The emergence of new influenza virus strains presents a continuous challenge for global public health. mRNA technology offers a promising platform for rapidly developing therapeutics, particularly monoclonal antibodies, that can protect against viral infections. In this study, we engineered mRNA constructs encoding two types of antibodies: secreted antibodies specific to the hemagglutinin of the influenza A virus, based on previously characterized Fi6 antibodies, and intracellular Fab fragments targeting the nucleoprotein of the influenza B virus, derived from the 2/3 antibodies. The administration of mRNA constructs in vitro resulted in the successful synthesis of functional antibodies, which exhibited antiviral activity against influenza viruses. This study confirms the feasibility of using mRNA technology to develop therapeutic antibodies against influenza virus infections. The findings pave the way for future clinical applications of mRNA-based therapeutics, enhancing preparedness for emerging viral threats.

The in vitro transcription reaction (IVT) is an important step in the production of synthetic mRNAs. Optimizing the reaction conditions of the IVT and using its own reactants will minimize the reaction time and costs at maximum yield. We synthesized mRNAs using original T7-Pol and PAP enzymes, performed translation, transfection, and fluorescence intensity analyses of the obtained samples versus control commercial mRNAs.

Influenza poses a significant public health concern, and the development of therapeutic antibodies provides a promising avenue for its treatment. In this study, we generated mRNA sequences encoding neutralizing antibodies targeting the hemagglutinin of influenza A virus, as well as antibodies specific to the nucleoprotein of influenza B virus. We successfully demonstrated the antiviral activity of mRNA-encoded antibodies targeting the hemagglutinin against influenza A virus in vitro.

RNA-based vaccines are the newest promising alternative to traditional approaches to treat viral diseases. In this study, we obtained mRNA encoding the hemagglutinin of influenza A subtype H7N9 by in vitro transcription and evaluated the efficiency of its translation on the A549 cell line. It was shown that mRNA is efficiently delivered and translated in vitro and can be successfully used for further experiments in vivo.

Objective: to analyze the epidemiological and clinical features of acute respiratory infections occurring during the St. Petersburg 2017–2018 and 2018–2019 epidemic seasons.Materials and methods: the study included 457 patients, treated in St. Petersburg clinics from 2017–2019, displaying symptoms of acute respiratory infection (ARI), including evaluation of their clinical histories. Pathogen types were determined by polymerase chain reaction (PCR). Data analysis was carried out using mathematical statistics methods using the Statistica 10 software package (StatSoft Inc.).Results: in this study, we examined the epidemiological and clinical features of acute respiratory infections in St. Petersburg occurring during two epidemic seasons, 2017–2018 and 2018–2019. The 2017–2018 season was characterized by a prevalence of infections caused by influenza B viruses and influenza A subtype H3N2 viruses. In the 2018–2019 season, there was a greater number of acute respiratory viral infections (ARVIs) and infections caused by influenza A subtype H1N1pdm; influenza B virus was detected only in isolated cases. In the 2017–2018 sore throats and muscle aches were a characteristic symptom of influenza A H1N1pdm infections, of bacterial infections – only sore throats. It was shown that throat pain and vasodilation of the scleral and soft palate vessels were significantly more frequent in the 2017–2018 season, compared to the 2018–2019 season. Cough and redness of the posterior pharyngeal wall were hallmark signs of ARVIs in the 2018–2019 season.Conclusion: according to the data, each epidemic season is characterized not only by its own type-specific acute respiratory infection frequencies, but also by different clinical manifestation frequencies. For global monitoring, treatment effectiveness evaluation, and refined study of acute respiratory infection clinical features, it is advisable to use approaches which incorporate accurate, specific, and rapid molecular biological methods capable of identifying a broad range of pathogens.

