Abstract：
Mallards (Anas platyrhynchos) are an abundant anseriform migratory wild bird species worldwide and an important reservoir for the maintenance of low pathogenicity (LP) avian influenza viruses (AIV). They have also been implicated in the spread of high pathogenicity (HP) AIV after spill-over events from HPAIV-infected poultry. The spread of HPAIV within wild water bird populations may lead to viral contamination of natural habitats. The role of small shallow water bodies as a transmission medium of AIV among mallards is investigated here in three experimental settings. (i) Delayed onset but rapid progression of infection seeded by two mallards inoculated with either LP or HP AIV to each eight sentinel mallards was observed in groups with access to a small 100 L water pool. In contrast, groups with a bell drinker as the sole source of drinking water showed a rapid onset but lengthened course of infection. (ii) HPAIV infection also set off when virus was dispersed in the water pool; titres as low as 102 TCID50 L-1 (translating to 0.1 TCID50 mL-1) proved to be sufficient. (iii) Substantial loads of viral RNA (and infectivity) were also found on the surface of the birds\' breast plumage. \"Unloading\" of virus infectivity from contaminated plumage into water bodies may be an efficient mechanism of virus spread by infected mallards. However, transposure of HPAIV via the plumage of an uninfected mallard failed. We conclude, surface water in small shallow water bodies may play an important role as a mediator of AIV infection of aquatic wild birds.
摘要：
野鸭（Anasplatyrhynchos）是世界范围内丰富的一种迁徙野生鸟类，是维持低致病性（LP）禽流感病毒（AIV）的重要水库。它们还与感染HPAIV的家禽溢出事件后高致病性（HP）AIV的传播有关。HPAIV在野生水鸟种群中的传播可能导致自然栖息地的病毒污染。在三个实验环境中，研究了小浅水体作为野鸭中AIV传播介质的作用。（i）在进入100升小型水池的组中，观察到由接种了LP或HPAIV的两只野鸭接种的每八只前哨野鸭的感染延迟发作但迅速发展。相比之下,以钟饮者为唯一饮用水源的组显示出快速发作但延长的感染过程。（ii）当病毒分散在水池中时，HPAIV感染也会引起；滴度低至102TCID50L-1（翻译成0.1TCID50mL-1）被证明是足够的。（iii）在鸟类胸羽的表面也发现了大量的病毒RNA（和感染性）。将受污染的羽毛中的病毒感染性“卸载”到水体中可能是受感染的野鸭传播病毒的有效机制。然而,通过未感染的野鸭的羽毛进行HPAIV的暴露失败。我们得出结论，浅水小水体中的地表水可能是水生野生鸟类AIV感染的重要媒介。
