Center for Diagnostics and Vaccine Development, Centers for Disease Control, No. 161, Kun-Yang Street, Taipei, 11561, Taiwan, ROC.
Department of Laboratory Medicine, Changhua Christian Hospital, Changhua, Taiwan, ROC.
Virol J. 2022 Apr 7;19(1):63. doi: 10.1186/s12985-022-01794-2.
Influenza A virus infections occur in different species, causing mild-to-severe symptoms that lead to a heavy disease burden. H1N1, H1N2 and H3N2 are major subtypes of swine influenza A viruses in pigs and occasionally infect humans.
A case infected by novel influenza virus was found through laboratory surveillance system for influenza viruses. Clinical specimens were tested by virus culture and/or real-time RT-PCR. The virus was identified and characterized by gene sequencing and phylogenetic analysis.
In 2021, for the first time in Taiwan, an influenza A(H1N2)v virus was isolated from a 5-year old girl who was suffering from fever, runny nose and cough. The isolated virus was designated A/Taiwan/1/2021(H1N2)v. Full-genome sequencing and phylogenetic analyses revealed that A/Taiwan/1/2021(H1N2)v is a novel reassortant virus containing hemagglutinin (HA) and neuraminidase (NA) gene segments derived from swine influenza A(H1N2) viruses that may have been circulating in Taiwan for decades, and the other 6 internal genes (PB2, PB2, PA, NP, M and NS) are from human A(H1N1)pdm09 viruses.
Notably, the HA and NA genes of A/Taiwan/1/2021(H1N2)v separately belong to specific clades that are unique for Taiwanese swine and were proposed to be introduced from humans in different time periods. Bidirectional transmission between humans and swine contributes to influenza virus diversity and poses the next pandemic threat.
甲型流感病毒在不同物种中引发感染，导致从轻症到重症的各种症状，从而造成沉重的疾病负担。H1N1、H1N2 和 H3N2 是猪流感 A 病毒的主要亚型，偶尔会感染人类。
通过流感病毒实验室监测系统发现了一例新型流感病毒感染病例。通过病毒培养和/或实时 RT-PCR 检测临床标本。通过基因测序和系统发育分析对病毒进行鉴定和特征分析。
2021 年，在台湾，首次从一名 5 岁女孩身上分离出甲型流感 A(H1N2)v 病毒，该女孩患有发热、流鼻涕和咳嗽。分离出的病毒被命名为 A/Taiwan/1/2021(H1N2)v。全基因组测序和系统发育分析显示，A/Taiwan/1/2021(H1N2)v 是一种新型重配病毒，含有血凝素 (HA) 和神经氨酸酶 (NA) 基因片段，源自可能在台湾流行数十年的猪流感 A(H1N2)病毒，其他 6 个内部基因（PB2、PB1、PA、NP、M 和 NS）来自人类 A(H1N1)pdm09 病毒。
值得注意的是，A/Taiwan/1/2021(H1N2)v 的 HA 和 NA 基因分别属于特定的分支，这些分支在台湾的猪中是独特的，据推测是在不同时期从人类引入的。人类和猪之间的双向传播促进了流感病毒的多样性，并构成了下一次大流行的威胁。
