new method for optimization of conditions of LPS obtaining and purification from Y. pestis strains; as well as for avoiding application of poisonous and hard-to-remove reagents; for simplification and cost-cutting of the technique; and for rationalization of production waste management. This method involves preliminary salt-water extraction of bacteria, for elimination of easy-dissolving substances, with the subsequent fracturing using ultrasound in lysing buffer (0,1 M Tris-HCl, pH 8,0; 10 mmol of EDTA, 1 % Triton X-100). The first alternative for deproteinization of non-purified endotoxin is the commercial preparation of proteinase K (Sigma), the second one - an enzyme complex - proteovibrin, isolated from waste material accumulated in the process of cholera chemical bivalent vaccine production. Apart from this, introduced has been a phase of sample acidification by applying glacial acetic acid up to pH 3,2-3,4 to decontaminate LPS from nucleic acids. These two variations of the method provide for enhancement of LPS preparation quality as compared to prototype method, and for obtainment of plague agent endotoxin that is hardly distinguishable in physical-chemical properties, homogeneity, immunochemical activity and specificity from the antigen, manufactured by means of water-phenol extraction following Westphal O. technique

Variability of <i>pgm</i>‑Region Genes in <i>Yersinia pestis</i> Strains from the Caspian Sandy and Adjacent Plague Foci

The aim of the study was to compare the nucleotide sequences of pgm‑region genes in Yersinia pestis strains isolated on the territory of the Caspian sandy and adjacent plague foci in 1925–2015. Materials and methods. 65 Y. pestis strains from the Caspian sandy and adjacent plague foci were used in the work. DNA isolation was performed using the PureLink Genomic DNA Mini Kit. Whole genome sequencing was conducted in Ion S5 XL System (Thermo Fischer Scientific). Data processing was carried out using Ion Torrent Suite software package 3.4.2 and NewblerGS Assembler 2.6. To compare the obtained sequences with the NCBI GenBank database, the Blast algorithm was used. The phylogenetic analysis was performed according to the data of whole genome SNP analysis based on 1183 identified SNPs. The search for marker SNPs was performed using the Snippy 4.6 program. The phylogenetic tree was constructed using the Maximum Likelihood algorithm, the GTR nucleotide substitution model. Results and discussion. The nucleotide sequences of pgm‑region genes of 65 Y. pestis strains from the Caspian sandy and adjacent plague foci have been assessed. Single nucleotide substitutions have been identified in Y. pestis strains from the Caspian sandy and Kobystan plain-foothill foci in the hmsR, astB, ybtS, ypo1944, ypo1943, ypo1936 genes, as well as a deletion of 5 bp in the ypo1945 gene, which is characteristic of strains of one of the phylogenetic lines of Y. pestis from the foci of Caucasus and Transcaucasia, isolated in 1968–2001. The data obtained can be used to differentiate Y. pestis strains from the Caspian sandy focus, as well as to establish the directions of microevolution of the plague pathogen in this region and adjacent foci

Construction and Medical Trials of Monoclonal Immuno-Enzyme Test-System for the Detection of Encapsulated Plague Agent Strains, “EIAPESTF1-M”

Objective of the study was to develop and then conduct medical trials of the “Monoclonal immune-enzyme test-system for the detection of plague agent (“EIAPESTF1-M”).Materials and methods. Utilized were materials for carrying out sandwich EIA. MCA 1B3 to Y. pestis F1 served as diagnostic immune-reagent. To determine sensitivity and specificity of the designed immune-enzyme test-system, investigated were samples of 24 natural and genetically modified pFra+ and pFra– Y. pestis strains and 56 strains of heterologous bacteria Enterobacteriaceae family.Results and conclusions. Based on monoclonal antibodies to Yersinia pestis capsular antigen, constructed was “Monoclonal immune-enzyme test-system for the detection of plague agent (“EIAPESTF1-M”), which is characterized by high specificity and allows for the detection of encapsulated plague agent strains in biological samples and for identification of pure cultures with sensitivity of 5·105 – 1·106 mc/ml. It is highly competitive with comparator drug – “Diagnostic fluorescent absorbed equine plague immunoglobulins”, lyophilizate for diagnostic purposes, by RusRAPI “Microbe”. It possesses such advantages as objective result recording and capability of result documentation. “EIAPESTF1-M” is registered in the RF Federal Service for Surveillance in the Sphere of Healthcare and Social Development, reference No 2013/711, dated 31.05.2013 and approved for use in the territory of the Russian Federation

Effect of Azoximer Bromide on Individual Genomic and Proteomic Characteristics of the Strain during Cultivation of <i>Yersinia pestis</i> EV NIIEG

