Ducks usually show little or no clinical signs following highly pathogenic avian influenza virus infection. In order to analyze whether the microbiota could contribute to the control of influenza virus replication in ducks, we used a broad-spectrum oral antibiotic treatment to deplete the microbiota before infection with a highly pathogenic H5N9 avian influenza virus. Antibiotic-treated ducks and nontreated control ducks did not show any clinical signs following H5N9 virus infection. We did not detect any significant difference in virus titers neither in the respiratory tract nor in the brain nor spleen. However, we found that antibiotic-treated H5N9 virus-infected ducks had significantly increased intestinal virus excretion at days 3 and 5 postinfection. This was associated with a significantly decreased antiviral immune response in the intestine of antibiotic-treated ducks. Our findings highlight the importance of an intact microbiota for an efficient control of avian influenza virus replication in ducks.IMPORTANCE Ducks are frequently infected with avian influenza viruses belonging to multiple subtypes. They represent an important reservoir species of avian influenza viruses, which can occasionally be transmitted to other bird species or mammals, including humans. Ducks thus have a central role in the epidemiology of influenza virus infection. Importantly, ducks usually show little or no clinical signs even following infection with a highly pathogenic avian influenza virus. We provide evidence that the microbiota contributes to the control of influenza virus replication in ducks by modulating the antiviral immune response. Ducks are able to control influenza virus replication more efficiently when they have an intact intestinal microbiota. Therefore, maintaining a healthy microbiota by limiting perturbations to its composition should contribute to the prevention of avian influenza virus spread from the duck reservoir.

中文翻译：

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微生物群有助于控制鸭中的高致病性H5N9流感病毒复制。

鸭通常在高致病性禽流感病毒感染后几乎没有临床症状。为了分析微生物群是否有助于控制鸭子中的流感病毒复制，我们在感染高致病性H5N9禽流感病毒之前使用了广谱口服抗生素治疗来消耗微生物群。H5N9病毒感染后，经抗生素处理的鸭子和未经处理的对照鸭子没有显示任何临床体征。我们在呼吸道，大脑和脾脏中均未发现病毒滴度有任何显着差异。但是，我们发现在感染后第3天和第5天，用抗生素治疗过的H5N9病毒感染的鸭的肠道病毒排泄量显着增加。这与经抗生素处理的鸭子的肠道中抗病毒免疫反应显着降低有关。我们的发现凸显了完整的微生物群对于有效控制鸭子中禽流感病毒复制的重要性。重要信息鸭子经常感染属于多种亚型的禽流感病毒。它们代表重要的禽流感病毒库，有时可传播给其他鸟类或哺乳动物，包括人。因此，鸭子在流感病毒感染的流行病学中具有核心作用。重要的是，即使在被高致病性禽流感病毒感染后，鸭子通常也很少或没有临床症状。我们提供的证据表明，微生物群通过调节抗病毒免疫应答，有助于控制鸭流感病毒的复制。鸭子具有完整的肠道菌群时，能够更有效地控制流感病毒的复制。因此，通过限制对其组成的干扰来维持健康的微生物群，应有助于预防从鸭水库传播的禽流感病毒。