Mutations arising in influenza viruses that have undergone immune pressure may promote a successful spread of mutants in nature. In order to evaluate the variability of nonpathogenic influenza virus ...A/duck/Moscow/4182-C/2010(H5N3) and to determine the common epitopes between it and highly pathogenic H5N1 avian influenza viruses (HPAIV), a set of escape mutants was selected due to action of MABs specific against A/chicken/Pennsylvania/8125/83(H5N2), A/Vietnam/1203/04(H5N1) and A/duck/Novosibirsk/56/05(H5N1) viruses. The complete genomes of escape mutants were sequenced and amino acid point mutations were determined in HA, NA, PA, PB1, PB2, M1, M2, and NP proteins. Comprehensive analysis of the acquired mutations was performed using the Influenza Research Database (https://www.fludb.org) and revealed that all mutations were located inside short linear epitopes, in positions characterized by polymorphisms. Most of the mutations found were characterized as substitutions by predominant or alternative amino acids existing in nature. Antigenic changes depended only on substitutions at positions 126, 129, 131, 145 and 156 of HA (H3 numbering). The positions 126, 145 and 156 were common for HA/H5 of different phylogenetic lineages of H5N1 HPAIV (arisen from A/goose/Guangdong/1/96) and low pathogenic American and Eurasian viruses. Additionally, mutation S145P increased the temperature of HA heat inactivation, compared to wild-type, as was proved by reverse genetics. Moreover, nonpathogenic A/duck/Moscow/4182-C/2010(H5N3) and H5N1 HPAI viruses have the same structure of short linear epitopes in HA (145-157) and internal proteins (PB2: 186-200, 406-411; PB1: 135-143, 538-546; PA: 515-523; NP: 61-68; M1: 76-84; M2: 45-53). These facts may indicate that H5 wild duck nonpathogenic virus could be used as vaccine against H5N1 HPAIV. Keywords: avian influenza virus; H5 hemagglutinin; escape mutants; genetic analysis; phenotypic properties; site-specific mutagenesis.
Cryo-electron microscopy (cryo-EM) is indispensable for the structural studies of enveloped viruses: dangerous pathogens of humans and animals. Yet, it requires highly specialized equipment as well ...as careful sample preparation. In this work, the capabilities of a JEOL JEM-2100 transmission electron microscope equipped with a cryo-transfer holder are used, and preliminary cryo-EM data for influenza A and B virus strains and SARS-CoV-2 inactivated with beta-propiolactone are presented. Image analysis allows us to (1) distinguish “empty” viral particles from “full” ones (containing nucleocapsid); (2) visualize the lipid bilayer of the viral envelope; (3) identify influenza virus surface antigens and the M1 protein layer combined with the inner lipid monolayer; and (4) distinguish different morphology of S-spikes on the surface of inactivated SARS-CoV-2 virions. The developed approach provides good image quality for both fundamental and applied research.
Newcastle disease virus (NDV) is an enveloped paramyxovirus. The matrix protein of the virus (M-NDV) has an innate propensity to produce virus-like particles budding from the plasma membrane of the ...expressing cell without recruiting other viral proteins. The virus predominantly infects the host cell via fusion with the host plasma membrane or, alternatively, can use receptor-mediated endocytic pathways. The question arises as to what are the mechanisms supporting such diversity, especially concerning the assembling and membrane binding properties of the virus protein scaffold under both neutral and acidic pH conditions. Here, we suggest a novel method of M-NDV isolation in physiological ionic strength and employ a combination of small-angle X-ray scattering, atomic force microscopy with complementary structural techniques, and membrane interaction measurements to characterize the solution behavior/structure of the protein as well as its binding to lipid membranes at pH 4.0 and pH 7.0. We demonstrate that the minimal structural unit of the protein in solution is a dimer that spontaneously assembles in a neutral milieu into hollow helical oligomers by repeating the protein tetramers. Acidic pH conditions decrease the protein oligomerization state to the individual dimers, tetramers, and octamers without changing the density of the protein layer and lipid membrane affinity, thus indicating that the endocytic pathway is a possible facilitator of NDV entry into a host cell through enhanced scaffold disintegration.
The matrix protein of the Newcastle disease virus (NDV) is one of the most abundant viral proteins that regulates the formation of progeny virions. NDV is an avian pathogen that impacts the economics of bird husbandry due to its resulting morbidity and high mortality rates. Moreover, it belongs to the
subfamily of the
family of
that include dangerous representatives such as respiratory syncytial virus, human parainfluenza virus, and measles virus. Here, we investigate the solution structure and membrane binding properties of this protein at both acidic and neutral pH to distinguish between possible virus entry pathways and propose a mechanism of assembly of the viral matrix scaffold. This work is fundamental for understanding the mechanisms of viral entry as well as to inform subsequent proposals for the possible use of the virus as an adequate template for future drug or vaccine delivery.
