Zhai Boyu, Liu Lanlan, Li Xiang, Lv Xinru, Wu Jinyan, Li Jing, Lin Shengze, Yin Yuxiang, Lan Jiaqi, Du Jianan, Wu Chenwei, Wen Yi, Wang Yajun, Wang Yulong, Hou Zhijun, Li Yanbing, Chai Hongliang, Zeng Xiangwei
State Forestry Administration Key Laboratory of Wildlife Conservation, College of Wildlife and Protected Area, Northeast Forestry University, Harbin, China.
College of Basic Medical Science, Heilongjiang University of Chinese Medicine, Harbin, China.
Front Microbiol. 2022 Mar 1;13:842721. doi: 10.3389/fmicb.2022.842721. eCollection 2022.
In recent years, the emerging highly pathogenic avian influenza (HPAI) A(H5N8) virus has been reported with features of widely spread, an expanding host range, and cross-species transmission, attracting wide attention. The domestic duck plays a major role in the epidemiological cycle of the HPAI H5N8 virus, but little is known concerning innate immune responses during influenza infection in duck species. In this study, we used two wild-bird-origin viruses, H5N8 and H4N6, to conduct duck infection experiments, and detect the load of the two viruses, and retinoic acid-inducible gene I (RIG-I) and interferon β (IFN-β) in the host's natural immune response. Through comparison, it is found that the expression levels of RIG-I and IFN-β are both fluctuating. The innate immunity starts rapidly within 6 h after infection and is inhibited by the virus to varying degrees. The expression of RIG-I and IFN-β decreased on 1-2 days post-infection (dpi). The HPAI H5N8 virus has a stronger inhibitory effect on RIG-I than the low pathogenic avian influenza (LPAI) H4N6 virus and is the strongest in the lungs. After infection with HPAI H5N8 virus, 2 dpi, viral RNA replicates in large amounts in the lungs. It has been proven that RIG-I and IFN-β play an important role in the innate immune response of ducks to HPAI H5N8 virus infection, especially in the lungs. The main battlefield of RIG-I and IFN-β after infection with the LPAI H4N6 virus is in the rectum. Both viruses have been effectively controlled after 7 dpi. These results will help to understand the transmission mechanisms of avian influenza virus in wild ducks and help effectively prevent and control avian influenza.
近年来，新兴的高致病性禽流感（HPAI）A（H5N8）病毒被报道具有广泛传播、宿主范围不断扩大和跨物种传播的特征，引起了广泛关注。家鸭在HPAI H5N8病毒的流行病学循环中起主要作用，但关于鸭种流感感染期间的先天免疫反应知之甚少。在本研究中，我们使用两种源自野生鸟类的病毒H5N8和H4N6进行鸭感染实验，检测两种病毒的载量以及宿主天然免疫反应中的视黄酸诱导基因I（RIG-I）和干扰素β（IFN-β）。通过比较发现，RIG-I和IFN-β的表达水平均有波动。先天免疫在感染后6小时内迅速启动，并受到病毒不同程度的抑制。感染后1-2天（dpi），RIG-I和IFN-β的表达下降。HPAI H5N8病毒对RIG-I的抑制作用比低致病性禽流感（LPAI）H4N6病毒更强，在肺部最为明显。感染HPAI H5N8病毒后，2 dpi时，病毒RNA在肺部大量复制。已证明RIG-I和IFN-β在鸭对HPAI H5N8病毒感染的先天免疫反应中起重要作用，尤其是在肺部。感染LPAI H4N6病毒后，RIG-I和IFN-β的主要战场在直肠。两种病毒在7 dpi后均得到有效控制。这些结果将有助于了解禽流感病毒在野鸭中的传播机制，并有助于有效预防和控制禽流感。
