Different Outcomes of Chicken Infection with UK-Origin H5N1-2020 and H5N8-2020 High-Pathogenicity Avian Influenza Viruses (Clade 2.3.4.4b)

Amanda H Seekings; Caroline J Warren; Saumya S Thomas; Fabian Z X Lean; David Selden; Benjamin C Mollett; Pauline M van Diemen; Ashley C Banyard; Marek J Slomka

doi:10.3390/v15091909

Different Outcomes of Chicken Infection with UK-Origin H5N1-2020 and H5N8-2020 High-Pathogenicity Avian Influenza Viruses (Clade 2.3.4.4b)

Viruses. 2023 Sep 12;15(9):1909. doi: 10.3390/v15091909.

Authors

Amanda H Seekings¹, Caroline J Warren¹, Saumya S Thomas¹, Fabian Z X Lean², David Selden², Benjamin C Mollett¹, Pauline M van Diemen¹, Ashley C Banyard^{1

3}, Marek J Slomka¹

Affiliations

¹ Department of Virology, Animal and Plant Health Agency (APHA), Addlestone, Surrey KT15 3NB, UK.
² Department of Pathology and Animal Sciences, Animal and Plant Health Agency (APHA), Addlestone, Surrey KT15 3NB, UK.
³ WOAH/FAO International Reference Laboratory for Avian Influenza, Swine Influenza and Newcastle Disease, Animal and Plant Health Agency (APHA), Addlestone, Surrey KT15 3NB, UK.

Abstract

Clade 2.3.4.4 H5Nx highly pathogenic avian influenza viruses (HPAIVs) of the "goose/Guangdong" lineage have caused a series of European epizootics since 2014. During autumn/winter 2020-2021, several H5Nx subtypes were detected in the UK, with H5N8 being the dominant subtype in wild birds and poultry. Despite the greater subtype diversity (due to viral neuraminidase gene reassortment) reported in wild birds, only H5N8 and H5N1 subtypes caused clade 2.3.4.4 UK HPAIV poultry outbreaks during this period. The direct inoculation of layer chickens showed that H5N8-2020 was more infectious than H5N1-2020, which supported the European H5N8 dominance during that season. However, the mean death time was longer for H5N8-2020 (3.42 days) than for H5N1-2020 (2.17 days). Transmission from directly infected to naive in-contact chickens was inefficient for both subtypes. Histological lesions, the tissue dissemination of viral antigen, and nucleic acid were more extensive and abundant and accumulated more rapidly for H5N1-2020 compared with H5N8-2020. Although inefficient, H5N1-2020 transmission was faster, with its greater virulence indicating that this subtype posed a major concern, as subsequently shown during H5N1 dominance of the clade 2.3.4.4 epizootic since autumn 2021. An evaluation of these in vivo viral characteristics is key to understanding the continuing poultry threats posed by clade 2.3.4.4 H5Nx HPAIVs.

Keywords: HPAIV; avian influenza; chicken; infection; pathogenesis; transmission.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Animals
Chickens
Influenza A Virus, H5N1 Subtype* / genetics
Influenza A Virus, H5N8 Subtype* / genetics
Influenza A virus* / genetics
United Kingdom / epidemiology
Virulence

Grants and funding

This research was funded by the UK Department for Environment, Food and Rural Affairs (Defra) and the devolved Scottish and Welsh administrations under grant numbers SE2213 (FLUFUTURES 2), SV3400, and SV3032 (both under Defra Contract C).