Nguyen Anh Thi Viet, Hoang Vui Thi, Sung Haan Woo, Yeo Seon-Ju, Park Hyun
Zoonosis Research Center, Department of Infection Biology, School of Medicine, Wonkwang University, Iksan 54538, Korea.
College of Veterinary Medicine, Kangwon National University, Chuncheon 24341, Korea.
Viruses. 2021 Oct 30;13(11):2192. doi: 10.3390/v13112192.
The outbreaks of H5N2 avian influenza viruses have occasionally caused the death of thousands of birds in poultry farms. Surveillance during the 2018 winter season in South Korea revealed three H5N2 isolates in feces samples collected from wild birds (KNU18-28: A/Wild duck/South Korea/KNU18-28/2018, KNU18-86: A/Bean Goose/South Korea/KNU18-86/2018, and KNU18-93: A/Wild duck/South Korea/KNU18-93/2018). Phylogenetic tree analysis revealed that these viruses arose from reassortment events among various virus subtypes circulating in South Korea and other countries in the East Asia-Australasian Flyway. The NS gene of the KNU18-28 and KNU18-86 isolates was closely related to that of China's H10N3 strain, whereas the KNU18-93 strain originated from the H12N2 strain in Japan, showing two different reassortment events and different from a low pathogenic H5N3 (KNU18-91) virus which was isolated at the same day and same place with KNU18-86 and KNU18-93. These H5N2 isolates were characterized as low pathogenic avian influenza viruses. However, many amino acid changes in eight gene segments were identified to enhance polymerase activity and increase adaptation and virulence in mice and mammals. Experiments reveal that viral replication in MDCK cells was quite high after 12 hpi, showing the ability to replicate in mouse lungs. The hematoxylin and eosin-stained (H&E) lung sections indicated different degrees of pathogenicity of the three H5N2 isolates in mice compared with that of the control H1N1 strain. The continuing circulation of these H5N2 viruses may represent a potential threat to mammals and humans. Our findings highlight the need for intensive surveillance of avian influenza virus circulation in South Korea to prevent the risks posed by these reassortment viruses to animal and public health.
H5N2禽流感病毒的爆发偶尔会导致家禽养殖场成千上万只禽类死亡。2018年冬季在韩国进行的监测显示，从野生鸟类粪便样本中分离出三株H5N2病毒（KNU18-28：A/野鸭/韩国/KNU18-28/2018，KNU18-86：A/豆雁/韩国/KNU18-86/2018，以及KNU18-93：A/野鸭/韩国/KNU18-93/2018）。系统发育树分析表明，这些病毒源自韩国及东亚-澳大拉西亚飞行路线其他国家流行的各种病毒亚型之间的重配事件。KNU18-28和KNU18-86分离株的NS基因与中国的H10N3毒株密切相关，而KNU18-93毒株源自日本的H12N2毒株，显示出两种不同的重配事件，且不同于与KNU18-86和KNU18-93在同一天、同一地点分离出的低致病性H5N3（KNU18-91）病毒。这些H5N2分离株被鉴定为低致病性禽流感病毒。然而，在八个基因片段中发现了许多氨基酸变化，以增强聚合酶活性，并增加在小鼠和哺乳动物中的适应性及毒力。实验表明，感染后12小时，MDCK细胞中的病毒复制相当高，显示出在小鼠肺部复制的能力。苏木精和伊红染色（H&E）的肺切片表明，与对照H1N1毒株相比，三种H5N2分离株在小鼠中的致病性程度不同。这些H5N2病毒的持续传播可能对哺乳动物和人类构成潜在威胁。我们的研究结果强调，有必要对韩国禽流感病毒的传播进行强化监测，以预防这些重配病毒对动物和公共卫生造成的风险。
