Vol 68, No 3 (2023)

Exosomes are extracellular vesicles of endosomal origin, with a bilayer membrane, 30–160 nm in diameter. Exosomes are released from cells of different origins and are detected in various body fluids. They contain nucleic acids, proteins, lipids, metabolites and can transfer the contents to recipient cells. Exosome biogenesis involves cellular proteins of the Rab GTPase family and the ESCRT system, which regulate budding, vesicle transport, molecule sorting, membrane fusion, formation of multivesicular bodies and exosome secretion. Exosomes are released from cells infected with viruses and may contain viral DNA and RNA, as well as mRNA, microRNA, other types of RNA, proteins and virions. Exosomes are capable of transferring viral components into uninfected cells of various organs and tissues. This review analyzes the impact of exosomes on the life cycle of widespread viruses that cause serious human diseases: human immunodeficiency virus (HIV-1), hepatitis B virus, hepatitis C virus, SARS-CoV-2. Viruses are able to enter cells by endocytosis, use molecular and cellular pathways involving Rab and ESCRT proteins to release exosomes and spread viral infections. It has been shown that exosomes can have multidirectional effects on the pathogenesis of viral infections, suppressing or enhancing the course of diseases. Exosomes can potentially be used in noninvasive diagnostics as biomarkers of the stage of infection, and exosomes loaded with biomolecules and drugs - as therapeutic agents. Genetically modified exosomes are promising candidates for new antiviral vaccines.

Introduction. The search for affordable and accurate predictors of the outcome of COVID-19 is extremely important, as it provides the possibility to effectively correct the patient treatment tactics.

Aim of the study. To develop simple and accurate criteria based on the dynamics of red blood counts that predict the outcome of COVID-19.

Materials and methods. Observations were carried out in 125 patients with severe and extremely severe COVID-19, in whom indicators characterizing the state of red blood were determined in dynamics on days 1, 5, 7, 10, 14 and 21 after the hospitalization. ROC analysis was performed to calculate the threshold predictive values for survival and mortality.

Results. The total number of erythrocytes and the level of hemoglobin in severe and extremely severe patients did not go beyond the acceptable limits, although showed a tendency to decrease in the group of fatal cases. On the 1^st and 21^st days, the number of MacroR in the deceased patients was reduced compared to those in group of survivors. It has been established that the RDW-CV test can predict the outcome of the COVID-19 with a high degree of probability at a relatively early stage of disease. RDW-SD test can be an additional predictive criterion of COVID-19 outcome.

Conclusion. The RDW-CV test can be used as an effective predictor of disease outcome in patients with severe COVID-19.

Introduction. Intranasal vaccination using live vector vaccines based on non-pathogenic or slightly pathogenic viruses is the one of the most convenient, safe and effective ways to prevent respiratory infections, including COVID-19. Sendai virus is the best suited for this purpose, since it is respiratory virus and is capable of limited replication in human bronchial epithelial cells without causing disease.

The aim of the work is to design and study the vaccine properties of recombinant Sendai virus, Moscow strain, expressing secreted receptor-binding domain of SARS-CoV-2 Delta strain S protein (RBDdelta) during a single intranasal immunization.

Materials and methods. Recombinant Sendai virus carrying insertion of RBDdelta transgene between P and M genes was constructed using reverse genetics and synthetic biology methods. Expression of RBDdelta was analyzed by Western blot. Vaccine properties were studied in two models: Syrian hamsters and BALB/c mice. Immunogenicity was evaluated by ELISA and virus-neutralization assays. Protectiveness was assessed by quantitation of SARS-CoV-2 RNA in RT-PCR and histological analysis of the lungs.

Results. Based on Sendai virus Moscow strain, a recombinant Sen-RBDdelta(M) was constructed that expressed a secreted RBDdelta immunologically identical to natural SARS-CoV-2 protein. A single intranasal administration of Sen-RBDdelta(M) to hamsters and mice significantly, by 15 and 107 times, respectively, reduced replicative activity of SARS-CoV-2 in lungs of animals, preventing the development of pneumonia. An effective induction of virus-neutralizing antibodies has also been demonstrated in mice.

Conclusion. Sen-RBDdelta(M) is a promising vaccine construct against SARS-CoV-2 infection and has a protective properties even after a single intranasal introduction.

Introduction. Following the successful eradication of smallpox, mass vaccination against this disease was discontinued in 1980. The unvaccinated population continues to be at risk of infection due to military use of variola virus or exposure to monkeypox virus in Africa and non-endemic areas. In cases of these diseases, rapid diagnosis is of great importance, since the promptness and effectiveness of therapeutic and quarantine measures depend on it.

The aim of work is to develop a kit of reagents for enzyme-linked immunosorbent assay (ELISA) for fast and highly sensitive detection of orthopoxviruses (OPV) in clinical samples.

Materials and methods. The efficiency of virus detection was evaluated by single-stage ELISA in the cryolisate of CV-1 cell culture samples infected with vaccinia, cowpox, rabbitpox, and ectromelia viruses, as well as in clinical samples of infected rabbits and mice.

Results. The method of rapid ELISA was shown to allow the detection of OPV in crude viral samples in the range of 5.0 × 10²–5.0 × 10³ PFU/ml, and in clinical samples with a viral load exceeding 5 × 10³ PFU/ml.

Conclusions. The assay involves a minimum number of operations and can be performed within 45 minutes, which makes it possible to use it in conditions of a high level of biosecurity. Rapid ELISA method was developed using polyclonal antibodies, which significantly simplifies and reduces the cost of manufacturing a diagnostic system.

Introduction. The countries of Central Asia, including Kyrgyzstan, are characterized by high prevalence and morbidity of HCV infection. Identification of HCV genotype and mutations associated with resistance to direct-acting antiviral (DAA) plays an important role either in conducting molecular epidemiological studies or choosing the treatment tactics.

The aim of the work was to research of the genotype diversity of HCV variants circulating in Kyrgyzstan and the identification among them the mutations associated with the development of resistance to DAA.

Materials and methods. 38 serum samples from HCV-infected residents of Kyrgyzstan were analyzed in this study. The nucleotide sequences of viral gene fragments (NS3, NS5A, NS5B) were determined by Sanger’s sequencing and deposited in the international GenBank database under the numbers ON841497–ON841534 (NS5B), ON841535–ON841566 (NS5A), and ON841567–ON841584 (NS3).

Results. The HCV subtypes 1b (52.6%; 95% CI 37.3–67.5%), 3a (44.8%; 95% CI 30.2–60.2%) and 1a (2.6%; 95% CI 0.5–13.4%) are circulating in Kyrgyzstan. 37% (95% CI 19–59%) of subtype 1b isolates had C316N mutation in the NS5A gene; 46% (95% CI 23–70%) had F37L mutation in the NS5A gene; 45% (95% CI 22–72%) had Y56F mutation in the NS3 gene. Among subtype 3a isolates, resistance-associated mutations in NS5B fragment were not found. 22% (95% CI 9–45%) of subtype 3a sequences had a Y93H mutation in the NS5A gene. A combination of Y56F + Q168 + I170 mutations was identified among all sequences of NS3 gene. DAA resistance mutations were not found in NS3, NS5A, NS5B genes of subtype 1a sequence.

Conclusion. A rather high prevalence of mutations associated with resistance or significant decrease in sensitivity to DAA among HCV sequences from Kyrgyzstan was shown. Updating of data on HCV genetic diversity is necessary for timely planning of measures to combat epidemic.