Problems of Virology

Annual epidemics of influenza result in 3–5 million cases of severe illness and more than 600 000 deaths. Severe forms of influenza are usually characterized by vascular endothelial cells damage. Thus, influenza A viruses, including subtypes A(H1N1)pdm09, A(H3N2), as well as highly pathogenic avian influenza viruses, can infect the vascular endothelium, leading to activation and subsequent dysfunction of these cells. In turn, endothelial dysfunction resulting in systemic morphofunctional changes of endothelial cells, which leads to impaired vascular tone, thrombosis and other complications, and is also a risk factor and profoundly implicated in the pathogenesis of many cardiovascular diseases. Thus, endothelial dysfunction is an important aspect of the pathogenesis of severe influenza, which must be considered in the pathogenetic therapy of this infectious disease.

The aim of the review is to analyze the causes and specify mechanisms of development of endothelial activation and dysfunction caused by influenza A virus.

Introduction. Varicella-Zoster virus (VZV) is a highly contagious alpha-herpes virus. The diagnosis of chickenpox remains a difficult task especially in cases of breakthrough chickenpox, so the development of reliable laboratory tests is necessary. The simplest and most sensitive serological test for detecting antibodies in human and animal sera is the passive hemagglutination reaction (PHAR).

The aim. To develop of a simple, highly sensitive and specific serological tests for the detection of antibodies to VZV in human and animal blood sera.

Materials and methods. Human and animal cell cultures; various strains of VZV; human and animal immune sera; monoclonal antibody to VZV glycoprotein (GP) E. Formalin-treated erythrocytes of sheep, chickens and goats, sensibilised with GP of VZV from a virus-containing supernatant were used for PHAR.

Results. Cell cultures with the maximum cytopathic effect at VZV infection were selected. A simple original method for obtaining virus-specific VZV GPs using lectins has been developed. Purified GPs were obtained by their elution from sheep erythrocytes after adsorption. The activity of VZV GP was confirmed in PHAR by an antibody diagnostic assay using formalin-treated sheep erythrocytes sensibilised using monoclonal antibodies to GP E of the “vOka” VZV strain (USA). Using GPs from different VZV strains, PHAR test and GP-based enzyme-linked immunosorbent assay (gpELISA) have been developed to detect antibodies in human and animal immune sera. These tests have high sensitivity, specificity and lack of cross-reactivity.

Conclusion. A highly specific, sensitive and reproducible tests for the detection of antibodies to VZV have been developed.

Introduction. Omsk hemorrhagic fever (OHF) is a severe disease identified in the 1940s in Western Siberia, Russia. Disease is caused by the OHF virus, which belongs to the genus Orthoflavivirus.

The purpose of the work. Analysis of changes in the genome associated with the isolation of OHF virus strains in laboratory animals (Mus musculus).

Materials and methods. Whole-genome nucleotide sequences of OHF virus strains from the working collection of the laboratory of arboviral infections of the department of natural focal viral infections of the Omsk Research Institute of Natural Focal Infections of Rospotrebnadzor were used in the study, as well as sequences from GenBank. Assessment of adaptive changes in the genome of the OHF virus was carried out using discriminant analysis methods, analyzing the composition and localization of emerging substitutions in viral RNA sequences obtained during the adaptation of viruses to the mouse organism as a result of passaging. Linked nucleotide substitutions were identified by calculating the mutual information for each pair of columns in the array of aligned nucleotide sequences. In the phylogenetic analysis, the relaxed clock algorithm of the BEAST program was used.

Results. It has been shown that point substitutions during adaptation of OHF viruses to the mouse organism occur in all parts of the genome. Many of these substitutions are included in the pattern of linked substitutions identified in the genome of the OHF virus. Discriminant analysis of differences in nucleotide substitutions for groups combining sequences by the number of passages does not allow reliable discrimination between original sequences obtained from muskrat and sequences from first passages, but it recognizes well sequences from 7 or more passages, which suggests the possibility of adaptive selection of nucleotide substitutions when interacting with the body of a white mouse. Calculation of the average rate of substitutions per site per year without taking into account the occurrence of adaptive and related substitutions gives a value of 10⁻⁵, which is almost an order of magnitude different from the result when their presence is taken into account ‒ 10⁻⁴.

Conclusion. Changes in the nucleotide sequences of OHF that occur during laboratory virus preservation practices may influence the evolutionary rate values determined when analyzing these sequences and require further study.

Introduction. Cytomegalovirus (CMV) is a DNA-containing virus that is widespread worldwide and is of great importance in infectious pathology of children and adults.

The aim of this study is to evaluate the prevalence of CMV among children and immunocompromised patients in the Nizhny Novgorod region (central Russia) and to perform a phylogenetic analysis of the identified strains.

Materials and methods. DNA samples of CMV detected in frequently ill children and adult recipients of solid organs were studied. The genetic diversity of CMV was assessed for two variable genes: UL55(gB) and UL73(gN), using NGS technology on the Illumina platform. Phylogenetic trees were constructed in the MEGA X program, the reliability of the cluster topology on the trees was confirmed using the rapid bootstrap method based on the generation of 500 pseudo-replicas.

Results. Circulation of 5 CMV genotypes by gene UL55(gB) and 5 genotypes by gene UL73(gN) was established in the territory of the Nizhny Novgorod region. While genotypes gB1 and gB2 dominated both in children and in adults, genotype gB5 was detected only in children. The spectrum of gN genotypes was more diverse: genotypes gN4a and gN3b prevailed in children, and gN1 and gN4b genotypes were predominant in adults. The obtained results allowed us to establish the similarity of the landscape of CMV genotypes circulating in Russia (Nizhny Novgorod region), Brazil, China and the USA.

Conclusion. The obtained data indicate the similarity of the landscape of CMV genotypes circulating in Russia (Nizhny Novgorod region), Brazil, China and the USA: in children, the predominant genotypes are gB1 (40.0%), gB2 (33.3%), gN4a (42.8%), and gN3b (28.6%), while in adults (recipients of solid organs) genotypes gB1 (37.5%), gB2 (37.5%), gN1 (26.3%), and gN4b (26.3%) are prevailed.