[Influence of siRNA complexes on the reproduction of influenza A virus (Orthomyxoviridae: Alphainfluenzavirus) in vivo].

INTRODUCTION: Influenza is one of the most pressing global health problems. Despite the wide range of available anti-influenza drugs, the viral drug resistance is an increasing concern and requires the search for new approaches to overcome it. A promising solution is the development of drugs with action that is based on the inhibition of the activity of cellular genes through RNA interference. AIM: Evaluation in vivo of the preventive potential of miRNAs directed to the cellular genes FLT4, Nup98 and Nup205 against influenza infection. MATERIALS AND METHODS: The A/California/7/09 strain of influenza virus (H1N1) and BALB/c mice were used in the study. The administration of siRNA and experimental infection of animals were performed intranasally. The results of the experiment were analyzed using molecular genetic and virological methods. RESULTS: The use of siRNA complexes Nup98.1 and Nup205.1 led to a significant decrease in viral reproduction and concentration of viral RNA on the 3rd day after infection. When two siRNA complexes (Nup98.1 and Nup205.1) were administered simultaneously, a significant decrease in viral titer and concentration of viral RNA was also noted compared with the control groups. CONCLUSIONS: The use of siRNAs in vivo can lead to an antiviral effect when the activity of single or several cellular genes is suppressed. The results indicate that the use of siRNAs targeting the cellular genes whose expression products are involved in viral reproduction is one of the promising methods for the prevention and treatment of not only influenza, but also other respiratory infections.

[Comparative study of Wuhan-like and omicron-like variants of SARS-CoV-2 in experimental animal models].

INTRODUCTION: The variability of SARS-CoV-2 appeared to be higher than expected, the emergence of new variants raises concerns. The aim of the work was to compare the pathogenicity of the Wuhan and BA.1.1/Omicron variants in BALB/c mice and Syrian hamsters. MATERIALS AND METHODS: The study used strains of SARS-CoV-2: Dubrovka phylogenetically close to Wuhan-Hu-1, and LIA phylogenetically close to Omicron, BALB/c mice, transgenic mice B6.Cg-Tg(K18-ACE2)2Prlmn/HEMI Hemizygous for Tg(K18-ACE2)2Prlmn, Syrian golden hamsters. Animals were infected intranasally, pathogenicity was estimated by a complex of clinical, pathomorphological and virological methods. RESULTS: Comparative studies of SARS-CoV-2 Dubrovka and LIA strains on animal models demonstrated their heterogeneous pathogenicity. In parallel infection of BALB/c mice with Dubrovka and LIA variants, the infection proceeded without serious clinical signs and lung damage. Infection with the LIA strain resulted to a systemic disease with a high concentration of viral RNA in the lungs and brain tissues of animals. The presence of viral RNA in mice infected with the Dubrovka strain was transient and undetectable in the lungs by day 7 post-infection. Unlike the mouse model, in hamsters, the Dubrovka strain had a greater pathogenicity than the LIA strain. In hamsters infected with the Dubrovka strain lung lesions were more significant, and the virus spread through organs, in particular in brain tissue, was observed. In hamsters infected with the LIA strain virus was not detected in brain tissue. CONCLUSION: The study of various variants of SARS-CoV-2 in species initially unsusceptible to SARS-CoV-2 infection is important for monitoring zoonotic reservoirs that increase the risk of spread of new variants in humans.

[Hydrogen effect on the mechanisms of mucosal immunity in patients with COVID-19].

