부산대학교 도서관

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. Author summary: The recent first detection of highly pathogenic avian influenza (HPAI) virus in wild birds inhabiting the Atlantic Flyway of North America (Newfoundland, Canada in November 2021 and South Carolina, USA, in January 2022) raises concern for virus movement within this region. Here, we study IAV in wild waterfowl with focus on bird movements in combination with IAV prevalence, seroprevalence, and genetic analyses for hypothesized virus flow and persistence. Migratory connectivity for two important dabbling duck species within the AF was indicated by banding records from the North American Bird Banding Program. A broad diversity of viral subtypes including H1, H3, H4, H6, H8–11, N1–4, N6, N8–N9 was detected in these species. Prevalence of active infections was higher on the breeding than wintering grounds, and common to other studies, the reverse was seen for antibody prevalence. Genetic analysis indicated the possibility of virus persistence from one year to the next in the northern latitudes on the breeding grounds, and although no full genome movement was detected between the breeding and wintering sites, viral gene flow was evident. The contribution of these findings in relation to bird movements will help guide surveillance as HPAI is detected within the flyway. [ABSTRACT FROM AUTHOR]