Olga Y. Slovareva
Pages 1-12 (Rus), 13-23 (Eng)
Grain export is an important branch of the food business in the Russian Federation. The countries of Europe, Asia, Africa, and South America are importers of Russian grain. Each importing country has its own requirements for the phytosanitary condition of imported products. One important requirement for importers is the absence of pathogens that can cause bacterial diseases of grain crops, such as Pectobacterium rhapontici, Rathayibacter tritici, Pseudomonas fuscovaginae, Pseudomonas syringae pvs., Acidovorax avenae subsp. avenae, Xanthomonas translucens pvs., Rathayibacter rathayi, and Pseudomonas cichorii. Reliable information on the distribution of these bacterial strains in the Russian Federation is limited. Methods for the isolation and identification of these bacterial pathogens have not been developed to date, which increases the risk of the spread of phytopathogens that could cause significant economic harm to agriculture.
The purpose of this study was to isolate and identify the causative agents of bacterial diseases of wheat and barley. In order to do this, we collected samples of plant material of wheat and barley in the Rodionovo-Nesvetaysky, Myasnikovsky, Zernogradsky, Azovsky, and Martynovsky districts of the Rostov Oblast. Various bacterial strains were isolated from the obtained samples using the appropriate cultural media. The strains were tested by polymerase chain reaction (PCR) using primers designed for the 16S ribosomal RNA (PSF/PSR and 8UA/519B) and SyD1/SyD2 primers selected for the Pseudomonas syringae genome (GenBank CP047267.1) with subsequent sequencing according to the Sanger method. As a result, the following bacterial strains were isolated and identified from wheat and barley samples: Curtobacterium sp., Paenibacillus sp., Enterobacteriaceae, Pseudomonas azotoformans, P. poae, P. azotoformans, P. hibiscicola, P. fluorescens, Stenotrophomonas sp., P. syringae pv. syringae, P. syringae pv. atrofaciens, Bacillus sp., Erwinia sp., Pantoea sp., and Pantoea agglomerans.
Kirill A. Vasilyev, Anna-Polina S. Shurygina, Marina A. Stukova, Andrej Y. Egorov
Pages 24-33 (Eng)
Influenza viruses with truncated NS1 protein stimulate a more intensive innate immune response compared to their wild type counterparts. Here, we investigate how the shortening of the NS1 protein influence the immunogenicity of the conserved T-cellular epitopes of influenza virus. Using flow cytometry, we showed that the intraperitoneal immunization of mice with influenza virus encoding 124 N-terminal amino acid residues of the NS1 protein (A/PR8/NS124) induced higher levels of CD8+ T-cells recognizing immunodominant (NP366-374) and sub-immunodominant (NP161-175, NP196-210, HA323-337, HA474-483, NA427-433) epitopes compared to immunization with the virus expressing full-length NS1 (A/PR8/full NS). It is noteworthy that the response to the immunodominant influenza epitope NP366-374 was achieved with the lower immunization dose of A/PR8/NS124 virus compared to the reference wild type strain. Despite the fact that polyfunctional CD8+ effector memory T-lymphocytes simultaneously producing two (IFNγ and TNFα) or three (IFNγ, IL2, and TNFα) cytokines prevailed in the immune response to both viruses, the relative number of such T-cells was higher in A/PR8/NS124-immunized mice. Furthermore, we have found that polyfunctional populations of lymphocytes generated upon the immunization of mice with the mutant virus demonstrated an increased capacity to produce IFNγ compared to the corresponding populations derived from the A/PR8/full NS-immunized mice. Therefore, immunization with the attenuated influenza virus encoding truncated NS1 protein ensures a more potent CD8+ T-cell immune response.
Andrej Egorov, Julia Romanova
Pages 34-41 (Rus), 42-48 (Eng)
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) originated in November 2019 in China and quickly spread throughout the world causing a disease named COVID-19. An analysis of the epidemiological data on morbidity and mortality caused by SARS-CoV-2 shows that, in some countries, namely Belgium, UK, France, Italy, the Netherlands, and Spain, an increased case fatality rate (CFR) was noticed compared to the rest of the world. The CFR, calculated as the number of deaths from the total number of the cases, ranges in these countries from 10.22% to 15.8% according to the Center for Evidence-Based Medicine (CEBM). At the same time, in the countries of Central and Northern Europe, this parameter varies between 3.78% and 4.94%. This significant heterogeneity in CFR between countries has not been given a convincing explanation yet. It was found that the precursor of SARS-CoV-2 is a virus circulating in bats in China. The mutations that occurred in this virus altered its receptor specificity, thereby enabling viral infection in humans. Bats are highly resistant to viral infections due to their robust interferon system and a reduced level of inflammatory reactions. Viruses replicate in these animals up to high titers without any substantial harm to their health. As a result, bats represent a large reservoir of viruses with the potential to infect other animals, including humans. The infection of people with bat (or human) betacoronaviruses can lead to the formation of memory B-cells that provide an accelerated antibody response to cross-reactive epitopes upon subsequent infection. The early emergence of neutralizing antibodies in SARS-CoV-2 patients correlates with the severity of the disease and the likelihood of a fatal outcome. The antibody-dependent enhancement (ADE) of infection/disease known for various viruses, including SARS-CoV-1 and MERS-CoV, may be a possible cause of this phenomenon. In this article, we suggest a close connection between the distribution areas of bats carrying SARS-CoV-1-like viruses and the CFR from COVID-19.
Mariya G. Shvydkaya, Aleksandr M. Zatevalov, Dzhamilya T. Dzhandarova, Sergey D. Mitrokhin
Pages 49-53 (Rus), 54-58 (Eng)
Patients in pediatric oncological hospitals are at risk of developing a Clostridium difficile infection. The purpose of this study was to determine the risk of developing a Clostridium difficile infection in patients who are treated with antibiotics of different classes and their combinations by way of a retrospective analysis of 122 patient records. It was shown that the administration of antibacterial chemotherapeutic drugs that belong to the classes of nitrofurans (enterofuryl), sulfonamides (biseptol), cephalosporins, and macrolides/azalides significantly increased the risk of developing a Clostridium difficile infection in pediatric patients. On the contrary, treatment with antibiotics of different classes, such as linezolid, colistin, and metronidazole, significantly reduced the risk of developing a Clostridium difficile infection. The use of penicillins, aminoglycosides, fluoroquinolones, glycopeptides, and carbapenems was not associated with the risk of developing a Clostridium difficile infection in pediatric patients. The administration of one or two antimicrobial drugs of different classes increased the risk of developing a Clostridium difficileinfection while a combination of three different types of antimicrobial drugs lowered the rate of this infection in pediatric patients.
Pages 59-71 (Eng)
Daptomycin is the only lipopeptide antibiotic that is widely used in clinical practice. It was discovered by Eli Lilly and then studied and commercialized by Cubist Pharmaceuticals in 2003. Although this antibiotic has been used for 17 years, the debate over its mechanism of action is ongoing. In this paper, we discuss the different hypotheses on the mode of action of this antibiotic with a primary focus on the bacterial membrane permeabilization as the main mechanism of action. By comparing the experimental data on the oligomerization of daptomycin in membranes with properties of self-assembling cyclic peptides, we conclude that the structure of daptomycin oligomer should resemble the structures of peptide nanotubes that serve as ion channels in membranes.