Highly Pathogenic Avian Influenza A(H5N1) Virus Clade 2.3.4.4b Infections in Seals, Russia, 2023.

Highly pathogenic avian influenza A(H5N1) virus was detected in dead seals on Tyuleniy Island in eastern Russia, in the Sea of Okhotsk. Viruses isolated from dead northern fur seals belong to clade 2.3.4.4b and are closely related to viruses detected predominantly in the Russian Far East and Japan in 2022-2023.

Avian Influenza Virus and Avian Paramyxoviruses in Wild Waterfowl of the Western Coast of the Caspian Sea (2017-2020).

The flyways of many different wild waterfowl pass through the Caspian Sea region. The western coast of the middle Caspian Sea is an area with many wetlands, where wintering grounds with large concentrations of birds are located. It is known that wild waterfowl are a natural reservoir of the influenza A virus. In the mid-2000s, in the north of this region, the mass deaths of swans, gulls, and pelicans from high pathogenicity avian influenza virus (HPAIV) were noted. At present, there is still little known about the presence of avian influenza virus (AIVs) and different avian paramyxoviruses (APMVs) in the region's waterfowl bird populations. Here, we report the results of monitoring these viruses in the wild waterfowl of the western coast of the middle Caspian Sea from 2017 to 2020. Samples from 1438 individuals of 26 bird species of 7 orders were collected, from which 21 strains of AIV were isolated, amounting to a 1.46% isolation rate of the total number of samples analyzed (none of these birds exhibited external signs of disease). The following subtypes were determined and whole-genome nucleotide sequences of the isolated strains were obtained: H1N1 (n = 2), H3N8 (n = 8), H4N6 (n = 2), H7N3 (n = 2), H8N4 (n = 1), H10N5 (n = 1), and H12N5 (n = 1). No high pathogenicity influenza virus H5 subtype was detected. Phylogenetic analysis of AIV genomes did not reveal any specific pattern for viruses in the Caspian Sea region, showing that all segments belong to the Eurasian clades of classic avian-like influenza viruses. We also did not find the amino acid substitutions in the polymerase complex (PA, PB1, and PB2) that are critical for the increase in virulence or adaptation to mammals. In total, 23 hemagglutinating viruses not related to influenza A virus were also isolated, of which 15 belonged to avian paramyxoviruses. We were able to sequence 12 avian paramyxoviruses of three species, as follows: Newcastle disease virus (n = 4); Avian paramyxovirus 4 (n = 5); and Avian paramyxovirus 6 (n = 3). In the Russian Federation, the Newcastle disease virus of the VII.1.1 sub-genotype was first isolated from a wild bird (common pheasant) in the Caspian Sea region. The five avian paramyxovirus 4 isolates obtained belonged to the common clade in Genotype I, whereas phylogenetic analysis of three isolates of Avian paramyxovirus 6 showed that two isolates, isolated in 2017, belonged to Genotype I and that an isolate identified in 2020 belonged to Genotype II. The continued regular monitoring of AIVs and APMVs, the obtaining of data on the biological properties of isolated strains, and the accumulation of information on virus host species will allow for the adequate planning of epidemiological measures, suggest the most likely routes of spread of the virus, and assist in the prediction of the introduction of the viruses in the western coastal region of the middle Caspian Sea.

Stable Isotope Analysis Reveals Common Teal (Anas crecca) Molting Sites in Western Siberia: Implications for Avian Influenza Virus Spread.

