Investigating the Genetic Diversity of H5 Avian Influenza Viruses in the United Kingdom from 2020–2022

Abstract

High-pathogenicity avian influenza virus (HPAIV) outbreaks devastate avian species across all sectors, having both economic and ecological impacts through mortalities in poultry and wild birds, respectively. These viruses can also represent a significant zoonotic risk.

Transmission dynamics and pathogenesis differ between pheasants and partridges infected with clade 2.3.4.4b H5N8 and H5N1 high-pathogenicity avian influenza viruses

“…The continued circulation of H5Nx clade 2.3.4.4b HPAIVs [12,48] necessitates better understanding of its pathogenesis and transmission in different bird species. We investigated the susceptibility of ring-necked pheasants and red-legged partridges to clade 2.3.4.4b HPAIVs of the H5N8 and H5N1 subtypes, isolated from farmed UK pheasants during early 2021.…”

“…To conclude, our findings are of important interest from the perspective of understanding avian species susceptibility to the H5Nx clade 2.3.4.4 HPAIVs, particularly in view of the H5N1 subtype’s subsequent dominance in Europe and spread to the Americas [12,48,56,57]. The gamebird sector will continue to pose challenges, where it is important to assess the risks of infection spread which will be informed by the comparative resilience to infection in the relevant species.…”

“…Reassortments which include NA (and internal) gene exchanges featured in the evolution of clade 2.3.4.4 GsGd HPAIVs which are also referred to as H5Nx HPAIVs [7]. European clade 2.3.4.4 H5Nx HPAIV incursions have occurred since 2014 during the autumn / winter [8] with ensuing seasonal subtype dominance; namely H5N8 during 2014-2015, 2016-2017, 2019-2020 [9,10], H5N6 during 2018 [11] and H5N1 during the 2021-2022 epizootics [12]. However, multiple subtypes can cocirculate as during the 2020-2021 season when H5N8 predominated, wherea minority H5N1 reassortant featured six viral gene changes, namely the NA and five internal gene segments [12][13][14].…”

“…European clade 2.3.4.4 H5Nx HPAIV incursions have occurred since 2014 during the autumn / winter [8] with ensuing seasonal subtype dominance; namely H5N8 during 2014-2015, 2016-2017, 2019-2020 [9,10], H5N6 during 2018 [11] and H5N1 during the 2021-2022 epizootics [12]. However, multiple subtypes can cocirculate as during the 2020-2021 season when H5N8 predominated, wherea minority H5N1 reassortant featured six viral gene changes, namely the NA and five internal gene segments [12][13][14]. Following H5Nx GsGd HPAIV infection, wild and domesticated anseriformes display a more ameliorated pathogenesis compared to galliformes, hence ducks serve as an insidious reservoir with migratory waterfowl disseminating new infections [15,16].…”

Transmission dynamics and pathogenesis differ between pheasants and partridges infected with clade 2.3.4.4b H5N8 and H5N1 high-pathogenicity avian influenza viruses

“…Reassortments which include NA (and internal) gene exchanges have featured in the evolution of clade 2.3.4.4 GsGd HPAIVs which are also referred to as H5Nx HPAIVs [7]. European clade 2.3.4.4 H5Nx HPAIV incursions have occurred since 2014 during the autumn / winter [8] with ensuing seasonal subtype dominance; namely H5N8 during 2014–2015, 2016–2017, 2019–2020 [9, 10], H5N6 during 2018 [11] and H5N1 during the 2021–2022 epizootics [12]. However, multiple subtypes can co-circulate as during the 2020–2021 season when H5N8 predominated, whereas the minority H5N1 reassortant featured six viral gene changes, namely the NA and five internal gene segments which had reassorted [12–14].…”