In 2021, several isolates of the H5N5 avian influenza virus (AIV) were detected in Europe and the Russian Federation, which differed from those detected in 2020. Genetic analysis revealed a relationship between the highly pathogenic avian influenza H5N5 subtype, detected in Europe, and some isolates detected in the Russian Federation territory in 2020–2021: it was shown that both originated in the Caspian Sea regions around the autumn of 2020. The appearance of H5N5 subtype viruses in the spring of 2021 in Europe and the Russian Federation was not associated with the mass migration of birds from Africa. The results of the analysis revealed the presence of a deletion in the stem of a neuraminidase between bp 139 and 204 (open reading frame). It has been shown that AIVs of the H5N5 subtype are capable of long-term circulation in wild bird populations with the possibility of reassortment. The results also highlighted the need for careful monitoring of the circulation of AIVs in the Caspian Sea region, the role of which, in the preservation and emergence of new antigenic variants of such viruses in Eurasia, is currently underestimated.

High pathogenicity avian influenza (HPAI) has impacted poultry and wild birds globally. The number of H5 HPAI virus (HPAIV) infection cases in wild birds in Hokkaido (Northern Japan) was high in the last two seasons, contributing to virus spillover to resident birds and poultry. Therefore, H5 HPAIVs in birds and mammals in Hokkaido in winter 2022–2023 and 2023–2024 were monitored and viruses were phylogenetically, antigenically, and pathogenetically characterized. Thirty HPAIV isolates were subtyped and pathotyped by sequencing the hemagglutinin (HA) gene of viruses. Phylogenetic analysis of the HA gene revealed that all isolated HPAIVs were categorized into clade 2.3.4.4b and divided into three groups (G2b, G2c, and G2d). Most isolates belonging to subgroup G2d clustered with isolates in winter 2021–2022 in Hokkaido. The other isolates were categorized into two subgroups, G2b and G2c, mainly composed of isolates in Honshu Island in winter 2021–2022 and 2022–2023, respectively. Two H5 HPAIVs isolated in Eastern Russia in spring and autumn 2022 were genetically close to most Hokkaido isolates (G2d), and a virus isolated in Hokkaido in November 2023 was also grouped in subgroup G2d. Further analysis of all eight gene segments identified six types of gene constellations. Cross‐hemagglutination inhibition test indicated that the antigenicity of H5 HPAIVs isolated in the last several seasons was similar within them but slightly different from that in the 2010s. Three chicken breeds were intranasally challenged with four representative isolates to assess their pathogenicity. All chickens except one broiler chicken were dead until 5‐day postchallenge with different pathogenicity of these viruses. The pathogenicity of one HPAIV strain was significantly lower in broiler chickens than in layer chickens. The mixture of multiple characteristics of HPAIVs in Hokkaido was confirmed by bird migration routes. Thus, many HPAIVs can be brought and scattered anywhere on Earth.

Newcastle disease virus (NDV, Avian orthoavulavirus type 1, AOAV-1) is a contagious high-impact poultry pathogen with infections detected worldwide. In the present study, 19,500 clinical samples from wild bird species and poultry collected from 28 regions of Russia between 2017 and 2021 were screened for the presence of the AOAV-1 genome. NDV RNA was detected in 15 samples from wild birds and 63 samples from poultry. All isolates were screened for a partial sequence of the fusion (F) gene that included the cleavage site. Phylogenetic analysis demonstrated that lentogenic AOAV-1 I.1.1, I.1.2.1, and II genotypes were dominant among vaccine-like viruses in the territory of the Russian Federation. A vaccine-like virus with a mutated cleavage site (112-RKQGR^L-117) was detected in turkeys. Among the virulent AOAV-1 strains, viruses of the XXI.1.1, VII.1.1, and VII.2 genotypes were identified. The cleavage site of viruses of the XXI.1.1 genotype had a 112-KRQKR^F-117 amino acid sequence. The cleavage site of viruses with VII.1.1 and VII.2 genotypes had a 112-RRQKR^F-117 amino acid sequence. The data collected by the present study demonstrate the distribution and dominance of the virulent VII.1.1 genotype in the Russian Federation between 2017 and 2021.