AIM: To study the inhalation of an active form of hydrogen effect to mucosal and system immunity in a rehabilitation program for health workers. MATERIALS AND METHODS: The study involved patients that survived COVID-19 after therapy with inhaled hydrogen for 90 minutes (n=30), and a control group of patients treated according to standard protocol for managing patients that survived COVID-19 during the rehabilitation period (n=30). Biomaterial was carried out in 2 stages: on the first day of the study, before the accepted therapy and on the 10th day of the study. The indicators of humoral and cellular immunity were studied. The levels of secretory immunoglobulin A (sIgA) and IgG were investigated using the method of enzyme-linked immunosorbent assay. Phagocytosis was assessed on a Beckman Coulter FC-500 flow cytometer. Statistical data processing was carried out in the GraphPad Prism 7.00 software using nonparametric methods. RESULTS: It was shown that the phagocytic index (PI) of monocytes in nasal scrapings after inhaled hydrogen treatment did not significantly change relative to the first day of treatment and control, while the PI of granulocytes in nasal scrapings significantly increased relative to the first day by 2.5 times (p=0.000189), as well as relative to the control by 1.1 times (p=0.047410). PI of monocytes in pharyngeal scrapings showed a significant increase relative to the first day of treatment by 2.8 times (p=0.041103), however, did not differ relative to the control. PI of granulocytes of pharyngeal scraping did not differ significantly relative to the first day and control. PI of granulocytes and blood monocytes of the studied group did not change significantly. PI of granulocytes and monocytes of peripheral blood relative to control during therapy did not change. The sIgA level in nasal scrapings significantly increased by 2.9 times, while in pharyngeal scrapings the level of sIgA significantly decreased by 2 times. Сonclusion. We have shown an increase in granulocytes PI in the nasal cavity and oral monocytes, as well as in the level of sIgA in the nasal cavity during therapy with active hydrogen. The data obtained indicate the effectiveness of therapy, which can be used both in the treatment of COVID-19, and in post-COVID syndrome as an additional therapy. The absence of changes in blood parameters, as well as individual links in nasal and pharyngeal scrapings, requires further study to develop ways to overcome treatment tolerance.

[The prospects for the use of drugs based on the phenomenon of RNA interference against HIV infection].

The human immunodeficiency virus (HIV) is currently one of the most pressing global health problems. Since its discovery in 1978, HIV has claimed the lives of more than 35 million people, and the number of people infected today reaches 37 million. In the absence of highly active antiretroviral therapy (HAART), HIV infection is characterized by a steady decrease in the number of CD4+ T-lymphocytes, but its manifestations can affect the central nervous, cardiovascular, digestive, endocrine and genitourinary systems. At the same time, complications induced by representatives of pathogenic and opportunistic microflora, which can lead to the development of bacterial, fungal and viral concomitant infections, are of particular danger. It should be borne in mind that an important problem is the emergence of viruses resistant to standard therapy, as well as the toxicity of the drugs themselves for the body. In the context of this review, of particular interest is the assessment of the prospects for the creation and clinical use of drugs based on small interfering RNAs aimed at suppressing the reproduction of HIV, taking into account the experience of similar studies conducted earlier. RNA interference is a cascade of regulatory reactions in eukaryotic cells, which results in the degradation of foreign messenger RNA. The development of drugs based on the mechanism of RNA interference will overcome the problem of viral resistance. Along with this, this technology makes it possible to quickly respond to outbreaks of new viral diseases.

Antimicrobial Activity of the Serum before and after Vaccination with EpiVacCorona.

We evaluated the effect of vaccination with anti-COVID-19 vaccine EpiVacCorona on serum antimicrobial activity, formation of specific IgG antibodies, and expression of some antimicrobial peptides. Antimicrobial activity of the serum from 55 volunteers towards S. aureus cells was measured spectrophotometrically; IgG-antibodies against SARS-CoV-2 antigen were assayed by ELISA; expression of genes encoding antimicrobial peptides LL37, HBD1, and HBD2 was evaluated by PCR with reverse transcription. Total antimicrobial serum activity and activity of its low-molecular-weight fraction containing antimicrobial peptides demonstrated an inverse correlation. Both activities after vaccination increased in case of low initial values, but decreased in case of high initial values. The vector of change of specific IgG antibodies to coronavirus inversely correlated with the vector of change of activity of antimicrobial peptide fraction. The expression of genes of antimicrobial peptides LL37, HBD1, and HBD2 looked like normal distribution depending on activities of the antimicrobial peptides in the corresponding sera.

