Department of Veterinary and Animal Sciences, University of Copenhagen, 1870 Frederiksberg, Denmark.
Virus and Microbiological Special Diagnostics, Statens Serum Institut, 2300 Copenhagen S, Denmark.
Viruses. 2021 May 11;13(5):886. doi: 10.3390/v13050886.
Since late 2020, outbreaks of H5 highly pathogenic avian influenza (HPAI) viruses belonging to clade 2.3.4.4b have emerged in Europe. To investigate the evolutionary history of these viruses, we performed genetic characterization on the first HPAI viruses found in Denmark during the autumn of 2020. H5N8 viruses from 14 wild birds and poultry, as well as one H5N5 virus from a wild bird, were characterized by whole genome sequencing and phylogenetic analysis. The Danish H5N8 viruses were found to be genetically similar to each other and to contemporary European clade 2.3.4.4b H5N8 viruses, while the Danish H5N5 virus was shown to be a unique genotype from the H5N5 viruses that circulated at the same time in Russia, Germany, and Belgium. Genetic analyses of one of the H5N8 viruses revealed the presence of a substitution (PB2-M64T) that is highly conserved in human seasonal influenza A viruses. Our analyses showed that the late 2020 clade 2.3.4.4b HPAI H5N8 viruses were most likely new incursions introduced by migrating birds to overwintering sites in Europe, rather than the result of continued circulation of H5N8 viruses from previous introductions to Europe in 2016/2017 and early 2020.
自 2020 年末以来，属于 2.3.4.4b 分支的 H5 高致病性禽流感（HPAI）病毒在欧洲爆发。为了研究这些病毒的进化历史，我们对 2020 年秋季在丹麦首次发现的 HPAI 病毒进行了遗传特征分析。通过全基因组测序和系统进化分析，对来自 14 只野鸟和家禽的 H5N8 病毒以及一只野鸟的 H5N5 病毒进行了特征描述。丹麦的 H5N8 病毒彼此之间以及与当时欧洲的 2.3.4.4b 分支的 H5N8 病毒在遗传上相似，而丹麦的 H5N5 病毒与当时在俄罗斯、德国和比利时流行的 H5N5 病毒的基因型不同。对其中一种 H5N8 病毒的遗传分析显示存在一个（PB2-M64T）替换，该替换在人类季节性流感 A 病毒中高度保守。我们的分析表明，2020 年末的 2.3.4.4b 分支的 HPAI H5N8 病毒很可能是候鸟迁徙到欧洲越冬地的新传入，而不是 2016/2017 年和 2020 年初欧洲 H5N8 病毒持续传播的结果。