More than 30,000 samples of blood serum from domestic, wild and synanthropic birds from 50 regions of the Russian Federation were submitted to the FGBI “ARRIAH” (Vladimir) Reference Laboratory for Avian Viral Diseases to be tested for avian influenza and Newcastle disease within the framework of monitoring activities conducted by the Rosselkhoznadzor in 2019. As a result of the laboratory diagnosis, antibodies to type A influenza virus were detected in vaccinated chickens from two poultry farms in the Perm and Primorsky Krais (A/N9). The detected antibodies were specific to the haemagglutinin subtype of the vaccine antigen. As for the backyards in the RF Subjects, where scheduled vaccination against avian influenza A/H5 is carried out, a low level of immunity was seen in the Rostov and Astrakhan Oblasts (35 and 44%, respectively) while a high level of immunity was observed in the Republic of Altai, Krasnodar Krai, the Chechen Republic and the Primorsky Krai (69, 78, 80 and 88%, respectively). High seroprevalence of Newcastle disease virus in adult poultry in indoor holdings was associated with mass vaccination against the disease. In broiler chickens, post-vaccination antibodies were observed, on average, in 42% of the studied blood serum samples. Antibodies to the Newcastle disease virus were detected in 39% of samples from backyard chickens. Seroprevalence in wild and synanthropic birds was high. The obtained results suggest that the risk of introduction and spread of avian influenza and Newcastle disease in industrial poultry farms and in backyards remains.

Between 2019 and 2023, 163 cases of subgenotype VII.1.1 Newcastle disease virus infection were registered in backyard poultry in the Russian Federation within the framework of epizootiological monitoring. Subgenotype VII.1.1 Newcastle disease virus was reported in a total of 18 different subjects of the Russian Federation. Most of the Newcastle disease outbreaks caused by the viruses of this subgenotype occurred in the autumn and winter period (60%). Further tests allowed for the determination of complete F and HN gene nucleotide sequences for 40 isolates. The results were used to perform the Bayesian analysis of F gene sequences with BEAST v.1.10.4 software. The obtained nucleotide substitution accumulation rates were practically non-dependent on the selected nucleotide substitution model and varied appreciably depending on the applied molecular clock model (0.0018 and 0.002 site-1year-1). The conducted study established that the formation of the ‘Russian’ NDV isolates of subgenotype VII.1.1 followed several stages. In the early 2000s, ancestral viruses belonging to subgenotype VII-d were detected in the Middle East and Eastern Europe. From these, through intermediate forms identified in Iraq around 2007–2008, a group designated as subgenotype VII-L emerged. This group gave rise to two sister clades: the Iranian subgenotype VII-L and the cluster of isolates from Russia and Poland, whose immediate common ancestor likely existed around 2015–2016, probably in Asia.

Influenza D virus (IDV), an emerging orthomyxovirus with zoonotic potential, infects diverse hosts, causes respiratory disease, and remains poorly characterized in China despite its global expansion. From October 2023 to January 2025, we collected 563 nasal swabs from cattle across 28 farms in Jilin Province, Northeast China, and identified seven IDV-positive samples (1.2%), recovering two viable isolates (JL/YB2024 and JL/CC2024). Full-genome sequencing revealed complete, stable seven-segment genomes with high nucleotide identity (up to 99.9%) to contemporary Chinese D/Yamagata/2019 strains and no evidence of reassortment. Maximum-likelihood and time-resolved Bayesian phylogenies of 231 global hemagglutinin-esterase-fusion (HEF) sequences placed the Jilin isolates within the East Asian D/Yamagata/2019 clade and traced their most recent common ancestor to approximately 2017 (95% highest posterior density: 2016–2018), suggesting a cross-border introduction likely associated with regional cattle movement. No IDV was detected in parallel surveillance of swine, underscoring cattle as the principal reservoir and amplifying host. Bayesian skyline analysis demonstrated a marked decline in global IDV genetic diversity during 2020–2022, coinciding with livestock-movement restrictions imposed during the COVID-19 pandemic. Collectively, these findings indicate that IDV circulation in China is sporadic and geographically localized, dominated by the D/Yamagata/2019 lineage, and shaped by multiple independent incursions rather than a single emergence. Both the incorporation of IDV diagnostics into routine bovine respiratory disease surveillance and cattle-import quarantine programs, and the adoption of a One Health framework to monitor potential human spillover and future viral evolution, were recommend.