Vol 70, No 5 (2025)

For nearly 80 years since the discovery of the first virus by the Russian scientist D.I. Ivanovsky, it has been recognized that all organisms of Earth’s biosphere serve as natural hosts for viruses. Viruses, grouped within the informal domain Vira, infect all three domains of cellular life: archaea – Archaea, bacteria – Bacteria, and eukaryotes – Eucarya (algae, fungi, protozoa, plants, invertebrates, and vertebrates). The formation of viral population gene pools through interactions with the gene pools of their hosts has taken place under changing environmental conditions over 3.5 billion years, giving rise to the vast diversity of the virosphere. The accumulation of data on the Earth’s virosphere, facilitated by the advent of high-throughput sequencing technologies (NGS), has necessitated a reassessment of approaches to virus classification and, since 2018, has led to a reform of viral taxonomy through the introduction of higher taxonomic ranks (megataxonomy). As of September 2025, the International Committee on Taxonomy of Viruses (ICTV) recognizes 15 taxonomic ranks for viruses, the most significant being: realm – 7, kingdom – 11, phylum – 23, class – 49, order – 93, family – 368, genus – 3769, and species – 16,215. Ongoing advances in metagenomics, metatranscriptomics, and the global ecology of the virosphere will inevitably drive further changes in viral taxonomy and megataxonomy. These developments are of fundamental importance for understanding the evolution of the biosphere and of practical relevance for developing new strategies to strengthen biological security and to mitigate the consequences of epidemic emergencies associated with emerging and reemerging infections.

The review describes certain viral vectors and considers various methods for constructing recombinant viruses with special attention paid to the homologous recombination and CRISPR/Cas9 system, and also describes the capabilities of using various cloning vectors (different plasmids, BAC etc.). The review also presents a comparative analysis of the effectiveness and safety of using various viral vectors, both for creating recombinant vaccines and for obtaining oncolytic viruses, as well as medicines for gene therapy.

Introduction. Adenovirus infection occurs globally in the form of sporadic cases and isolated outbreaks. Human adenovirus type 55 (HAdV-55), endemic in China and South Korea, causes acute respiratory viral infections (ARVI) of varying severity, both among the civilian population and in military units in different countries of the world. Genomic research facilitates reliable identification of HAdV-55.

The aim of this study was to identify HAdV isolated in Moscow in 2022, as well as to conduct whole-genome sequencing and comparative genomic research.

Materials and methods. HAdV-55 was isolated from a sample of a patient hospitalized with pneumonia and analyzed using restriction fragment length polymorphism analysis and whole-genome sequencing. Bioinformatics comparative analysis was performed on a sample of sequences of 83 isolates.

Results. The whole-genome sequencing of first isolated in Russia HAdV-55 was conducted. The sequence of isolate SCV3008:Ad55 was deposited in GenBank (Accession Number PQ641625). Unique mutations in the SCV3008:Ad55 genome were identified, one of which resulted in a conservative T29A substitution in the penton that did not affect its functions. Phylogenetic analysis showed clustering of SCV3008:Ad55 with isolates of clade II, which included representatives of 7 countries on different continents, indicating a wide distribution of HAdV-55. Isolates from endemic regions of China and South Korea formed separate clades. The study of microsatellite length polymorphism in untranslated regions of the genome became an additional tool for distinguishing closely related genomes.

Conclusion. The obtained genomic information laid the foundation for further monitoring for HAdV-55 in Russia and demonstrated the informativeness and significance of whole-genome studies for monitoring adenoviruses. The development and implementation of genotyping methods aimed at detecting HAdV-55 and other clinically relevant genotypes will significantly improve the effectiveness of the diagnosis of adenovirus infections with the threat of developing bronchopneumonia.

Introduction. Hepatitis B and C viruses cause chronic infections leading to liver cirrhosis and hepatocellular carcinoma.

This study aimed to determine the seroprevalence of hepatitis B and C viruses and the potential risk factors which might influence the prevalence among health care workers (HCWs) in Brazzaville, Republic of Congo.

Materials and methods. We conducted a cross-sectional study from June to November 2022 among HCWs from the Talangaï and Makélékélé referral hospitals, Brazzaville. 107 HCWs were included and serological screening was carried out using rapid screening tests followed by the ELISA technique, after completing a survey questionnaire.

Results. The mean age was 36.56 ± 11.62 years with a female predominance of 1 : 0.36 sex ratio, laboratory technicians were the most represented socio-professional category. Seroprevalence of HBV was 7.48% and that of HCV was 3.74%. During their service, 40% have already been the victims of blood exposure accidents and have 7 times more risk of contracting HBV (odd ratio [OR] = 7.01 (95% Confidence interval [CI] 1.54–31.96); p = 0.01).

Conclusion. These data show that hepatitis B and C viruses are still endemic among HCWs in Republic of Congo. We can conclude that the health care sector is a high-risk profession due to infection with hepatitis B and C viruses. It is therefore necessary to improve the health and safety conditions of HCWs, implement new strategies to reduce occupational exposure to blood and body fluids, and reduce viral contamination by hepatitis B and C.

Introduction. The antiviral action of a number of drugs is associated with their modification of the lipid membrane of viruses. One of the possible mechanisms of such modification of the viral membrane is the extraction of cholesterol from the membranes of virions.

Objective of the study. A method has been developed for determining the infectious and hemagglutinating titer of avian influenza virus by changing the microviscosity of the viral membrane after incubation with phospholipid modifiers, using cholesterol-free liposomes consisting of phosphatidylcholine and phosphatidylethanolamine in a molar ratio of 1 : 2 for 48 hours as an example.

Materials and methods. The extraction process was confirmed by two methods: gel filtration with radioactively labeled liposomes and virions, and by changing the polarization value of the fluorescent probe 1-anilinonaphthalene-8-sulfonate anion (8-ANS) in the viral membrane.

Results. A correlation was found between the change in infectious and hemagglutinating titer and the microviscosity of the viral membrane.

Conclusion. In this regard, it seems possible to use this dependence to determine the infectious and hemagglutinating activity of the influenza virus within one serotype in clinical laboratory diagnostics, using various fluorescent probes. It should be noted that not only liposomes of a certain composition can be used as lipophilic modifiers of the viral membrane, but also such compounds as ethylene glycol, erythritol, glycerol.