Immunogenic properties of SARS-CoV-2 inactivated by ultraviolet light.

Vaccination against COVID-19 is the most effective method of controlling the spread of SARS-CoV-2 and reducing mortality from this disease. The development of vaccines with high protective activity against a wide range of SARS-CoV-2 antigenic variants remains relevant. In this regard, evaluation of the effectiveness of physical methods of virus inactivation, such as ultraviolet irradiation (UV) of the virus stock, remains relevant. This study demonstrates that the UV treatment of SARS-CoV-2 completely inactivates its infectivity while preserving its morphology, antigenic properties, and ability to induce the production of virus-neutralizing antibodies in mice through immunization. Thus, the UV inactivation of SARS-CoV-2 makes it possible to obtain viral material similar in its antigenic and immunogenic properties to the native antigen, which can be used both for the development of diagnostic test systems and for the development of an inactivated vaccine against COVID-19.

[Biological activity of interferons in the novel coronavirus infection COVID-19].

INTRODUCTION: The immunopathogenesis of the novel coronavirus infection COVID-19 is usually associated with the development of imbalance in the immune response to its causative agent, SARS-CoV-2 virus (Coronaviridae: Coronavirinae: Betacoronavirus: Sarbecovirus). This is manifested, in particular, by interferons' (IFNs) deficiency at the beginning of the disease followed by hyperproduction of pro-inflammatory cytokines. The virus causes a decrease in IFN types I (α/ß) and III (λ) levels; changes in IFN type II (γ) are less studied. In this regard, it is relevant to assess the functional bioactive IFN (interferon status) in COVID-19. The aim of the study was to assess the antiviral potential of the body by testing the biologically active IFNs in COVID-19. MATERIAL AND METHODS: We used biological serum samples of COVID-19 patients taken in the acute phase (110 patients on the 1-5 days of the disease) and during rehabilitation (47 patients during 1-3 months after the disease onset). Assessment of interferon status was performed according to the technique developed by the authors and described earlier. RESULTS: The IFN status of patients with COVID-19 in the acute period and in the phase of post-infection rehabilitation was studied вduring the observation period. It was found that SARS-CoV-2 causes a pronounced inhibition of biological activity of IFN types I and II compared to the reference values by more than 20 and 7 times, respectively. During the post-COVID period, incomplete recovery of the IFN system activity was registered, which proceeded very slowly. No cases of reaching physiological indicators of interferon status were identified during the observation period. CONCLUSION: The obtained data on deficiency of the functional biologically active IFN confirm the hypothesis about the predominant role of impaired IFN production of different types in the immunopathogenesis of the novel coronavirus infection.

[The assessment of a role of muramyl peptides in the treatment of patients with aggressive form of periodontitis]. / Izuchenie roli kompozitsii muramilpeptidov pri lechenii patsientov s agressivnoi formoi parodontita.

THE AIM OF THE STUDY: Was to determine the effect of the drug based on the composition of muramyl peptides isolated from the cell walls of gram-negative bacteria on the production of α-defensins and the detectability of Porphyromonas gingivalis in patients with an aggressive form of periodontitis. MATERIAL AND METHODS: 60 patients aged 28 to 40 years with an aggressive form of periodontitis were randomized into two equal groups, the main and control. In both groups, patients were removed dental deposits and taught the rules of oral hygiene, followed by three-fold control. In the main group, 200 micrograms of the drug based on the composition of muramyl peptides were additionally administered intramuscularly daily for 7 days. Initially and after 7, 21, 90 days, the level of human neutrophil peptides (hnp1-3) in blood serum and periodontal pockets was determined by the enzyme immunoassay, as well as the presence of P. gingivalis in periodontal pockets by polymerase chain reaction (PCR). RESULTS: In patients of the control group, the concentration of hnp1-3 in periodontal pockets and blood serum did not change significantly during the entire study. The use of PM in the main group caused an increase in the local and systemic levels of hnp1-3, which correlated with a persistent decrease in the detectability of P. gingivalis. CONCLUSION: The drug based on the composition of muramyl peptides of the cell wall of gram-negative bacteria potentiates the eradication of P. gingivalis by stimulating the production of hnp1-3 in patients with an aggressive form of periodontitis.

