Spackman Erica, Prosser Diann J, Pantin-Jackwood Mary J, Berlin Alicia M, Stephens Christopher B
1 Southeast Poultry Research Laboratory, US National Poultry Research Center, US Department of Agriculture-Agricultural Research Service, 934 College Station Road, Athens, Georgia 30605, USA.
2 Patuxent Wildlife Research Center, US Geological Survey, Beltsville Lab, 10300 Baltimore Avenue, Beltsville, Maryland 20705, USA.
J Wildl Dis. 2017 Oct;53(4):832-842. doi: 10.7589/2017-01-003. Epub 2017 May 17.
Waterfowl are the natural hosts of avian influenza virus (AIV) and disseminate the virus worldwide through migration. Historically, surveillance and research efforts for AIV in waterfowl have focused on dabbling ducks. The role of diving ducks in AIV ecology has not been well characterized. In this study, we examined the relative susceptibility and pathogenicity of clade 2.3.4.4 H5 highly pathogenic AIV (HPAIV) in two species of diving ducks. Juvenile and adult Ruddy Duck (Oxyura jamaicensis) and juvenile Lesser Scaup (Aythya affinis) were intranasally inoculated with A/Northern Pintail/WA/40964/2014 H5N2 HPAIV. Additional groups of juvenile Lesser Scaups were inoculated with A/Gyrfalcon/WA/41088/2014 H5N8 HPAIV. The approximate 50% bird infectious doses (BID) of the H5N2 isolate for adult Ruddy Ducks was <10 50% egg infectious doses (EID) and for the juvenile Lesser Scaups it was <10 EID. There were insufficient juvenile Ruddy Ducks to calculate the BID. The BID for the juvenile Lesser Scaups inoculated with the H5N8 isolate was 10 EID. Clinical disease was not observed in any group; however, mortality occurred in the juvenile Ruddy Ducks inoculated with the H5N2 virus (three of five ducks), and staining for AIV antigen was observed in numerous tissues from these ducks. One adult Ruddy Duck also died and although it was infected with AIV (the duck was positive for virus shedding and AIV antigen was detected in tissues), it was also infected with coccidiosis. The proportion of ducks shedding virus was related to the dose administered, but the titers were similar among dose groups. The group with the fewest ducks shedding virus was the adult Ruddy Ducks. There was a trend for the Lesser Scaups to shed higher titers of virus than the Ruddy Ducks. No virus shedding was detected after 7 d postinoculation in any group. Similar to dabbling ducks, Lesser Scaups and Ruddy Ducks are susceptible to infection with this H5 HPAIV lineage, although they excrete lower titers of virus.
水禽是禽流感病毒（AIV）的天然宿主，并通过迁徙将病毒传播至全球。从历史上看，针对水禽中AIV的监测和研究工作主要集中在涉鸭类。潜鸭在AIV生态中的作用尚未得到充分描述。在本研究中，我们检测了2.3.4.4分支H5高致病性禽流感病毒（HPAIV）在两种潜鸭中的相对易感性和致病性。将幼年和成年赤颈鸭（Oxyura jamaicensis）以及幼年小潜鸭（Aythya affinis）经鼻接种A/北长尾鸭/华盛顿/40964/2014 H5N2 HPAIV。另外几组幼年小潜鸭接种了A/矛隼/华盛顿/4,1088/2014 H5N8 HPAIV。H5N2毒株对成年赤颈鸭的半数禽感染剂量（BID）约为<10 50% 鸡胚感染剂量（EID），对幼年小潜鸭则为<10 EID。幼年赤颈鸭数量不足，无法计算BID。接种H5N8毒株的幼年小潜鸭的BID为10 EID。任何组均未观察到临床疾病；然而，接种H5N2病毒的幼年赤颈鸭出现了死亡（5只鸭中有3只），并且在这些鸭的多个组织中观察到AIV抗原染色。1只成年赤颈鸭也死亡，尽管它感染了AIV（该鸭病毒排毒呈阳性且在组织中检测到AIV抗原），但它也感染了球虫病。排病毒鸭的比例与接种剂量有关，但各剂量组的滴度相似。排病毒鸭数量最少的组是成年赤颈鸭。小潜鸭排出病毒滴度有高于赤颈鸭的趋势。接种后7天，任何组均未检测到病毒排毒。与涉鸭类相似，小潜鸭和赤颈鸭对这种H5 HPAIV谱系易感，尽管它们排出的病毒滴度较低。
