[Peculiarities of the influenza and ARVI viruses circulation during epidemic season 2019-2020 in some regions of Russia].

INTRODUCTION: The surveillance of influenza viruses in ARVI structure and study of their properties in epidemic season 2019-2020 in Russian Federation are actual for investigations due to tasks of Global Influenza Strategy initiated by WHO in 2019. MATERIAL AND METHODS: The data of epidemiological surveillance on influenza- and ARVI-associated morbidity and hospitalization in different age groups of population were analyzed; virological, genetic and statistical methods were used. RESULTS: Preschool children were involved in epidemic the most. Meanwhile, the highest rate of hospitalization was observed in patients of 18-40 years old. Influenza A(H1N1)pdm09 virus dominated in etiology of ARVI in hospitalized patients and pneumonia. The role of respiratory viruses in severe cases of pneumonia and bronchoalveolar syndrome in children was shown. The differences in spectrum of circulating viruses caused ARVI in different regions of Russia were found. Influenza A(H1N1)pdm09 and B/Victoria-like viruses were the main etiological agents that caused of epidemic; its activity among all ARVI was 7.3 and 8.0%, respectively. The differences in antigenic properties of influenza A(H3N2) and B epidemic strains compared to vaccine viruses were found. The populations of epidemic strains were presented by following dominant genetic groups: 6B1.A5/183P for A(H1N1)pdm09, 3С.2а1b+137F for A(H3N2) and V1A.3 line B/Victoria-like for B viruses. The good profile of epidemic strains susceptibility to anti-neuraminidase inhibitors has been saved. The most of the studied influenza strains had the receptor specificity characteristic of human influenza viruses. CONCLUSIONS: Obtained results identified the peculiarities of viruses caused the influenza and ARVI in epidemic season 2019-2020 in different regions of Russia. These results suggested the important role of influenza A(H1N1) pdm09 in severe cases and pneumonia in adults 18-40 years old. The continuing drift in influenza viruses was found, which, apparently, could not but affect the efficacy of vaccine prophylaxis and was also considered in the recommendations of WHO experts on the composition of influenza vaccines for the countries of the Northern Hemisphere in the 2020-2021 season.

DRIFT OF INFLUENA A(H3N2) VIRUS: BIOLOGICAL, ANTIGENIC AND GENETIC PROPERTIES IN EPIDEMIC SEASON 2016-2017 IN RUSSIA AND COUNTRIES OF THE NOTHERN HEMYSPHERE.

The article presents the features of the influenza virus circulation for the period from October 2016 to May 2017 in some territories of Russia collaborating with the D.I. Ivanovsky Institute of Virology, Federal State Budgetary Institution "N.F. Gamaleya Federal Research Centre for Epidemiology and Microbiology", Ministry of Health of the Russian Federation. One of the 2016-2017 season's peculiarities in Russia and countries of the Northern hemisphere was the earlier start of an increase in ARD morbidity with peak indexes reached towards the end of December 2016 - January 2017. First, influenza A(H3N2) virus was predominant; then, it was followed by influenza B virus activity observed until the end of the season. The indexes of morbidity were higher than in the previous season, while the rates of hospitalization and mortality were lower, lethal cases being detected in persons 65 years old and older. Epidemic strains of influenza A(H3N2) virus belonged to 3c.2a genetic group, reference strain A/Hong Hong/4408/2014, and its subgroup 3c.2a1, reference A/Bolzano/7/2016, that are antigenically similar. Strains of influenza B virus were antigenically similar to the B/Brisbane/60/2008 vaccine virus. Strains were sensitive to oseltamivir and zanamivir. The share participation of non-influenza ARI viruses was similar to preliminary epidemic seasons. WHO has issued recommendations for influenza virus vaccines composition for 2017-2018 for the Northern hemisphere.

[The peculiarities of the influenza epidemics in some areas of Russia during 2012-2013 season. The influenza A (H1N1) pdm09 virus domination in European countries].