Potential of application of the RNA interference phenomenon in the treatment of new coronavirus infection COVID-19.

COVID-19 has killed more than 4 million people to date and is the most significant global health problem. The first recorded case of COVID-19 had been noted in Wuhan, China in December 2019, and already on March 11, 2020, World Health Organization declared a pandemic due to the rapid spread of this infection. In addition to the damage to the respiratory system, SARS-CoV-2 is capable of causing severe complications that can affect almost all organ systems. Due to the insufficient effectiveness of the COVID-19 therapy, there is an urgent need to develop effective specific medicines. Among the known approaches to the creation of antiviral drugs, a very promising direction is the development of drugs whose action is mediated by the mechanism of RNA interference (RNAi). A small interfering RNA (siRNA) molecule suppresses the expression of a target gene in this regulatory pathway. The phenomenon of RNAi makes it possible to quickly create a whole series of highly effective antiviral drugs, if the matrix RNA (mRNA) sequence of the target viral protein is known. This review examines the possibility of clinical application of siRNAs aimed at suppressing reproduction of the SARS-CoV-2, taking into account the experience of similar studies using SARS-CoV and MERS-CoV infection models. It is important to remember that the effectiveness of siRNA molecules targeting viral genes may decrease due to the formation of viral resistance. In this regard, the design of siRNAs targeting the cellular factors necessary for the reproduction of SARS-CoV-2 deserves special attention.

LC-MS/MS analysis of lesional and normally looking psoriatic skin reveals significant changes in protein metabolism and RNA processing.

BACKGROUND: Plaque psoriasis is a chronic autoimmune disorder characterized by the development of red scaly plaques. To date psoriasis lesional skin transcriptome has been extensively studied, whereas only few proteomic studies of psoriatic skin are available. AIM: The aim of this study was to compare protein expression patterns of lesional and normally looking skin of psoriasis patients with skin of the healthy volunteers, reveal differentially expressed proteins and identify changes in cell metabolism caused by the disease. METHODS: Skin samples of normally looking and lesional skin donated by psoriasis patients (n = 5) and samples of healthy skin donated by volunteers (n = 5) were analyzed by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After protein identification and data processing, the set of differentially expressed proteins was subjected to protein ontology analysis to characterize changes in biological processes, cell components and molecular functions in the patients' skin compared to skin of the healthy volunteers. The expression of selected differentially expressed proteins was validated by ELISA and immunohistochemistry. RESULTS: The performed analysis identified 405 and 59 differentially expressed proteins in lesional and normally looking psoriatic skin compared to healthy control. In normally looking skin of the patients, we discovered decreased expression of KNG1, APOE, HRG, THBS1 and PLG. Presumably, these changes were needed to protect the epidermis from spontaneous activation of kallikrein-kinin system and delay the following development of inflammatory response. In lesional skin, we identified several large groups of proteins with coordinated expression. Mainly, these proteins were involved in different aspects of protein and RNA metabolism, namely ATP synthesis and consumption; intracellular trafficking of membrane-bound vesicles, pre-RNA processing, translation, chaperoning and degradation in proteasomes/immunoproteasomes. CONCLUSION: Our findings explain the molecular basis of metabolic changes caused by disease in skin lesions, such as faster cell turnover and higher metabolic rate. They also indicate on downregulation of kallikrein-kinin system in normally looking skin of the patients that would be needed to delay exacerbation of the disease. Data are available via ProteomeXchange with identifier PXD021673.