The aim of this investigation was a comparative analysis of isotypic structure of specific antiviral systemic humoral immune response in hospitalized patients with influenza caused by virus A(H3N2) or A(H1N1), including the A(H1N1)pdm09. Paired acute and convalescent phase sera from 109 adult patients aged 18 to 67 years with laboratoryconfirmed influenza A were analyzed by ELISA. Purified surface glycoproteins of influenza A viruses of different subtypes containing the hemagglutinin and neuraminidase were used as antigen for sensitization of plates in ELISA.The absence of type-specific conserved internal proteins in antigenic material allowed to carry out a subtype-specific differentiation of antibodies against influenza viruses in ELISA. Regardless of the subtype of influenza A viruses caused the disease, the most pronounced response was observed by subtype-specific IgG1 (70–90% of seroconversions). It has been shown for the first time that low activity of virus-induced IgG2 (6–9% of seroconversions) is a peculiarity of the immune response both to primary or recurrent infections with A(H1N1)pdm09. In patients repeatedly suffered by «seasonal» influenza A(H1N1) in 2007/2008 or influenza A(H3N2) in 2012–2014 IgG2 seroconversion’s rates were 40–59% (р < 0,05). Reaction virusspecific IgG3 was also weaker in patients with influenza A(H1N1)pdm09 (29–44% of seroconversions) than in subjects with influenza A(H1N1) or A(H3N2) (65% and 56% of seroconversions, respectively). Geometric mean titers of virus neutralizing antibodies identified during recovery phase in patients with primary and secondary influenza A(H1N1)pdm09 (1/28 and 1/103, respectively) were significantly lower than in patients recovered from influenza A(H1N1) or A(H3N2) (GMT were 1/594 and 1/378, respectively). It was shown that the surface glycoproteins of influenza A viruses may be an allergens. Virus-specific IgE seroconversion rates were comparable in all groups reaching 25–45%. The high activity of virus-induced serum IgA was detected in patients with influenza A(H3N2) or A(H1N1)pdm09 (60–79% of seroconversions). Thus, study of virus-specific activity of various immunoglobulin isotypes provides important information about the formation of adaptive antiviral immune response to influenza A viruses, and also estimate the contribution of its protective and immunopathogenic components to pathogenesis of the disease.

The aim of this investigation was a comparative analysis of isotypic structure of specific antiviral systemic humoral immune response in hospitalized patients with influenza caused by virus A(H3N2) or A(H1N1), including the A(H1N1)pdm09. Paired acute and convalescent phase sera from 109 adult patients aged 18 to 67 years with laboratoryconfirmed influenza A were analyzed by ELISA. Purified surface glycoproteins of influenza A viruses of different subtypes containing the hemagglutinin and neuraminidase were used as antigen for sensitization of plates in ELISA.The absence of type-specific conserved internal proteins in antigenic material allowed to carry out a subtype-specific differentiation of antibodies against influenza viruses in ELISA. Regardless of the subtype of influenza A viruses caused the disease, the most pronounced response was observed by subtype-specific IgG1 (70–90% of seroconversions). It has been shown for the first time that low activity of virus-induced IgG2 (6–9% of seroconversions) is a peculiarity of the immune response both to primary or recurrent infections with A(H1N1)pdm09. In patients repeatedly suffered by «seasonal» influenza A(H1N1) in 2007/2008 or influenza A(H3N2) in 2012–2014 IgG2 seroconversion’s rates were 40–59% (р < 0,05). Reaction virusspecific IgG3 was also weaker in patients with influenza A(H1N1)pdm09 (29–44% of seroconversions) than in subjects with influenza A(H1N1) or A(H3N2) (65% and 56% of seroconversions, respectively). Geometric mean titers of virus neutralizing antibodies identified during recovery phase in patients with primary and secondary influenza A(H1N1)pdm09 (1/28 and 1/103, respectively) were significantly lower than in patients recovered from influenza A(H1N1) or A(H3N2) (GMT were 1/594 and 1/378, respectively). It was shown that the surface glycoproteins of influenza A viruses may be an allergens. Virus-specific IgE seroconversion rates were comparable in all groups reaching 25–45%. The high activity of virus-induced serum IgA was detected in patients with influenza A(H3N2) or A(H1N1)pdm09 (60–79% of seroconversions). Thus, study of virus-specific activity of various immunoglobulin isotypes provides important information about the formation of adaptive antiviral immune response to influenza A viruses, and also estimate the contribution of its protective and immunopathogenic components to pathogenesis of the disease.