The wetlands of southwestern Siberia (SWS) are a crossroads of bird migration routes, bringing avian influenza (AIV) strains that were previously isolated in different regions of the continent to Siberia. It is known that Anseriformes that breed in SWS migrate for the winter to central Hindustan or further west, while their migration routes to southeast Asia (SEA) remain unconfirmed. Here, we mapped the molting sites of the migrating Common Teals (Anas crecca) via analyzing stable hydrogen isotope content in feathers of hunters' prey and supplemented the analysis with the genetic structure of viruses isolated from teals in the same region. Post-breeding molt of autumn teals most likely occurred within the study region, whereas probable pre-breeding molting grounds of spring teals were in the south of Hindustan. This link was supported by viral phylogenetic analysis, which showed a close relationship between SWS isolates and viruses from south and southeast Asia. Most viral segments have the highest genetic similarity and the closest phylogenetic relationships with viruses from teal wintering areas in southeast Asian countries, including India and Korea. We assume that the winter molt of SWS breeding teals on the Hindustan coast suggests contacts with the local avifauna, including species migrating along the coast to SEA. Perhaps this is one of the vectors of AIV transmission within Eurasia.

Genetic Diversity of the Human Adenovirus C Isolated from Hospitalized Children in Russia (2019-2022).

The human adenovirus (HAdV) is a common pathogen in children that can cause acute respiratory virus infection (ARVI). However, the molecular epidemiological and clinical information relating to HAdV among hospitalized children with ARVI is rarely reported in Russia. A 4-year longitudinal (2019-2022) study among hospitalized children (0-17 years old) with ARVI in Novosibirsk, Russia, was conducted to evaluate the epidemiological and molecular characteristics of HAdV. Statistically significant differences in the detection rates of epidemiological and virological data of all positive viral detections of HAdV were analyzed using a two-tailed Chi-square test. The incidence of HAdV and other respiratory viruses such as human influenza A and B viruses, respiratory syncytial virus, coronavirus, parainfluenza virus, metapneumovirus, rhinovirus, bocavirus, and SARS-CoV-2 was investigated among 3190 hospitalized children using real-time polymerase chain reaction. At least one of these respiratory viruses was detected in 74.4% of hospitalized cases, among which HAdV accounted for 4%. A total of 1.3% co-infections with HAdV were also registered. We obtained full-genome sequences of 12 HAdVs, which were isolated in cell cultures. Genetic analysis revealed the circulation of adenovirus of genotypes C1, C2, C5, C89, and 108 among hospitalized children in the period from 2019-2022.

Virological and Genetic Characterization of the Unusual Avian Influenza H14Nx Viruses in the Northern Asia.

Wild aquatic birds are generally identified as a natural reservoir of avian influenza viruses (AIVs), where a high diversity of subtypes has been detected. Some AIV subtypes are considered to have relatively low prevalence in wild bird populations. Six-year AIV surveillance in Siberia revealed sporadic cases of the rarely identified H14-subtype AIV circulation. Complete genome sequencing of three H14 isolates were performed, and the analysis indicated interconnections between low pathogenic avian influenza (LPAI) viruses. We conducted hemagglutination inhibition and virus neutralization assays, estimated the susceptibility of isolates to neuraminidase inhibitors, and characterized receptor specificity. Our study revealed circulation of a new H14N9 subtype described for the first time. However, the low prevalence of the H14-subtype AIV population may be the reason for the underestimation of the diversity of H14-subtype AIVs. According to the available data, a region in which H14-subtype viruses were detected several times in 2007-2022 in the Eastern Hemisphere is Western Siberia, while the virus was also detected once in South Asia (Pakistan). Phylogenetic analysis of HA segment sequences revealed the circulation of two clades of H14-subtype viruses originated from initial 1980s Eurasian clade; the first was detected in Northern America and the second in Eurasia.

Virological and genetic characteristics of human respiratory syncytial viruses isolated in Russia, 2017-2018.