Effect of Albumin on Tumor Cells In Vitro.

The study examined the effect of BSA on cultured cells of breast cancer, erythroleukemia, and ovarian carcinoma. BSA cytotoxic activity was examined with light microscopy and spectrophotometry in the concentration range of 6.25 to 50 mg/ml. The high concentrations of BSA disrupted the tumor cells in parallel with formation of vesicular debris. The destruction parameters were similar in diverse types of cells: BSA (50 mg/ml) disrupted 75.5±0.7% breast cancer cells, 75.8±0.2% erythroleukemia cells, and 78.8±0.1% cells of ovarian carcinoma (p≥0.05). The effect of BSA was dose-dependent in each type of cells. The data attest that BSA can disrupt various tumor cells in vitro.

Proliferative Activity of Mouse Splenocytes in Physiological Pregnancy and in Models of Spontaneous and Muramylpeptide-Dependent Abortions.

Spontaneous proliferative activity of splenocytes in female CBA mice and the response of these cells to antigens of allogeneic male BALB/c and DBA/2 mice in a mixed splenocyte culture were evaluated by 3H-thymidine incorporation in different pregnancy models. ♀CBA×♂BALB/c mating was used for modeling physiological pregnancy. Spontaneous abortions were reproduced by abortion-prone ♀CBA×♂DBA/2 mating. In order to simulate immunostimulant-induced and immunostimulant-potentiated abortions, 0.83 mg/kg muramyl dipeptide ß-heptylglycoside was intraperitoneally injected to CBA females mated with BALB/c or DBA/2 males, respectively, on gestation days 5 and 7. The increase in the rate of embryo resorption in the models of spontaneous, induced, and potentiated abortions occurred against the background of an increase in the level of spontaneous proliferation of splenocytes and a decrease in their reactivity to paternal antigens on gestation day 9.

Unfavorable Humoral Factors for Spermatozoon Survival in Vaginal Medium.

The effects of vaginal secretion, its antibacterial peptide fraction, albumin, and bacterial metabolites on the spermatozoon membranes were studied. Vaginal secretion was collected from healthy women; the fraction of antibacterial peptides was isolated with the use of membrane filter; electrophoretically pure BSA served as albumin; bacterial metabolites were isolated from supernatants of cultured Candida albicans yeast and E. coli and Staphylococcus aureus bacteria. Antibacterial activities of the preparations were evaluated by spectrophotometry and microscopy. Albumin in a concentration close to its serum concentration (50 mg/ml) destroyed spermatozoon membranes by 83.8±2.7% with the formation of vesicular debris. The native vaginal secretion and its antibacterial peptide fraction also destroyed spermatozoa by 50.8±4.4 and 18.0±9.7%, respectively. Activities of bacterial metabolites in concentrations close to the natural did not surpass 3%.

[The potential of synthetic small interfering RNA-based antiviral drugs for influenza treatment].

Influenza is a worldwide public health problem. Annually, this infection affects up to 15% of the world population; and about half a million people die from this disease every year. Moreover, influenza A and B viruses tend to garner most of the attention, as these types are a major cause of the epidemics and pandemics. Although the influenza virus primarily affects the respiratory tract, it may also affect the cardiovascular and central nervous systems. Several antiviral drugs, that target various stages of viral reproduction, have been considered effective for the treatment and prevention of influenza, but some virus strains become resistant to these medications. Thus, new strategies and techniques should be developed to overcome the antiviral drug resistance. Recent studies suggest that new drugs based on RNA interference (RNAi) appear to be a promising therapeutic approach that regulates the activity of viral or cellular genes. As it is known, the RNAi is a eukaryotic gene regulatory mechanism that can be triggered by a foreign double-stranded RNA (dsRNA) and results in the cleavage of the target messenger RNA (mRNA). This review discusses the prospects, advantages, and disadvantages of using RNAi in carrying out a specific treatment for influenza infection. However, some viruses confer resistance to small interfering RNAs (siRNA) targeting viral genes. This problem can significantly reduce the effectiveness of RNAi. Therefore, applying siRNAs targeting host cell factors required for influenza virus reproduction can be a way to overcome the antiviral drug resistance.

