North Atlantic Migratory Bird Flyways Provide Routes for Intercontinental Movement of Avian Influenza Viruses

Avian influenza virus (AIV) in wild birds has been of increasing interest over the last decade due to the emergence of AIVs that cause significant disease and mortality in both poultry and humans. While research clearly demonstrates that AIVs can move across the Pacific or Atlantic Ocean, there has been no data to support the mechanism of how this occurs. In spring and autumn of 2010 and autumn of 2011 we obtained cloacal swab samples from 1078 waterfowl, gulls, and shorebirds of various species in southwest and west Iceland and tested them for AIV. From these, we isolated and fully sequenced the genomes of 29 AIVs from wild caught gulls (Charadriiformes) and waterfowl (Anseriformes) in Iceland. We detected viruses that were entirely (8 of 8 genomic segments) of American lineage, viruses that were entirely of Eurasian lineage, and viruses with mixed American-Eurasian lineage. Prior to this work only 2 AIVs had been reported from wild birds in Iceland and only the sequence from one segment was available in GenBank. This is the first report of finding AIVs of entirely American lineage and Eurasian lineage, as well as reassortant viruses, together in the same geographic location. Our study demonstrates the importance of the North Atlantic as a corridor for the movement of AIVs between Europe and North America.

近十年来，野生鸟类中的禽流感病毒（Avian Influenza Virus, AIV）因出现可在家禽与人类中引发严重疾病及死亡的毒株，而受到日益广泛的关注。尽管已有研究明确证实A型流感病毒可跨太平洋或大西洋进行跨洋传播，但目前尚无相关数据阐明其具体传播机制。2010年春、秋季及2011年秋季，研究团队在冰岛西南部与西部地区采集了1078份来自不同物种的水禽、鸥类与滨鸟的泄殖腔拭子样本，并针对A型流感病毒开展检测。基于上述样本，研究团队从冰岛野生捕获的鸥形目（Charadriiformes）鸟类与雁形目（Anseriformes）水禽中分离得到29株A型流感病毒，并完成其全基因组测序。检测结果显示，这批毒株涵盖全部8个基因组片段均属于美洲谱系的病毒、全片段均属于欧亚谱系的病毒，以及兼具美洲-欧亚混合谱系的病毒。在本研究开展前，冰岛野生鸟类中仅报道过2株A型流感病毒，且GenBank数据库中仅公开了其中1个基因组片段的序列。本研究首次报道在同一地理区域内同时检出美洲谱系、欧亚谱系及重配型A型流感病毒。本研究证实了北大西洋作为A型流感病毒在欧洲与北美之间跨洋迁徙传播通道的重要性。