Isolation of human respiratory syncytial virus (HRSV) from clinical samples and storage of isolates for long period remains a considerable problem. We describe in detail the optimized conditions of HRSV isolation and cultivation in three cell cultures HeLa, HEp-2, and Vero. HRSV was detected in 35.2% (166/471) specimens by real-time PCR from symptomatic infants and children up to 15 years from October 2017 to March 2018 in Russia. HRSV-positive samples were used for virus isolation in HeLa, HEp-2, and Vero cells in different manners (in monolayer or suspension). To optimize the conditions of HRSV cultivation, these cell cultures were treated or not with receptor-destroying enzyme (RDE). Ten isolates were successfully obtained by the way of infection of the suspension of cells with subsequent RDE treatment. Among them, several isolates induced the cytopathogenic effect (CPE) by the syncytium formation in both Hela and HEp-2 cell cultures. The genetic analysis revealed that the manners of isolation by using monolayer or suspension and subsequent RDE treatment did not influence the nucleotide and amino acid structures of obtained HRSVs. The CPE characteristics of obtained viruses were the same in HeLa, HEp-2, and Vero cell cultures, and were described as large syncytium up to 150 microns or more in size with the nuclei peripheral location and an optically bright zone in the center of the formation. We showed that infection of cell suspension with the subsequent RDE treatment increased the chance of HRSVs isolation from clinical samples.

Does Avian Coronavirus Co-Circulate with Avian Paramyxovirus and Avian Influenza Virus in Wild Ducks in Siberia?

Avian coronaviruses (ACoV) have been shown to be highly prevalent in wild bird populations. More work on avian coronavirus detection and diversity estimation is needed for the breeding territories of migrating birds, where the high diversity and high prevalence of Orthomyxoviridae and Paramyxoviridae have already been shown in wild birds. In order to detect ACoV RNA, we conducted PCR diagnostics of cloacal swab samples from birds, which we monitored during avian influenza A virus surveillance activities. Samples from two distant Asian regions of Russia (Sakhalin region and Novosibirsk region) were tested. Amplified fragments of the RNA-dependent RNA-polymerase (RdRp) of positive samples were partially sequenced to determine the species of Coronaviridae represented. The study revealed a high presence of ACoV among wild birds in Russia. Moreover, there was a high presence of birds co-infected with avian coronavirus, avian influenza virus, and avian paramyxovirus. We found one case of triple co-infection in a Northern Pintail (Anas acuta). Phylogenetic analysis revealed the circulation of a Gammacoronavirus species. A Deltacoronavirus species was not detected, which supports the data regarding the low prevalence of deltacoronaviruses among surveyed bird species.

Changes in the Etiology of Acute Respiratory Infections among Children in Novosibirsk, Russia, between 2019 and 2022: The Impact of the SARS-CoV-2 Virus.

A wide range of human respiratory viruses are known that may cause acute respiratory infections (ARIs), such as influenza A and B viruses (HIFV), respiratory syncytial virus (HRSV), coronavirus (HCoV), parainfluenza virus (HPIV), metapneumovirus (HMPV), rhinovirus (HRV), adenovirus (HAdV), bocavirus (HBoV), and others. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) caused the COronaVIrus Disease (COVID) that lead to pandemic in 2019 and significantly impacted on the circulation of ARIs. The aim of this study was to analyze the changes in the epidemic patterns of common respiratory viruses among children and adolescents hospitalized with ARIs in hospitals in Novosibirsk, Russia, from November 2019 to April 2022. During 2019 and 2022, nasal and throat swabs were taken from a total of 3190 hospitalized patients 0-17 years old for testing for HIFV, HRSV, HCoV, HPIV, HMPV, HRV, HAdV, HBoV, and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) by real-time PCR. The SARS-CoV-2 virus dramatically influenced the etiology of acute respiratory infections among children and adolescents between 2019 and 2022. We observed dramatic changes in the prevalence of major respiratory viruses over three epidemic research seasons: HIFV, HRSV, and HPIV mainly circulated in 2019-2020; HMPV, HRV, and HCoV dominated in 2020-2021; and HRSV, SARS-CoV-2, HIFV, and HRV were the most numerous agents in 2021-2022. Interesting to note was the absence of HIFV and a significant reduction in HRSV during the 2020-2021 period, while HMPV was absent and there was a significant reduction of HCoV during the following epidemic period in 2021-2022. Viral co-infection was significantly more frequently detected in the 2020-2021 period compared with the other two epidemic seasons. Certain respiratory viruses, HCoV, HPIV, HBoV, HRV, and HAdV, were registered most often in co-infections. This cohort study has revealed that during the pre-pandemic and pandemic periods, there were dramatic fluctuations in common respiratory viruses registered among hospitalized patients 0-17 years old. The most dominant virus in each research period differed: HIFV in 2019-2020, HMPV in 2020-2021, and HRSV in 2021-2022. Virus-virus interaction was found to be possible between SARS-CoV-2 and HRV, HRSV, HAdV, HMPV, and HPIV. An increase in the incidence of COVID-19 was noted only during the third epidemic season (January to March 2022).