Polymorphism of the IL-1ß, TNF, IL-1RA and IL-4 Cytokine Genes Significantly Increases the Risk of Preterm Birth.

Preterm birth is not only medical, but also a social problem. The global goal of medicine is prevention of preterm labor and identification of risk factors leading to preterm birth. The objective of our study was to find the association between polymorphic markers in the cytokine IL-1ß, TNF-α, IL-1Ra, and IL-4 genes and development of preterm labor. The prospective study was conducted in 108 pregnant women with the risk of preterm birth. The main group consisted of 66 women whose pregnancy ended with preterm delivery despite the ongoing therapy. The comparison group included 42 women with the full-term delivery. The dominant T allele of the cytokine IL-1ß gene polymorphism rs1143634 (3953C→T) was 7.6 times more common in women with preterm delivery vs. the comparison group (36.4 and 4.8%, respectively; RR, 1.802; 95% CI, 1.420-2.288; p < 0.05); its homozygous form was detected only in women with preterm delivery at the very early gestation age (less than 26 weeks). The dominant proinflammatory allele 2R of the IL-1 receptor antagonist gene (IL-1Ra) was 1.5 times more common in women with preterm delivery than in the comparison group (63.6 and 42.8%, respectively; RR, 1.400; 95% CI, 1.009-1.943; p < 0.05), which makes the 2R allele the risk factor for preterm birth. The 2R/2R and 2R/4R genotypes led to a very early and early preterm delivery, respectively. The combination of three or four proinflammatory genotypes was detected only in women with a very early preterm delivery, which confirms that the combination of several proinflammatory genotypes is an extremely unfavorable factor for the full-term pregnancy. Identification of genetic polymorphisms in the interleukin genes at the periconceptional stage will help to prevent the risk of preterm delivery, which will reduce the incidence of preterm births, as well as perinatal morbidity and mortality.

Antimicrobial Effect of Albumin on Bacteria and Yeast Cells.

We studied the effect of albumin (human serum, bovine serum, and ovalbumin) on Candida albicans, Cryptococcus neoformans, E. coli, and Staphylococcus aureus cells. Antimicrobial activity was evaluated by microscopy, inoculation, and spectrophotometry. All three albumins showed antimicrobial activity against all studied cultures and their effect was dose-dependent. At concentrations of serum albumins close to physiological (50 mg/ml), the cells of microorganisms were destroyed with the formation of debris vesicles, while at lower concentrations (10 mg/ml), only cell membrane integrity was impaired. According to spectrophotometry, activity of the human serum albumin in a physiological concentration against the studied microorganisms was close to the activity of native human serum.

The role of regulatory RNAs (miRNAs) in asthma.

INTRODUCTION: Recently, a great deal of attention has been paid to the investigation of regulatory functions of microRNA. Currently, many different mechanisms involved in the pathogenesis of asthma are known, but the whole picture of pathogenesis has not yet been studied. CONCLUSIONS: MicroRNAs play an important role in the regulation of many cellular processes. Undoubtedly, these regulatory molecules are involved in the pathogenesis of asthma, and therefore can be potential targets for treatment.

[Study of heat shock protein gene 70 (HSP70) expression and its polymorphous marker (+ 1267A> G) in women under exposure to a long-term stress.]

