Norwegian Veterinary Institute, P.O. Box 64, NO-1432 Ås, Norway.
BirdLife Norway, Sandgata 30 B, NO-7012 Trondheim, Norway.
J Gen Virol. 2024 Nov;105(11). doi: 10.1099/jgv.0.002035.
Highly pathogenic avian influenza (HPAI) poses a substantial threat to several raptors. Between 2021 and 2023, HPAI viruses (HPAIVs) of the Goose/Guangdong lineage H5 clade 2.3.4.4b became widespread in wild birds in Norway, and H5N1 and H5N5 viruses were detected in 31 white-tailed eagles (, WTEs). Post-mortem examinations of four WTEs revealed no macroscopic pathological findings. Microscopic examinations showed the presence of myocardial and splenic necroses and a few lesions in the brain. hybridization revealed the presence of the virus in several organs, suggesting a multisystemic infection. The detection of HPAIV H5N5 in a WTE in February 2022 marked the first recorded occurrence of this subtype in Norway. Since then, the virus has persisted, sporadically being detected in WTEs and other wild bird species. Phylogenetic analyses reveal that at least two distinct incursions of HPAIV H5N1 Eurasian (EA) genotype C affected WTEs, likely introduced by migratory birds from Eurasia and seabirds entering from Western and Central Europe. Some WTE isolates from 2021 to 2022 clustered with those from Canada and Ireland, aligning with the transatlantic spread of H5N1. Others were related to the 2021 mass mortality of great skuas in the UK or outbreaks in seabird populations, including gannets, gulls and terns, during 2022 in the North Sea region. This suggests that the WTEs were likely preying on the affected birds. Our study highlights that WTEs can act as sentinels for some HPAIV strains, but the absence of several known circulating genotypes in WTEs suggests varying pathogenic effects on this species.
高致病性禽流感(HPAI)对许多猛禽构成了重大威胁。在 2021 年至 2023 年期间,挪威野生鸟类中广泛传播了鹅/广东谱系 H5 分支 2.3.4.4b 的 HPAIVs(HPAIVs),并且在 31 只白尾鹰(,WTEs)中检测到了 H5N1 和 H5N5 病毒。对四只 WTE 的尸体检查未发现明显的病理发现。显微镜检查显示心肌和脾脏坏死以及大脑中存在少数病变。杂交检测显示几种器官中存在该病毒,表明存在全身性感染。2022 年 2 月在一只 WTE 中检测到 HPAIV H5N5 标志着该亚型在挪威的首次记录发生。自那时以来,该病毒一直持续存在,偶尔在 WTE 和其他野生鸟类中检测到。系统发育分析表明,至少有两次不同的 HPAIV H5N1 欧亚(EA)基因型 C 入侵影响了 WTE,可能是由来自欧亚大陆的候鸟和从西欧和中欧进入的海鸟引入的。2021 年至 2022 年的一些 WTE 分离株与来自加拿大和爱尔兰的分离株聚类,与 H5N1 的跨大西洋传播一致。其他与 2021 年英国大贼鸥大量死亡或 2022 年北海地区海鸟种群(包括塘鹅、海鸥和燕鸥)爆发有关。这表明 WTE 可能以受感染的鸟类为食。我们的研究表明,WTE 可以作为某些 HPAIV 株的哨兵,但在 WTE 中未发现几种已知的循环基因型表明该物种的致病作用不同。