Novel Highly Pathogenic Avian Influenza A(H5N1) Clade 2.3.4.4b Virus in Wild Birds, South Korea

Characterization of highly pathogenic avian influenza A (H5N1) viruses isolated from cats in South Korea, 2023

“…In contrast, polymerase basic (PB) 2, PB1, polymerase acidic (PA), nucleoprotein, and non-structural protein genes had their origins in LPAIV of the Eurasian lineage that circulated in China, Russia, and South Korea between 2019 and 2022. The specific source of individual gene segments appeared different, although this reassortment pattern resembled that of the South Korean genotypes I and II reported in 2022 [ 3 ]. Therefore, we classified our cat isolates as South Korean genotype III.…”

“…Genotypes of H5N1 clade 2.3.4.4b were classified as G1–G16 from Chinese avian isolates in 2021–2022. The South Korean avian isolates reported in November 2022 were classified into South Korea genotypes I and II, both of which were derived from the G10 genotype [ 2 , 3 ].…”

“…SNU-01 has shown multiple mammalian adaptations in several gene segments that enhance the polymerase activity of AIVs in mammalian hosts [ 3 , 5 , 8–14 ] ( Figure 1 (B)). Interestingly, except for D701N, which significantly contributes to mammalian adaptation, the remaining mammalian adaptive mutations were not limited to SNU-01; they were also observed in avian isolates.…”

“…Additionally, an increase in genetic diversity of H5Nx clade 2.3.4.4b was confirmed owing to reassortment among AIVs [ 1–5 ]. Several mammalian adaptive mutations already accumulated within avian populations, and these changes may play an important role in facilitating the interspecies spread of AIVs to mammals [ 3 , 5 , 8–14 ]. Ongoing monitoring is imperative to track the potential spread of these multiple mammalian adaptations within avian populations and across various regions.…”

Genetic diversity of H5N1 and H5N2 high pathogenicity avian influenza viruses isolated from poultry in Japan during the winter of 2022–2023

“…The number of genotypes in Japan in 2022–2023 was the highest since the initial outbreak of the Gs/Gd virus in 2004 ( Mase et al, 2005 ), and higher than the five genotypes identified in 2020–2021 and 2016–2017 ( Mine et al, 2022 , Takemae et al, 2017 ). Recently, multiple HPAIVs with different gene constellations have been isolated in Asian countries (e.g., China in 2021–2022 ( Yang et al, 2023 ) and Korea in 2022–2023 ( Kang et al, 2023 , Lee et al, 2023 , Seo et al, 2024 )). H5 HPAIVs of multiple genotypes (more than 60 genotypes since 2020 and 16 genotypes in 2022–2023) have also been detected in Europe ( European Food Safety Authority 2023a ).…”