Circulation of Highly Pathogenic Avian Flu Virus in the Russian Federation in 2014-2015

Given are the data on the circulation of highly pathogenic flu virus, A/H5, within the last two years. Discussed is the current state of the situation on H5 flu in the territory of the Russian Federation, where during 2014-2015, for the first time since 2010, registered has been the isolation of highly pathogenic flu virus, H5N1 and H5N8 subtypes. It is demonstrated that the territory of Russia plays a significant role in trans-continental transfer of flu viruses by wild birds from South-Eastern Asia into Europe and North America. Moreover, an assumption is made that a continued circulation of highly pathogenic viruses in the territory of the country is quiet possible

Overview of the Situation on Highly Pathogenic Avian Influenza Virus H5 in Russia in 2016–2017

In 2016–2017, several outbreaks among wild and domestic birds caused by highly pathogenic influenza virus were recorded in the territory of the Russian Federation. After isolation of the highly pathogenic influenza A (H5N8) virus in the territory of the Republic of Tyva in May 2016, the virus was introduced into the west by wild birds, where it caused a massive epizootic. The death of agricultural poultry was noted in several regions of the European part of Russia and epizootics continued until the end of 2017. This paper presents the data on circulation of highly pathogenic influenza virus over the past two years. The current status regarding H5 influenza in the territory of the Russian Federation is also considered, where for the first time since 2005 a large-scale epizooty caused by the influenza virus subtype A (H5N8) was recorded. It is shown that the territory of Russia plays an important geographical role in the spread of influenza virus by wild birds from Southeast Asia to Europe and North America, and the research also suggests the possible continuation of circulation of highly pathogenic viruses in the territory of Russia

Overview of the Epidemiological Situation on Highly Pathogenic Avian Influenza Virus in Russia in 2018

Analyzed was modern epidemiological situation on highly pathogenic avian flu in 2018. Prognosis for possible further distribution of viruses in the territory of Russia was made. In 2018, the situation on highly pathogenic avian flu in Russia was challenging. This was due to the spread of the viruses clade 2.3.4.4, which caused multiple outbreaks among wild birds and poultry in European part of Russia. In addition, A/H5N6 avian influenza virus circulation was for the first time detected in the Saratov Region during routine avian influenza virus surveillance. In May, 2018 two different lineages of avian influenza A/H9N2 were isolated during the outbreaks that occurred at several poultry plants in Primorsk Territory and Amur Region of Russia. Subsequently, that virus subtype continued spreading in Russia, which was recorded by detection of the A/H9N2 influenza virus in wild birds in the Khabarovsk and Tomsk Regions of Russia. Thus, it is shown yet again that the territory of Russia plays an  important geographical role in the spread of avian influenza viruses

Initial and severe cases of influenza in 2020-2022 and population immunity prior to epidemic season

The purpose of the present work was to evaluate population immunity to influenza and molecular genetic analysis of influenza viruses detected in the Russian Federation over 2020-2022. In this study, 1344 samples of blood serum collected prior to the 2021-2022 flu season in Siberian, Southern, Far Eastern, Volga and Ural Federal Districts were studied. Seropositivity to the A/Victoria/2570/2019 vaccine strain (H1N1) pdm09 was detected in 25% to 31% of samples from the four federal districts, and in 8% of samples from the Far Eastern Federal District. Seropositivity to the A/Cambodia/e0826360/2020 strain (H3N2) was detected in 24% to 37% of the samples. The lowest population immunity was revealed to the influenza B/Washington/02/2019 vaccine strain (Victoria lineage), with < 10% of serum samples reactive to the studied strain. Since March 2020, the worldwide turnover of all seasonal respiratory viruses has sharply decreased, except of rhinoviruses. From March 2020 to June 2021, we have identified six B/Victoria influenza viruses from sporadic cases of influenza. From June 2021 to the end February 2022, the State Research Center “Vector” received 901 samples positive for influenza A(H3N2) virus RNA, two specimens positive for A(H1N1) pdm09 virus RNA, and 17 samples positive for influenza B. All studied A(H3N2) viruses belonged to the 3C.2a1b.2a2 subclade (Bangladesh group). The two verified A(H1N1) pdm09 influenza viruses belonged to the 6B.1A.5a clade. All studied influenza B viruses were assigned to the B/Victoria genetic lineage, and to 1A.3a2 subclade. The genomes of all identified viruses did not contain mutations of the NA gene responsible for drug resistance to neuraminidase inhibitors, or mutations in РA gene responsible for baloxavir resistance. All viruses tested by fluorescence assay were sensitive to oseltamivir and zanamivir. The worldwide frequency of influenza isolates resistant to antineuraminidase drugs does not exceed 1-2% of cases. Hence, oseltamivir and zanamivir provide effective treatment for seasonal influenza

