Using serological approaches to investigate incursions of non-notifiable low pathogenicity avian influenza virus into UK poultry over a 10-year period

Avian influenza viruses (AIVs) are subtyped according to their two envelope glycoproteins, haemagglutin (HA) and neuraminidase (NA). Sixteen HA and nine NA subtypes circulate in avian species globally, with H5 and H7 subtypes being notifiable. These notifiable subtypes are generally associated with high pathogenicity AIV infection of poultry although low pathogenicity H5 and H7 infections can occur in poultry in the complete absence of clinical disease. Importantly, other subtypes are also capable of causing invasive disease in poultry and as such defining the baseline circulation of AIVs in both wild birds and poultry in the UK is critical to understanding risk of emergence as well as the potential for reassortment during an outbreak event. Sera were obtained from 204 UK poultry flocks, collected originally during 2012-2023 for notifiable avian disease surveillance. This H5/H7 antibody negative sample set were investigated for antibodies to non-notifiable AIVs. Generic AIV ELISA testing revealed that 45% (n=91/204) of flocks had detectable antibodies to non-notifiable AIVs. The highest antibody prevalence was detected in ducks (62/86=72%), followed by geese (12/50=24%), turkeys (4/14=29%) and chickens (10/48=21%). Pseudotype viruses (PV) were developed to screen these sera for antibodies to different AIV subtypes. Among these 91 AIV antibody-positive flocks, 15 (17%), 7 (8%) and 5 (6%) were positive by PV neutralisation assays (PVNA) for H11, H3 and H4 reactive antibodies, respectively. These results indicate that a diverse spectrum of AIV subtypes circulate in UK poultry, with seroprevalences differing between the various poultry species.

Cecilia Di Genova1, Maisie Airey1, Saumya S. Thomas1, Jacob Peers-Dent1, Scott M Reid1, Nigel Temperton3, Marek J. Slomka1, Joe James1,2, Ashley C. Banyard1,2 1Animal and Plant Health Agency (APHA), Weybridge, Surrey KT15 3NB, United Kingdom 2WOAH/FAO International Reference Laboratory for Avian Influenza, Animal and Plant Health Agency (APHA), Weybridge, Surrey KT15 3NB, United Kingdom 3Viral Pseudotype Unit, Medway School of Pharmacy, Universities of Kent and Greenwich, Chatham Maritime, Kent ME4 4 TB, United Kingdom

Notable outbreaks, field and molecular epidemiology, and surveillance in poultry