Maintenance and dissemination of avian-origin influenza A virus within the northern Atlantic Flyway of North America

Abstract

Wild waterbirds, the natural reservoirs for avian influenza viruses, undergo migratory movements each year, connecting breeding and wintering grounds within broad corridors known as flyways. In a continental or global view, the study of virus movements within and across flyways is important to understanding virus diversity, evolution, and movement. From 2015 to 2017, we sampled waterfowl from breeding (Maine) and wintering (Maryland) areas within the Atlantic Flyway (AF) along the east coast of North America to investigate the spatio-temporal trends in persistence and spread of influenza A viruses (IAV). We isolated 109 IAVs from 1,821 cloacal / oropharyngeal samples targeting mallards (Anas platyrhynchos) and American black ducks (Anas rubripes), two species having ecological and conservation importance in the flyway that are also host reservoirs of IAV. Isolates with >99% nucleotide similarity at all gene segments were found between eight pairs of birds in the northern site across years, indicating some degree of stability among genome constellations and the possibility of environmental persistence. No movement of whole genome constellations were identified between the two parts of the flyway, however, virus gene flow between the northern and southern study locations was evident. Examination of banding records indicate direct migratory waterfowl movements between the two locations within an annual season, providing a mechanism for the inferred viral gene flow. Bayesian phylogenetic analyses provided evidence for virus dissemination from other North American wild birds to AF dabbling ducks (Anatinae), shorebirds (Charidriformes), and poultry (Galliformes). Evidence was found for virus dissemination from shorebirds to gulls (Laridae), and dabbling ducks to shorebirds and poultry. The findings from this study contribute to the understanding of IAV ecology in waterfowl within the AF.

Recurring Trans-Atlantic Incursion of Clade 2.3.4.4b H5N1 Viruses by Long Distance Migratory Birds from Northern Europe to Canada in 2022/2023

“…The re-introduction of new viruses and recurring local expansions of divergent or reassortant HPAI viruses within the East Coast of Canada and the USA could impact the genetic landscape within the North American flyways. Moreover, the continued movements of birds through the North American flyways that consist of three hotspots for avian influenza virus, the Delaware Bay for shorebirds and gulls, Alberta for ducks, and Chesapeake Bay, wherein millions of birds congregate, may have long-term consequences for virus diversity and new variant generation [ 33 , 34 ].…”

Insights from Avian Influenza: A Review of Its Multifaceted Nature and Future Pandemic Preparedness

“…The dissemination of AIVs within and across regions is largely influenced by the migratory movements of wild birds, which can carry and exchange different virus strains along their flyways [ 27 ]. Flyways are large corridors that connect migratory birds’ breeding and wintering grounds across continents [ 27 ].…”

“…The dissemination of AIVs within and across regions is largely influenced by the migratory movements of wild birds, which can carry and exchange different virus strains along their flyways [ 27 ]. Flyways are large corridors that connect migratory birds’ breeding and wintering grounds across continents [ 27 ]. Studies have shown, for example, that the Pacific Flyway, a migratory path connecting western North America to eastern Asia via breeding grounds in Beringia, has the potential to introduce or exchange avian influenza viruses between North America and Asia [ 27 ].…”

“…Flyways are large corridors that connect migratory birds’ breeding and wintering grounds across continents [ 27 ]. Studies have shown, for example, that the Pacific Flyway, a migratory path connecting western North America to eastern Asia via breeding grounds in Beringia, has the potential to introduce or exchange avian influenza viruses between North America and Asia [ 27 ].…”

Confirmation of Highly Pathogenic Avian Influenza (HPAI) H5N1 Associated with an Unexpected Mortality Event in South Polar Skuas (Stercorarius maccormicki) during 2023-2024 Surveillance Activities in Antarctica

“…Highly pathogenic avian influenza (HPAI) subtype H5NX, clade 2.3.4.4b has been responsible for several outbreaks worldwide causing multiple mass mortality events among avian wildlife and marine mammal populations (Charostad et al, 2023). The wide and fast dispersion of this virus is attributed to the contamination of migratory species (Caliendo et al, 2022a; Prosser et al, 2022; Gass Jr et al, 2023) and those with long-range dispersing capabilities (Boulinier, 2023; Lane et al, n.d.). On the other hand, the H5 highly pathogenic strains have undergone extensive evolution.…”