Highly pathogenic avian influenza (HPAI) has caused widespread mortality in both wild and domestic birds in Europe during 2020-2022. Virus types H5N8 and H5N1 have dominated the epidemic. Isolated spill-over infections in mammals started to emerge as the epidemic continued. In autumn 2021, HPAI H5N1 caused a series of mass mortality events in farmed and released pheasants (Phasianus colchicus) in a restricted area in southern Finland. Later, in the same area, an otter (Lutra lutra), two red foxes (Vulpes vulpes) and a lynx (Lynx lynx) were found moribund or dead and infected with H5N1 HPAI virus. Phylogenetically, H5N1 strains from pheasants and mammals clustered together. Molecular analyses of the four mammalian virus strains revealed mutations in the PB2 gene segment (PB2-E627K and PB2-D701N) that are known to facilitate viral replication in mammals. This study revealed that avian influenza cases in mammals were spatially and temporally connected with avian mass mortalities suggesting increased infection pressure from birds to mammals.
FinlandHighly pathogenic avian influenza H5N1HumanMutationPheasantWild mammalGalliformesInfluenza A virusInfluenza A Virus, H5N1 SubtypeInfluenza in BirdsLynxOttersAnimalsFinlandFoxes
Structured evidence records
Evidence records
4 total
Cross Species Transmission1 records
Cross Species TransmissionExtraction confidence 0.90
Key finding
H5N1 highly pathogenic avian influenza virus transmitted from pheasants to wild carnivores including an otter, red foxes, and a lynx in Finland.
Later, in the same area, an otter (Lutra lutra), two red foxes (Vulpes vulpes) and a lynx (Lynx lynx) were found moribund or dead and infected with H5N1 HPAI virus. Phylogenetically, H5N1 strains from pheasants and mammals clustered together.
H5N1 viruses from pheasants and wild carnivores in Finland shared a phylogenetic cluster, and mammalian strains exhibited PB2 mutations associated with adaptation to mammalian hosts.
Phylogenetically, H5N1 strains from pheasants and mammals clustered together. Molecular analyses of the four mammalian virus strains revealed mutations in the PB2 gene segment (PB2-E627K and PB2-D701N) that are known to facilitate viral replication in mammals.
Genes or proteins
PB2
Analysis methods
phylogenetic analysis; molecular analysis
Molecular Adaptation1 records
Molecular AdaptationExtraction confidence 0.95
Key finding
H5N1 isolates from wild mammals in Finland carried PB2-E627K and PB2-D701N mutations that enhance viral replication in mammalian hosts.
Molecular analyses of the four mammalian virus strains revealed mutations in the PB2 gene segment (PB2-E627K and PB2-D701N) that are known to facilitate viral replication in mammals.
Genes or proteins
PB2
Mutations
PB2-E627K; PB2-D701N
Mechanism types
replication_efficiency; polymerase_activity
Spillover Event1 records
Spillover EventExtraction confidence 0.95
Key finding
H5N1 highly pathogenic avian influenza spilled over from pheasants to wild carnivores (otter, fox, lynx) in Finland.
Later, in the same area, an otter (Lutra lutra), two red foxes (Vulpes vulpes) and a lynx (Lynx lynx) were found moribund or dead and infected with H5N1 HPAI virus. Phylogenetically, H5N1 strains from pheasants and mammals clustered together.
