Tanikawa Taichiro, Fujii Kotaro, Sugie Yuji, Tsunekuni Ryota, Nakayama Momoko, Kobayashi Sota
National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan.
Toyama Prefectural Tobu Livestock Hygiene Service Center, 46 Mizuhashi-kanao-shin, Toyama 939-3536, Japan.
Vet Microbiol. 2022 Sep;272:109496. doi: 10.1016/j.vetmic.2022.109496. Epub 2022 Jun 28.
The Goose/Guangdong-lineage (Gs/Gd) H5 high pathogenicity avian influenza viruses (HPAIVs) spread among poultry and wild birds worldwide; an association has been identified between the migration of wild birds and spread of HPAIVs. Every autumn-spring season, the mallard (Anas platyrhynchos) migrates to Japan in substantial numbers for overwintering; however, to the best of our knowledge, no virological studies have focused on mallards' susceptibility to the HPAIVs in Japan. To evaluate the susceptibility of mallards to infection with Gs/Gd H5 HPAIVs isolated during previous outbreaks in Japan, we experimentally infected the birds with various virus strains: A/chicken/Yamaguchi/7/2004 (H5N1) (clade 2.5), A/chicken/Miyazaki/K11/2007 (H5N1) (clade 2.2), A/whooper swan/Akita/1/2008 (H5N1) (clade 2.3.2), A/mandarin duck/Miyazaki/22M-765/2011 (H5N1) (clade 2.3.2.1c), A/duck/Chiba/26-372-48/2014 (H5N8) (clade 2.3.4.4c), A/duck/Hyogo/1/2016 (H5N6) (clade 2.3.4.4e) and A/mute swan/Shimane/3211A002/2017 (H5N6) (clade 2.3.4.4b). The birds exhibited high tracheal shedding for a prolonged period, particularly those infected with A/duck/Hyogo/1/2016 (H5N6). Various clinical manifestations ranging from asymptomatic to mild (corneal opacity) infections to neurological disorders accompanied by mortality were noted depending on the virus strain. Furthermore, virus-infected mallards contaminated both cohoused mallards and water in their surroundings. Thus, mallards may disseminate viruses in the environment, thereby influencing HPAI outbreaks in Japan. Therefore, mallards represent an important migratory bird species that spread HPAIVs in Japan.
鹅/广东谱系（Gs/Gd）H5高致病性禽流感病毒（HPAIVs）在全球范围内的家禽和野生鸟类中传播；野生鸟类的迁徙与HPAIVs的传播之间已被证实存在关联。每年春秋季节，绿头鸭（Anas platyrhynchos）大量迁徙至日本越冬；然而，据我们所知，在日本尚未有病毒学研究关注绿头鸭对HPAIVs的易感性。为评估绿头鸭对在日本以往疫情中分离出的Gs/Gd H5 HPAIVs感染的易感性，我们用多种病毒株对这些鸟类进行了实验性感染：A/鸡/山口/7/2004（H5N1）（2.5分支）、A/鸡/宫崎/K11/2007（H5N1）（2.2分支）、A/疣鼻天鹅/秋田/1/2008（H5N1）（2.3.2分支）、A/鸳鸯/宫崎/22M - 765/2011（H5N1）（2.3.2.1c分支）、A/鸭/千叶/26 - 372 - 48/2014（H5N8）（2.3.4.4c分支）、A/鸭/兵库/1/2016（H5N6）（2.3.4.4e分支）以及A/疣鼻天鹅/岛根/3211A002/2017（H5N6）（2.3.4.4b分支）。这些鸟类在较长时间内气管排毒量高，尤其是感染A/鸭/兵库/1/2016（H5N6）的鸟类。根据病毒株的不同，观察到了从无症状到轻度（角膜混浊）感染再到伴有死亡的神经紊乱等各种临床表现。此外，感染病毒的绿头鸭污染了同笼饲养的绿头鸭及其周围的水。因此，绿头鸭可能在环境中传播病毒，从而影响日本的高致病性禽流感疫情爆发。所以，绿头鸭是在日本传播HPAIVs的一种重要候鸟物种。