AIM:To estimate the r, virological and clinical characteristics of chronic viral hepatitis (CVH) with double B/C infection.MATERIALS AND METHODS:We examined 282 patients with CVH. Genomes of hepatitis B virus (HBV) and hepatitis C virus (HCV) were studied by PCR in blood and liver (AmpliSens HBV and Amplisens HCV Russia), nuclear proteins (HBcorAg HBV and NS3 HCV) were determined by immunohistochemical method (Novocastra, UK), HBVgenome was sequenced by the Sanger method using ABI prism BigDye Terminator v3.1 kits and ABIPRISM 3100 analyzer (AppliedBiosystems, USA). Indices of histological activity (HAI), fibrosis, and portal vein (PV) congestion index (CI) were calculated by formula CI=SBB/LB V where S is P V cross section area in cm2 and LB V - linear blood flow velocity in cm/s (Vivid Pro- 7 apparatus, USA).RESULTS:CVH with double B/C infection was diagnosed in 85 (30.1%) patients including 44.7% with viral genomes and proteins in the live; 42.4% with HCVviremia, and 12.9% with HBJV/HCVviremia. Maximum CVH activity was documented in patients with latent HBV/HCVviremia (ALT 157.2±59.2 U/, HAI 11.6±1.3,fibrosis 2.8±0.7, C1 0.059±0.005); it was minimal inpatients.without viremia (Alt 76.25±63.0 U/I, HAI 6.7+-0.6,fibrosis 1.7±0.5, CI 0.042±0.001;p <0.05). Patients with latent HBV infection had precore/ore and pres/s mutations in HBVgenome and cytoplasmic localization ofHBcorAg.CONCLUSION:Double B/C infection was diagnosed in 30.1% of the patients with CVH dominated by HCV Patients with latent HBVhadprecore/ore and pres/s mutations. The highest intensity of hepatic cellular inflamation,fibrosis, and PV congestion was associated with HBV/HCV viremia and the lowest with intrahepatic localization of both viruses.

Introduction. Biological properties of virus, such as susceptibility to antivirals, the clinical course of chronic hepatitis B (CHB), the probability of developing cirrhosis and hepatocellular carcinoma are determined by genotype and mutations in the genome of the hepatitis B virus (HBV).The aim of the study was evaluating of HBV genetic variants in patients with CHB from St. Petersburg hospitals.Material and methods. A total of 1414 CHB patients with positive polymerase chain reaction HBV genome in blood and/or liver tissue were observed. Genotype was determined in 298 patients, sequencing of the polymerase gene fragment was performed in 80 patients.Results. Viral DNA was detected in 323 (55.8%) patients with CHB. Genotype D was determined in 238 (80,1%), genotype A – in 49 (16,5%), C genotype – in 2 (0,7%) and mixed A+D – in 8 (2,7%) patients. Substitutions in YMDD-motif of the polymerase protein (M204I/V) as well as other primary and secondary resistance mutations to nucleotide analogues (lamivudine, telbivudine, entecavir) were found in four patients. Mutations in the reverse transcriptase (rt) region of polymerase gene were shown to affect the structure of surface protein. The substitution rtA181T in three patients resulted in formation of stop codon (sW172*) and premature termination of surface protein synthesis. The absence of HBeAg and the degree of fibrosis increase in 7 patients may be the result of mutations identified in core gene (G1896A, A1762T, G1764A).Conclusion. Study of the geographical distribution of HBV genotypes and identification of amino acid substitutions leading to decrease in serum markers concentration and emergence of resistance antivirals mutations is of great practical importance for predicting severity of the disease and effectiveness of antiviral therapy.