There was studied the HSP70 gene and its polymorphic marker + 1267A> G (rs754888705) in the HSP70 gene expression in32 women under long-term stress, which was caused by inpatient treatment of their oncologic child. A control group included 25 women without long-term stress factors. There was studied a correlation between the expression level of the HSP70 gene in women and their high blood pressure (BP) episodes. The average duration of stress in the group of children's mothers was 7.3 (2.5-11.5) months. Anxiety level according to HADS in the main group was significantly increased and amounted to 8.7 (7-10) points, in the control group 5 (2-7) points. Depression level in the main group was significantly higher and amounted to 7.7 (7-9) points, in the control group 3.3 (1-5) points. Comparison of the HSP70 gene expression level in blood of young women of the main study group with expression level of this gene in the control group showed a statistically significant predominance of HSP70 gene expression in the main group. The episodes of high BP in women who were under stress conditions did not influence the expression level of the HSP70 gene. Analysis of the alleles of the polymorphic marker frequency in the gene HSP70-2 1267A> G (rs754888705) in the main and control groups showed a statistically significant predominance of allele A in the group of mothers under stress, and predominance of the allele G in the control group. Comparative analysis of the polymorphic marker genotype frequencies in the gene HSP70-2 1267A> G (rs754888705) showed that the AA genotype is significantly more frequent in mothers with episodes of BP increase compared to women without it. An increased level of the HSP70 gene expression in peripheral blood leukocytes in mothers with a life-threatening disease of their child indicates the damaging effect of long-lasting psychoemotional stress at the cellular level and activation of the protective reaction mediated by HSP70. Studying of the genotype AA characteristics of the polymorphic marker A1267G (rs754888705) of the HSP70-2 gene in women under long-lasting stress will let us evaluate the role of genetic factors in hypertensive reactions development.

[The expression of TLR4 and HBD3 in epithelial cells of oral mucosa by surgical treatment of periodontitis]. / Ekspressiya genov TLR4 i HBD-3 v epitelial'nykh kletkakh slizistoi obolochki pri khirurgicheskom lechenii parodontita.

The expression of TLR4 and HBD3 in epithelial cells of the oral cavity was studied using polymerase chain reaction in real-time in patients with inflammatory and destructive periodontal lesions before and after surgery using osteoplastic material. Analysis of TLR4 and HBD3 expression in epithelial cells demonstrates the key role of the innate immune factors in the pathogenesis of inflammatory and destructive periodontal lesions. TLR4 gene expression was increased 1.5-7.0 times and HBD3 1.5-5.0 times compared to healthy individuals. Surgical treatment resulted in an effective rehabilitation and normalization of innate immunity.

[MECHANISMS OF ATTENUATION OF COLD-ADAPTED STRAIN A/KRASNO- DAR/101/35/59 (H2N2)].

AIM: Study of mechanisms of attenuation of cold-adapted (ca) influenza virus strain A/ Krasnodar/101/35/59 (H2N2), associated with disruption of NS1 protein functions. MATERIALS AND METHODS: Study of interferonogenic activity of ca strain A/Krasnodar/101/35/59 (H2N2), its parent variant A/Krasnodar/101/59 (H2N2), virulent strain A/WSN/33 (H1N1) and a number of single gene and multiple gene reassortants between these strains, obtained using reverse genetics, was carried out. Study of dynamics of IFNß gene expression was carried out by using a methodical approach of RT-PCR in real time mode. RESULTS: Inclusion of PB-1 gene of ca strain A/ Krasnodar/101/35/59 (H2N2) with reversion to wild type into genome composition of virulent strain A/WSN/33 (H1N1) does not result in a sharp change of interferonogenic activity of the reassortant. At the same time, similar inclusion of PB-1 gene of ca strain resulted in an incredible growth of interferonogenic activity of the reassortant. On the other hand, inclusion of NP-gene of wild type strain A/Krasnodar/101/59 (H2N2) into genome composition of the wild type strain A/WSN/33 did not differ by effect on interferonogenicity of the reassortant from inclusion of NP-gene of ca strain. CONCLUSION: Both constellations of genes of parent variants and mutations localized in these genes could affect formation of attenuation phenotype of reassortants. The data obtained allow to assume possible mechanisms of attenuation of ca strains, associated with disruption.of NS gene function.