Department of Viroscience, Erasmus MC, P.O. Box 2040, 3000 CA, Rotterdam, The Netherlands.
Department of Pathobiology, Faculty of Veterinary Medicine, Utrecht University, Postbus 80163, 3508 TD, Utrecht, The Netherlands.
Emerg Microbes Infect. 2018 Apr 18;7(1):67. doi: 10.1038/s41426-018-0070-9.
Highly pathogenic avian influenza (HPAI) is essentially a poultry disease. Wild birds have traditionally not been involved in its spread, but the epidemiology of HPAI has changed in recent years. After its emergence in southeastern Asia in 1996, H5 HPAI virus of the Goose/Guangdong lineage has evolved into several sub-lineages, some of which have spread over thousands of kilometers via long-distance migration of wild waterbirds. In order to determine whether the virus is adapting to wild waterbirds, we experimentally inoculated the HPAI H5N8 virus clade 2.3.4.4 group A from 2014 into four key waterbird species-Eurasian wigeon (Anas penelope), common teal (Anas crecca), mallard (Anas platyrhynchos), and common pochard (Aythya ferina)-and compared virus excretion and disease severity with historical data of the HPAI H5N1 virus infection from 2005 in the same four species. Our results showed that excretion was highest in Eurasian wigeons for the 2014 virus, whereas excretion was highest in common pochards and mallards for the 2005 virus. The 2014 virus infection was subclinical in all four waterbird species, while the 2005 virus caused clinical disease and pathological changes in over 50% of the common pochards. In chickens, the 2014 virus infection caused systemic disease and high mortality, similar to the 2005 virus. In conclusion, the evidence was strongest for Eurasian wigeons as long-distance vectors for HPAI H5N8 virus from 2014. The implications of the switch in species-specific virus excretion and decreased disease severity may be that the HPAI H5 virus more easily spreads in the wild-waterbird population.
高致病性禽流感（HPAI）本质上是一种家禽疾病。野生鸟类传统上不参与其传播，但近年来 HPAI 的流行病学发生了变化。1996 年在东南亚出现后，广东鹅源 H5 HPAI 病毒进化成了几个亚系，其中一些通过野生水鸟的长途迁徙传播了数千公里。为了确定该病毒是否在适应野生水鸟，我们实验性地将 2014 年的 HPAI H5N8 病毒 2.3.4.4 分支 A 接种到 4 种关键水鸟物种——欧亚泽凫（Anas penelope）、普通绿头鸭（Anas crecca）、绿头鸭（Anas platyrhynchos）和普通秋沙鸭（Aythya ferina）——并将其与 2005 年同一 4 种物种中 HPAI H5N1 病毒感染的历史数据进行了比较。结果显示，2014 年病毒在欧亚泽凫中的排泄量最高，而 2005 年病毒在普通秋沙鸭和绿头鸭中的排泄量最高。2014 年病毒感染在所有 4 种水鸟中均呈亚临床症状，而 2005 年病毒感染导致超过 50%的普通秋沙鸭出现临床疾病和病理变化。在鸡中，2014 年病毒感染引起全身性疾病和高死亡率，与 2005 年病毒相似。综上所述，欧亚泽凫是 2014 年 HPAI H5N8 病毒的长距离传播载体的证据最为充分。物种特异性病毒排泄和疾病严重程度降低的意义可能是 HPAI H5 病毒更容易在野生水鸟种群中传播。
