Virology Department, Animal and Plant Health Agency, Addlestone, Surrey, United Kingdom.
WOAH/FAO International Reference Laboratory for Avian Influenza, Swine Influenza and Newcastle Disease, Animal and Plant Health Agency (APHA-Weybridge), Addlestone, Surrey, United Kingdom.
Microbiol Spectr. 2023 Aug 17;11(4):e0477622. doi: 10.1128/spectrum.04776-22. Epub 2023 Jun 26.
Since 2020, the United Kingdom and Europe have experienced annual epizootics of high-pathogenicity avian influenza virus (HPAIV). The first epizootic, during the autumn/winter of 2020-2021, involved six H5Nx subtypes, although H5N8 HPAIV dominated in the United Kingdom. While genetic assessments of the H5N8 HPAIVs within the United Kingdom demonstrated relative homogeneity, there was a background of other genotypes circulating at a lower degree with different neuraminidase and internal genes. Following a small number of detections of H5N1 in wild birds over the summer of 2021, the autumn/winter of 2021-2022 saw another European H5 HPAIV epizootic that dwarfed the prior epizootic. This second epizootic was dominated almost exclusively by H5N1 HPAIV, although six distinct genotypes were defined. We have used genetic analysis to evaluate the emergence of different genotypes and proposed reassortment events that have been observed. The existing data suggest that the H5N1 viruses circulating in Europe during late 2020 continued to circulate in wild birds throughout 2021, with minimal adaptation, but then went on to reassort with AIVs in the wild bird population. We have undertaken an in-depth genetic assessment of H5 HPAIVs detected in the United Kingdom over two winter seasons and demonstrate the utility of in-depth genetic analyses in defining the diversity of H5 HPAIVs circulating in avian species, the potential for zoonotic risk, and whether incidents of lateral spread can be defined over independent incursions of infections from wild birds. This provides key supporting data for mitigation activities. High-pathogenicity avian influenza virus (HPAIV) outbreaks devastate avian species across all sectors, having both economic and ecological impacts through mortalities in poultry and wild birds, respectively. These viruses can also represent a significant zoonotic risk. Since 2020, the United Kingdom has experienced two successive outbreaks of H5 HPAIV. While H5N8 HPAIV was predominant during the 2020-2021 outbreak, other H5 subtypes were also detected. The following year, there was a shift in the subtype dominance to H5N1 HPAIV, but multiple H5N1 genotypes were detected. Through the thorough utilization of whole-genome sequencing, it was possible to track and characterize the genetic evolution of these H5 HPAIVs in United Kingdom poultry and wild birds. This enabled us to assess the risk posed by these viruses at the poultry-wild bird and the avian-human interfaces and to investigate the potential lateral spread between infected premises, a key factor in understanding the threat to the commercial sector.
自 2020 年以来，英国和欧洲经历了高致病性禽流感病毒（HPAIV）的年度流行。第一次流行发生在 2020-2021 年的秋冬季节，涉及六种 H5Nx 亚型，尽管 H5N8 HPAIV 在英国占主导地位。尽管对英国 H5N8 HPAIV 的遗传评估表明相对同质，但仍有其他基因型以较低程度传播，具有不同的神经氨酸酶和内部基因。在 2021 年夏季野生鸟类中发现少量 H5N1 后，2021-2022 年的秋冬季节又发生了另一次欧洲 H5 HPAIV 流行，规模超过了之前的流行。这次第二次流行几乎完全由 H5N1 HPAIV 主导，尽管定义了六种不同的基因型。我们使用遗传分析评估了不同基因型的出现，并提出了观察到的重组事件。现有数据表明，2020 年末在欧洲循环的 H5N1 病毒在 2021 年继续在野生鸟类中循环，适应性极小，但随后与野生鸟类中的禽 AIV 重组。我们对英国两个冬季季节检测到的 H5 HPAIV 进行了深入的遗传评估，并证明了深入遗传分析在定义循环在禽种中的 H5 HPAIV 多样性、人畜共患病风险的潜力以及是否可以定义独立入侵的侧向传播方面的实用性来自野生鸟类的感染。这为缓解活动提供了关键的支持数据。高致病性禽流感病毒（HPAIV）爆发使所有部门的禽类物种遭受重创，分别通过家禽和野生鸟类的死亡对经济和生态造成影响。这些病毒也可能构成重大的人畜共患病风险。自 2020 年以来，英国经历了两次连续的 H5 HPAIV 爆发。虽然 2020-2021 年爆发期间 H5N8 HPAIV 占主导地位，但也检测到了其他 H5 亚型。次年，H5N1 HPAIV 的亚型优势发生转变，但检测到多种 H5N1 基因型。通过充分利用全基因组测序，我们能够跟踪和描述这些 H5 HPAIV 在英国家禽和野生鸟类中的遗传进化。这使我们能够评估这些病毒在禽-野鸟和禽-人界面造成的风险，并调查受感染场所之间的潜在侧向传播，这是了解对商业部门威胁的关键因素。