Genetics of Japanese H5N8 high pathogenicity avian influenza viruses isolated in winter 2020-2021 and their genetic relationship with avian influenza viruses in Siberia.

In winter 2020-2021, Japan experienced multiple serious outbreaks of H5N8 high pathogenicity avian influenza (HPAI)-52 outbreaks at poultry farms and 58 cases in wild birds or the environment-that occurred simultaneously with outbreaks in Europe. Here, we examined how the H5N8 HPAI viruses (HPAIVs) emerged and spread through Japan and across the Eurasian continent. Phylogenetic and phylogeographic analyses were performed using full genetic sequences of the viruses that caused 52 outbreaks at poultry farms or were isolated from 11 infected wild birds. Genetically, the viruses showed five genotypes (E1, E2, E3, E5 and E7) that have already been reported in Korea. The viruses showing the E3 genotype were found to have caused most of the HPAI outbreaks at poultry farms and were detected over the longest period of time. The internal genes of the viruses were genetically related to those of AIVs isolated through avian influenza surveillance activities in regions of Siberia including Buryatia, Yakutia and Amur regions, suggesting that the Japanese viruses emerged via reassortment events with AIVs genetically related to Siberian AIVs. In addition, H5N2 and H5N8 HPAIVs were isolated from wild birds during surveillance activities conducted in the Novosibirsk region of Siberia in summer 2020. Phylogenetic analyses revealed that these viruses possessed haemagglutinin genes that were related to those of H5N8 HPAIVs that were circulating in Europe in winter 2020-2021. These results suggest that the viruses in wild birds during summer in Siberia most likely spread in both Asia and Europe the following winter. Together, the present results emphasize the importance of continual monitoring of AIVs in Siberia for forecasting outbreaks not only in Asia but also further away in Europe.

Characterization and Phylodynamics of Reassortant H12Nx Viruses in Northern Eurasia.

Wild waterfowl birds are known to be the main reservoir for a variety of avian influenza viruses of different subtypes. Some subtypes, such as H2Nx, H8Nx, H12Nx, and H14Nx, occur relatively rarely in nature. During 10-year long-term surveillance, we isolated five rare H12N5 and one H12N2 viruses in three different distinct geographic regions of Northern Eurasia and studied their characteristics. H12N2 from the Far East region was a double reassortant containing hemagglutinin (HA), non-structural (NS) and nucleoprotein (NP) segments of the American lineage and others from the classical Eurasian avian-like lineage. H12N5 viruses contain Eurasian lineage segments. We suggest a phylogeographical scheme for reassortment events associated with geographical groups of aquatic birds and their migration flyways. The H12N2 virus is of particular interest as this subtype has been found in common teal in the Russian Far East region, and it has a strong relation to North American avian influenza virus lineages, clearly showing that viral exchange of segments between the two continents does occur. Our results emphasize the importance of Avian Influenza Virus (AIV) surveillance in Northern Eurasia for the annual screening of virus characteristics, including the genetic constellation of rare virus subtypes, to understand the evolutionary ecology of AIV.