88 Investigating highly pathogenic avian influenza variant associations with wild bird species in the New England region of the Atlantic Flyway to examine the role of host ecology in variant fitness

Objectives/Goals: Identify host ecology factors that lead to the emergence of highly pathogenic avian influenza (HPAI) variants shown to be more fit than others and that become variants of concern to agriculture, wildlife, and humans. Goals include targeted surveillance for these variants for enhanced biosecurity measures in agriculture and pandemic preparedness. Methods/Study Population: The study dataset of 721 HPAI-positive cases in wild birds in New England since 2022 was collected through a robust sampling effort by Tufts’ Runstadler Laboratory together with a large network of wildlife rescue and rehabilitation partners. We will fit mixed-effects models to measure the association of variant fitness as a fixed effect with the odds of infection in species of either of the two bird orders most associated with HPAI – gulls and shorebirds or ducks and geese. Variant will be fit as a random effect, and covariates will include ecological factors. Fitness will be a leveled variable based on prevalence, geographic spread and host range. Using centroid spatial statistics, we will determine whether these variants traveled geographically distinct transmission routes, indicating distinct host ecologies. Results/Anticipated Results: We anticipate that birds of the order Charadriiformes (seagulls and shorebirds) will be more associated than Anseriformes (ducks, geese) with HPAI variants that were not transmitted beyond the region and that the reverse will be true with variants that did achieve prevalence over a wide geographic range and range of host species, including agricultural species. We also anticipate that there are distinct transmission routes by variant that could better illuminate host ecology dynamics in this region that contribute to variant fitness. Discussion/Significance of Impact: The current HPAI virus outbreak is perpetuated by evolution to new variants through co-infections in wild birds with low pathogenic avian influenza viruses they carry. This research could lead to study of the virulence to different wild bird host species of low pathogenic avian influenza subtypes that contributed genetic material to an HPAI variant.