The aim of the work was to study the effect of the azoximer bromide immunoadjuvant (polyoxidonium, PO) on certain molecular-genetic and proteomic properties of Yersinia pestis EV NIIEG strain, when added to the culture medium. Materials and methods. Y. pestis EV NIIEG was grown at 28 °C for 48 hours on LB agar pH 7.2 (Miller), with and without PO (EV+PO). Whole-genome sequencing of EV and EV+PO strains was performed on the Ion S5 XG generation II platform. Whole-genome SNP analysis and search for marker SNPs were conducted in the Wombac 2.0 program. Mass-spectra of Y. pestis EV extracts and EV+PO cells were recorded using a Microflex LT mass spectrometer. Protective properties of the test cultures were evaluated by the integral ImD50 index in BALB/c mice when infected with Y. pestis 231(708). Results and discussion. Comparative analysis has not revealed deletions, insertions and single nucleotide polymorphisms in the structure of Y. pestis EV+PO strain genome leading to a violation of the production of pathogenicity, immunogenicity and ensuring the vital activity factors of the plague pathogen. The MALDI-TOF mass spectrometry has shown that Y. pestis EV+PO strains changed the intensity of 22 % of the total number of peaks in the range of 2000–20000 Da. Most of the altered peaks in the UniProtKB protein bank belong to uncharacterized proteins and metabolic proteins. At the same time, the ImD50 was 2–3.3 times lower in cultures grown with the addition of PO than in Y. pestis EV. Thus, the addition of PO to Y. pestis EV NIIEG culture medium does not cause changes in the genes of pathogenicity and vital activity support factors of plague pathogen, but modulates its protein profile, which is accompanied by an increase in the protective potential of the EV vaccine strain

Effectiveness of the “Sterius 60” SHF Radiation Installation for Disinfection of Objects Contaminated with PBA of Groups I–IV, when Working with Infected Biomodels

The aim was to evaluate the effectiveness of using the “Sterius 60” microwave disinfection system (Russia) for decontamination of objects infected with PBA of groups I–IV emerging as a result of working with infected laboratory animals.Materials and methods. Effectiveness verification of disinfection of biological waste generated as a result of the life of laboratory animals by SHF radiation was carried out in the microwave system “Sterius 60”, recommended by the manufacturer for disinfection of epidemiologically hazardous and extremely dangerous medical waste, including biological ones (classes B and C), by volumetric SHF heating. Carcasses of uninfected laboratory animals (white mice, Guinea pigs, suckling rabbits), granulated feed and bedding material (wood shavings), which are objects directly in contact with biomodels, were used as vivarium waste to be decontaminated. The following microorganisms were utilized as model test ones: Bacillus subtilus VKM B-911, Bacillus stearothermophilus VKM B-718, Bacillus licheniformis G VKM B-1711-D, Alcaligenes faecalis 415, Yersinia pestis EV, Bacillus anthracis STI. Laboratory utensils (plastic Petri dishes, porcelain mortars and pestles) were used as a mock-up chamber filler for model test microorganisms.Results and discussion. As a result of the study, data were obtained indicating that the microwave system for disinfection of medical waste “Sterius 60” is ineffective for decontamination of biological waste in laboratories working with biomodels infected with PBA of groups I–II. The established standard mode of disinfection of this system was effective only for non-spore forms of microorganisms, pathogenicity groups III–IV. Therefore, in our opinion, it is advisable to use it for decontamination of laboratory utensils infected with PBA of groups III–IV, directly at sites of waste generation

Molecular-Genetic and Phenotypic Peculiarities of Plague Agent Strains Isolated in Vietnam

Objective of the study is to investigate phenotypic and molecular-genetic features and perform whole genome sequencing of Y. pestis strains isolated in Vietnam. Materials and methods. Studied were phenotypic and genotypic peculiarities of 20 plague agent strains isolated in different prefectures of Vietnam. Carried out was SNP-analysis of the strains, sequenced were genomes of 8 Y. pestis strains. Results and conclusions. Based on the results of studies of differential biochemical characteristics all the investigated strains were attributed to oriental biovar of the main subspecies of plague agent, which was confirmed by the presence of marker indel mutation – deletion of 93 bps in glpD gene. Investigated was also the plasmid composition of the strains. On the basis of the conducted genome sequencing and SNP-analysis appurtenance of 19 out of 20 strains under examination was determined. They belong to 1.ORI2v phylogenetic branch, relative to the strains isolated in Yunnan Province, China, which points to their common origin. Identified was a marker SNP and developed the method of SNP-typing for 1.ORI2v strains from Vietnam