The peculiarities of the influenza viruses circulation in 2012-2013 are discussed. The results were obtained in 10 cities of Russia, where basic laboratories of the Influenza Ecology and Epidemics Center of on the basis of Ivanovsky Institute of Virology, Ministry of Health of the Russian Federation, are situated. The increasing rate of the ARD morbidity caused by influenza viruses was observed in January-March 2013. The highest indices of the morbidity were detected during 6-7 weeks with the following decreasing rate till threshold levels to week 14. The influenza A (H1N1) pdm09, A (H3N2), and B viruses were the cause of the epidemic, but their activity differed over areas of Russia. The results of study of the antigenic and genetic properties of the influenza strains demonstrated closed relatives with respect to vaccine strains. In addition, some heterogeneity of the circulating strains and their drift variants were found as well. All tested strains were sensitive to oseltamivir (excluding one A (H1N1) pdm09 strain), zanamivir, arbidol, and remained resistant to rimantadine. The ratio of the ARD viruses was comparable with the last epidemic seasons.

[Efficiency of the influenza A and B viruses isolation from nasopharyngeal swabs taken in the test tubes Sigma-Virocult (M40 Compliant, Sigma Virocult) and Virocult (M40 Compliant, Virocult) in 2010-2011 epidemic season].

The goal of this work was to compare the efficiency of the influenza A and B viruses Isolated during 2010-2011 epidemic season. The clinical samples were taken in the test tubes with the transport medium on the.basis of the medium EMEM and commercial test tubes Sigma-Virocult (M40 Compliant, Sigma Virocult) and Virocult (M40 Compliant, Virocult). The results of this work demonstrated higher efficiency of influenza A and B viruses isolation from nasopharyngeal swabs of the patients taken in the test tubes Sigma-Virocult (M40 Compliant, Sigma Virocult) and Virocult (M40 Compliant, Virocult) with the transport medium as compared with the efficiency of influenza strains isolation from nasopharyngeal swabs taken in test tubes with the medium EMEM with respect to all estimated indicators: efficiency of isolation, a passage of isolation and the titer of isolates. The possibility of the long-term storage of a clinical material at room temperature and at 4 degrees C was confirmed, without resorting to freezing, which is significant in the absence of the necessary equipment.

[Efficacy of anti-neuraminidase drugs application during and after an influenza pandemic].

The emergent 2009 A(H1N1) pandemic brought into acute focus the problem of choosing the most effective anti-influenza drugs for successive influenza infection spreading control. Oseltamivir and zanamivir, influenza virus neuraminidase inhibitors (NAIs), were recommended by the WHO experts for the treatment and prevention of influenza, including that caused by pandemic strains. A major concern regarding the use of specific antiviral compounds is the emergence of the drug-resistant strains. Oseltamivir carboxylate and zanamivir IC50 values were equal to 0.3-5.2 microM for the most of A(H1N1)pdm09 pandemic strains and 1.6-8.6 microM for the strains of influenza B virus in cell-based ELISA assay (2009-2010 season). All the studied strains of influenza A(H1N1 ) pdm09 (151) and B (22) viruses were sensitive to NAIs (2009-2011 seasons). For the first time in Russia oseltamivir-resistant A(H1N1) pdm09 influenza virus was isolated from the patient on the 5th day of a treatment course of this drug.

[Development of the influenza epidemic in season 2011-2012 in some areas of Russia: results of activity of the Influenza Etiology and Epidemiology Center of the Ivanovsky Institute of Virology].

The results of analysis of the peculiarities of the epidemic 2011-2012 development in the areas of 10 cities of Russia obtained by basic laboratories of IEES on the base of D.I. Ivanovsky Research Institute of Virology, Ministry of Public Health and Social Development of Russia, are presented. The increasing ARD morbidity caused by the influenza viruses was detected rather late--in February-March 2012. The highest indices of the morbidity were detected during weeks 10-13 followed by decreasing to threshold levels by week 27. Children 0-2 and 3-6 years old were involved the most, meantime the high rate of hospitalization was found for 15-64 years old aged group (25%). Influenza A(H3N2) and B viruses were the cause of the epidemic. The results of studies of the antigenic and genetic properties of the influenza strains showed most of them to be close relatives to the vaccine strains. Some heterogeneity of circulating strains and their drift variants were found as well. All tested strains were sensitive to arbidol, oseltamivir and zanamivir, and saved resistance to rimantadine. The ratio of ARD viruses was comparable with the last epidemic seasons.