US Geological Survey, Western Ecological Research Center, San Francisco Bay Estuary Field Station, Vallejo, CA 94592, USA.
Mol Ecol. 2012 Dec;21(24):5986-99. doi: 10.1111/j.1365-294X.2012.05735.x. Epub 2012 Sep 13.
Studies of pathogen transmission typically overlook that wildlife hosts can include both migrant and resident populations when attempting to model circulation. Through the application of stable isotopes in flight feathers, we estimated the migration strategy of mallards (Anas platyrhynchos) occurring on California wintering grounds. Our study demonstrates that mallards- a principal host of avian influenza virus (AIV) in nature, contribute differently to virus gene flow depending on migration strategy. No difference in AIV prevalence was detected between resident (9.6%), intermediate-distance (9.6%) and long-distance migrants (7.4%). Viral diversity among the three groups was also comparable, possibly owing to viral pool mixing when birds converge at wetlands during winter. However, migrants and residents contributed differently to the virus gene pool at wintering wetlands. Migrants introduced virus from northern breeding grounds (Alaska and the NW Pacific Rim) into the wintering population, facilitating gene flow at continental scales, but circulation of imported virus appeared to be limited. In contrast, resident mallards acted as AIV reservoirs facilitating year-round circulation of limited subtypes (i.e. H5N2) at lower latitudes. This study supports a model of virus exchange in temperate regions driven by the convergence of wild birds with separate geographic origins and exposure histories.
研究病原体传播时，通常会忽略野生动物宿主可能包括迁徙和居留种群，而试图建立循环模型。本研究通过对飞行羽毛中稳定同位素的应用，估计了加利福尼亚越冬地出现的野鸭（Anas platyrhynchos）的迁徙策略。我们的研究表明，野鸭是自然界中禽流感病毒（AIV）的主要宿主，其迁徙策略对病毒基因流动的贡献不同。居留（9.6%）、中距离（9.6%）和长距离（7.4%）迁徙的野鸭之间，AIV 的流行率没有差异。三组之间的病毒多样性也相当，这可能是由于鸟类在冬季聚集在湿地时，病毒池混合所致。然而，迁徙和居留的野鸭对越冬湿地的病毒基因库的贡献不同。迁徙的野鸭将病毒从北部繁殖地（阿拉斯加和西北太平洋沿岸）引入越冬种群，促进了大陆范围内的基因流动，但输入的病毒传播似乎受到限制。相比之下，居留的野鸭充当了 AIV 的储存库，促进了低纬度地区有限亚型（如 H5N2）的全年循环。本研究支持了一种病毒交换模型，即在温带地区，来自不同地理起源和暴露史的野生鸟类的汇聚驱动了病毒的交换。