Biolistics is one of the widely used methods to deliver nucleic acids into plant cells. In this work, we optimized the protocol for biolistic transformation of
Nicotiana tabacum
with the gene gun ...PDS-1000/He Biolistic Particle Delivery System. The Green Fluorescent Protein (GFP) gene was used as a marker. The optimal parameters for the transformation of
N. tabacum
leaf cells were determined as: pressure, 1350 psi; tungsten particle size, 1.3 μm; plasmid DNA purification method, ethanol re-precipitation. The results should be useful for the development of biolistic transformation protocols for plant cells, including application for plant genome editing of agricultural species.
The search‐coil magnetometer (SCM) measures the magnetic signature of solar wind fluctuations with three components in the 3 Hz–50 kHz range and one single component in the 1 kHz–1 MHz range. This ...instrument is important for providing in situ observations of transients caused by interplanetary shocks and reconnection, for the identification of electromagnetic wave modes in plasmas and the determination of their characteristics (planarity, polarization, ellipticity, and k‐vector) and for studying the turbulent cascade in the kinetic range. Two similar triaxial search‐coils have been built for the Parker Solar Probe and Solar Orbiter missions. Here we describe the science objectives of both missions which led to the SCM design and present the characteristics of the two instruments.
Key Points
The search‐coil magnetometer (SCM) measures AC magnetic fields onboard the Parker Solar Probe and Solar Orbiter satellites
This instrument is important for addressing the problem of coronal heating, solar wind formation and particle acceleration by means of wave mode identification
Both SCM instruments have been launched and are now operating
Introduction. The WHO regularly updates influenza vaccine recommendations to maximize their match with circulating strains. Nevertheless, the effectiveness of the influenza A vaccine, specifically ...its H3N2 component, has been low for several seasons.
The aim of the study is to develop a mathematical model of cross-immunity based on the array of published WHO hemagglutination inhibition assay (HAI) data.
Materials and methods. In this study, a mathematical model was proposed, based on finding, using regression analysis, the dependence of HAI titers on substitutions in antigenic sites of sequences. The computer program we developed can process data (GISAID, NCBI, etc.) and create real-time databases according to the set tasks.
Results. Based on our research, an additional antigenic site F was identified. The difference in 1.6 times the adjusted R2, on subsets of viruses grown in cell culture and grown in chicken embryos, demonstrates the validity of our decision to divide the original data array by passage histories. We have introduced the concept of a degree of homology between two arbitrary strains, which takes the value of a function depending on the Hamming distance, and it has been shown that the regression results significantly depend on the choice of function. The provided analysis showed that the most significant antigenic sites are A, B, and E. The obtained results on predicted HAI titers showed a good enough result, comparable to similar work by our colleagues.
Conclusion. The proposed method could serve as a useful tool for future forecasts, with further study to confirm its sustainability.
The Republic of Sakha (Yakutia) possessing a vast territory located in various climatic zones and a developed network of water bodies is exposed to a wide range of natural emergency situations. Among ...them, spring-summer floods are the most frequent and bringing enormous damage, causing inundations of vast areas and national economy objects, which determines relevance of development and improvement of flood forecast methods for implementation of timely measures to prevent and reduce an inundation risk.Artificial neural networks have proven their effectiveness in solving various forecast problems, especially when using statistical data. In particular, usage of a neural network approach based on the forecast of a time series from previous values gives good results. The artificial neural networks, unlike statistical methods of analysis, are based on parallel data processing, have an ability of self-learning and recognition of nonlinear relationships between input and output data sets. A choice of parts of the Lena river to predict maximum water levels during the floods was determined based on locations of potentially hazardous objects, the inundation of which can cause the considerable material damage. On the basis of the hydrological data obtained during 70 years, the neural network models are obtained, which make it possible to predict flood hazards from the spring floods, two variants of the transformed initial data are considered and different network structures are compared. Relative errors of the forecasts obtained during the work vary considerably (7-20%), which indicates necessity for the processing of the initial data and careful selection of the structure.
Tetra-
n-butylammonium (TBA) salts of the cobalt-monosubstituted Keggin polyoxometalate (Co-POM), TBA
4HPW
11CoO
39 (
I) and TBA
5PW
11CoO
39 (
II), have been prepared and characterized by using ...elemental analysis, potentiometric titration, IR, UV–vis,
31P NMR, and cyclic voltammetry. Different modes of heterogenization of the Co-POM, including anchoring to both NH
2- and NH
3
+-modified mesoporous silica surfaces and sol–gel synthesis, have been performed. The resulting solid catalysts were characterized by N
2-adsorption measurements, elemental analysis, DR-UV–vis, and FT-IR spectroscopy. The activity of the solid Co-POM materials to catalyze aerobic oxidation of two representative aldehydes, isobutyraldehyde (IBA) in MeCN and formaldehyde in H
2O under mild conditions (20–40
°C, 1 atm of air), was assessed and compared with the catalytic activity of the corresponding homogeneous Co-POMs. An emphasis has been placed on leaching tests and catalyst recycling. The effect of protonation of the amine-modified silica surface or the Co-POM on the loading, stability, and activity of the Co-POM solid catalyst was evaluated.
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