Abstract
Global dispersion of high pathogenicity avian influenza (HPAI), especially that caused by H5 clade 2.3.4.4, has threatened poultry industries and, potentially, human health. An HPAI virus, A/northern pintail/Hokkaido/M13/2020 (H5N8) (NP/Hok/20) belonging to clade 2.3.4.4b, was isolated from a fecal sample collected at a lake in Hokkaido, Japan where migratory birds rested, October 2020. In the phylogenetic trees of all eight gene segments, NP/Hok/20 fell into in the cluster of European isolates in 2020, but was distinct from the isolates in eastern Asia and Europe during the winter season of 2017–2018. The antigenic cartography indicates that the antigenicity of NP/Hok/20 was almost the same as that of previous isolates of H5 clade 2.3.4.4b, whereas the antigenic distances from NP/Hok/20 to the representative strains in clade 2.3.4.4e and to a strain in 2.3.4 were apparently distant. These data imply that HPAI virus clade 2.3.4.4b should have been delivered by bird migration despite the intercontinental distance, although it was not defined whether NP/Hok/20 was transported from Europe via Siberia where migratory birds nest in the summer season. Given the probability of perpetuation of transmission in the northern territory, periodic updates of intensive surveys on avian influenza at the global level are essential to prepare for future outbreaks of the HPAI virus.
Highlights
Avian influenza is a highly contagious disease that is caused by infection with influenza A viruses, categorized into highly or low pathogenic influenza viruses according to its pathogenicity in chickens [1]
The sequence analyses revealed that the HA of NP/Hok/20 had multiple basic amino residues at the proteolytic cleavage site, REKRRKR/G, which is defined as a molecular marker of high pathogenicity avian influenza viruses (HPAIVs) [25]
The phylogenetic tree of the HA segment indicated that the HAs of NP/Hok/20 and the Korean strain were classified in clade 2.3.4.4b and further classified into the same cluster of European isolates in the winter season of 2019−2020, including A/chicken/Slovakia-Pah 14/2020 (H5N8), with which NP/Hok/20 showed the third highest homology (Figure 2A)
Summary
Avian influenza is a highly contagious disease that is caused by infection with influenza A viruses, categorized into highly or low pathogenic influenza viruses according to its pathogenicity in chickens [1]. Influenza A viruses originating from wild birds are subtyped by reactivity to antisera against two glycoproteins, hemagglutinin (HA) and neuraminidase (NA), on the virus surface, to H1-16 and N1-9, respectively [2]. High pathogenicity avian influenza (HPAI) viruses are limited to either. High pathogenicity avian influenza (HPAI) viruses are limited to either the H5 or H7 subtypes and possess multiple basic amino acid residues at the site of HA proteolytic the. Virus (HPAIV), which originated from the prevalent strain in domestic geese of Guangdong. Circulation of various groups of HPAIV necessitates an intensive surveillance of avian influenza virus among among wild wildand andmigratory migratorybirds birdstoto provide update virus circulation situation so provide anan update on on the the virus circulation situation so that that proper measures can be implemented to mitigate its invasion.
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