Аnalogues of nucleos(t)ides (AN) such as lamivudine (LAM), telbivudine (TBV), adefovir (ADP), entecavir (ENT) are widely used for the treatment of chronic hepatitis B (CHB). However, the prolonged treatment using these drugs often leads to the development of drug resistance. The most common substitutions in the reverse transcriptase are methionine for valine (rtM204V), or methionine for isoleucine (rtM204I) at position 204. Early AN-resistant mutations detection is of great importance to determine the treatment strategy of patients with CHB. Currently there are many highly sensitive methods for detection of drug resistance mutations, such as next-generation sequencing, reverse hybridizationbased line probe assay (LiPA), mass spectrometry. However, these methods require expensive equipment and reagents, and they are not widely used in clinical laboratories. The aim of this study was to develop a simple and accurate real-time PCR method for detection of rtM204I/V mutation. This method showed high specificity and sensitivity (1000 copies/ml), it is less laborious and does not require additional equipment, fast and cost effective compared to other methods. HBV mutations of resistance to AN were determined in 5 groups of patients with CHB. Patients of the first group received monotherapy with pegylated interferon (n = 12), the second group — lamivudine (n = 10), the third group — telbivudine (n = 7), the fourth group — entecavir (n = 15). The fifth group consisted of patients who did not receive antiviral therapy (n = 3). The frequency of mutations in HBV polymerase YMDD-motif was determined among 47 patients with CHB: it was 10% for lamivudine treated patients, 20% — for entecavir, 28% — for telbivudine. YIDD/YVDD motifs were identified in two patients and YMDD/YIDD — in one patient. Real-time PCR method for the detection of AN-resistant rtM204I/V mutations in HBV polymerase can be used in routine diagnostics for primary screening of patients not responding to AN treatment. The application of this method can reduce the number of samples for in-depth study of primary and compensatory mutations of resistance to AN by sequencing method. The developed method versus Sanger-sequencing is fast, economical, and provides the detection of minor variants of HBV populations.

The results of molecular genetic analysis of more than 280 strains of influenza A virus subtypes H1N1 and H3N2 circulating in Russia in 2006-2012 are presented. The genetic changes underlying the evolution of the virus strains and sensitivity to antiviral drugs were analyzed. Significant changes in the genetic structure of influenza A viruses circulating in the Russian Federation and their phylogenetic affiliation are shown to occur within the studied period. The studies identifying codons under the positive selection in silico in the genes encoding surface proteins of the influenza virus were demonstrated to be efficient for the analysis of the antigenic drift and direction of evolutionary variability of the influenza viruses.

The results of molecular genetic analysis of more than 280 strains of influenza A virus subtypes H1N1 and H3N2 circulating in Russia in 2006-2012 are presented. The genetic changes underlying the evolution of the virus strains and sensitivity to antiviral drugs were analyzed. Significant changes in the genetic structure of influenza A viruses circulating in the Russian Federation and their phylogenetic affiliation are shown to occur within the studied period. The studies identifying codons under the positive selection in silico in the genes encoding surface proteins of the influenza virus were demonstrated to be efficient for the analysis of the antigenic drift and direction of evolutionary variability of the influenza viruses.

The analysis of 1558 clinical samples revealed influenza virus A(H1N1v) RNA in 339 patients with influenza and 163 fatal cases,which was made in May to December 2009. Data on the antigenic properties of more than 250 of pandemic virus strains isolated at the Research Institute of Influenza and the molecular genetic characteristics of 31 strains are presented. All the test isolates were found to have the S203 substitution in hemagglutinin, which was characteristic of one of 5 minor genome A(H1N1v) virus variants found in the United States and Mexico in 2009. All the test strains contain the S31N substitution in the M2 protein, which determines viral resistance to adamantine, and have no H275Y substitution in neuraminidase, which determines oseltamivir resistance. The substitution of amino acid residue of Asp to Gly at position 222 of HA was found in 8 (73%) of 11 isolates from postmortem lung and trachea samples and in 2 (10%) of 20 isolates from nasopharyngeal swabs. The determination of the pathogenic role of this substitution calls for further investigations.

Microarray technology is one of the most challenging methods of influenza A virus subtyping, which is based on the antigenic properties of viral surface glycoproteins – hemagglutinin and neuraminidase. On the example of biochip for detection of influenza A/H5N1 virus we showed the possibility of using multisegment RTPCR method for amplification of fluorescently labeled cDNA of all possible influenza A virus subtypes with a single pair of primers in influenza diagnostic microarrays.