Koehler Anson V, Pearce John M, Flint Paul L, Franson J Christian, Ip Hon S
Alaska Science Center, US Geological Survey, 4210 University Drive, Anchorage, Alaska 99508, USA.
Mol Ecol. 2008 Nov;17(21):4754-62. doi: 10.1111/j.1365-294X.2008.03953.x.
The role of migratory birds in the movement of the highly pathogenic (HP) avian influenza H5N1 remains a subject of debate. Testing hypotheses regarding intercontinental movement of low pathogenic avian influenza (LPAI) viruses will help evaluate the potential that wild birds could carry Asian-origin strains of HP avian influenza to North America during migration. Previous North American assessments of LPAI genetic variation have found few Asian reassortment events. Here, we present results from whole-genome analyses of LPAI isolates collected in Alaska from the northern pintail (Anas acuta), a species that migrates between North America and Asia. Phylogenetic analyses confirmed the genetic divergence between Asian and North American strains of LPAI, but also suggested inter-continental virus exchange and at a higher frequency than previously documented. In 38 isolates from Alaska, nearly half (44.7%) had at least one gene segment more closely related to Asian than to North American strains of LPAI. Additionally, sequences of several Asian LPAI isolates from GenBank clustered more closely with North American northern pintail isolates than with other Asian origin viruses. Our data support the role of wild birds in the intercontinental transfer of influenza viruses, and reveal a higher degree of transfer in Alaska than elsewhere in North America.
候鸟在高致病性（HP）禽流感H5N1传播中的作用仍是一个有争议的话题。对低致病性禽流感（LPAI）病毒洲际传播的假设进行检验，将有助于评估野生鸟类在迁徙过程中把亚洲起源的高致病性禽流感毒株携带到北美的可能性。此前北美对LPAI基因变异的评估发现亚洲重配事件很少。在此，我们展示了对在阿拉斯加采集的针尾鸭（Anas acuta）低致病性禽流感分离株进行全基因组分析的结果，针尾鸭是一种在北美和亚洲之间迁徙的鸟类。系统发育分析证实了亚洲和北美LPAI毒株之间的基因差异，但也表明存在洲际病毒交换，且频率高于先前记录。在来自阿拉斯加的38个分离株中，近一半（44.7%）至少有一个基因片段与亚洲LPAI毒株的关系比与北美毒株的关系更密切。此外，来自GenBank的几个亚洲LPAI分离株的序列与北美针尾鸭分离株的聚类关系比与其他亚洲起源病毒的聚类关系更紧密。我们的数据支持了野生鸟类在流感病毒洲际传播中的作用，并揭示了阿拉斯加的病毒传播程度高于北美其他地区。