CHARACTERIZATION OF AVIAN INFLUENZA H5N8 VIRUS STRAINS THAT CAUSED THE OUTBREAKS IN THE RUSSIAN FEDERATION IN 2016–2017

Objective of the study is to investigate biological properties of avian influenza virus strains that caused the outbreaks in Russia in 2016–2017.Materials and methods. The study was performed using advanced virological and molecular-biological methods in state-of-the-art equipment.Results and conclusion. In 2016, the outbreaks among wild birds and poultry caused by highly pathogenic avian influenza H5N8 virus have occurred in the territory of the Russian Federation. In May, 2016 an outbreak of H5N8 among wild birds was registered in the territory of the Republic of Tyva. In October-November, 2016 influenza virus H5N8 was isolated in the territory of the Republics of Tatarstan and Kalmykia, Krasnodar and Astrakhan Regions of Russia. In 2017 avian influenza H5N8 has become widespread in European part of Russia and caused multiple outbreaks among wild birds and poultry. Results of the investigations of the isolated strains show that all of them are highly pathogenic and belong to the clade 2.3.4.4. Molecular-genetic and virological analysis has revealed the differences between the viruses isolated in 2016–2017 and the virus of the same clade 2.3.4.4 that was isolated in 2014

SEVERE CASES OF SEASONAL INFLUENZA IN RUSSIA IN 2015 - 2016 AND 2016 - 2017

Aim. Evaluation of seroprevalence of antibodies to influenza A and В viruses and analysis of specimens from severe or fatal influenza cases in Russia in 2015 - 2016 and 2016 - 2017 flu seasons. Materials and methods. Determination of antibody titer in human serum samples in hemagglutination inhibition assay with reference antigens. Isolation of influenza viruses from nasopharyngeal swabs and autopsy material in cell culture. Characterization ofisolated strains. Results. In 2016, compared to 2015, the proportion of serum samples, containing antibodies to influenza viruses A(H 1N1 pdm09) and A(H3N2), increased. During the 2015-2016 season, elevated number of severe and fatal cases of influenza were registered. The majority of circulated strains belonged to the new clade 6B.1 of A(HlNippdm09 viruses. 1% of analyzed isolates carried H275Y amino acid substitution in neuraminidase and were resistant to oseltamivir. In the 2016 - 2017 season, there were less severe cases of influenza. The most prevalent were influenza viruses A(H3N2) and B/Victoria. Isolated H3N2 viruses belonged to the 3C.2a subclade and B/Victoria isolates were from the 1A genetic group. All tested strains were susceptible to neuraminidase inhibitors. Conclusions. Flu seasons 2015 - 2016 and 2016 - 2017 differed in intensity of influenza activity and in the dominant influenza A virus subtype. Immunization with vaccine, comprising new HlNlpdm09-component, is crucial for prophylaxis of influenza infection with viruses from 6B. 1 subclade in the next season. Neuraminidase inhibitors are recommended for influenza treatment

Correction: Severe cases of seasonal influenza in Russia in 2017-2018.

[This corrects the article DOI: 10.1371/journal.pone.0220401.]

Severe cases of seasonal influenza in Russia in 2017-2018.

The 2017-2018 influenza epidemic season in Russia was characterized by a relatively low morbidity and mortality. We evaluated herd immunity prior to the 2017-2018 influenza season in hemagglutination inhibition assay, and performed characterization of influenza viruses isolated from severe or fatal influenza cases and from influenza cases in people vaccinated in the fall of 2017. During the 2017-2018 epidemic season, 87 influenza A and B viruses were isolated and viruses of the 75 influenza cases, including selected viral isolates and viruses analyzed directly from the original clinical material, were genetically characterized. The analyzed A(H1N1)pdm09 viruses belonged to clade 6B.1, B/Yamagata-like viruses belonged to clade 3, and B/Victoria-like viruses belonged to clade 1A and they were antigenically similar to the corresponding vaccine strains. A(H3N2) viruses belonged to clade 3C.2a and were difficult to characterize antigenically and the analysis indicated antigenic differences from the corresponding egg-grown vaccine strain. The next generation sequencing revealed the presence of D222/G/N polymorphism in the hemagglutinin gene in 32% of the analyzed A(H1N1)pdm09 lethal cases. This study demonstrated the importance of monitoring D222G/N polymorphism, including detection of minor viral variants with the mutations, in the hemagglutinin gene of A(H1N1)pdm09 for epidemiological surveillance. One strain of influenza virus A(H1N1)pdm09 was resistant to oseltamivir and had the H275Y amino acid substitution in the NA protein. All other isolates were susceptible to NA inhibitors. Prior to the 2017-2018 epidemic season, 67.4 million people were vaccinated, which accounted for 46.6% of the country's population. Just before the epidemic season 33-47% and 24-30% of blood sera samples collected within the territory of Russia showed the presence of protective antibody titers against vaccine strains of influenza A and influenza B/Victoria-like, respectively. Mass vaccination of the population had evidently reduced the severity of the flu epidemic during the 2017-2018 influenza epidemic season in Russia