Novel Reassortant Human-Like H3N2 and H3N1 Influenza A Viruses Detected in Pigs Are Virulent and Antigenically Distinct from Swine Viruses Endemic to the United States
Novel Reassortant Human-Like H3N2 and H3N1 Influenza A Viruses Detected in Pigs Are Virulent and Antigenically Distinct from Swine Viruses Endemic to the United States
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DOI：
10.1128/jvi.01675-15
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发表时间：
2015-11-01
影响因子：
5.4
通讯作者：
Vincent, Amy L.
中科院分区：
文献类型：
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作者：
Rajao, Daniela S.;Gauger, Phillip C.;Vincent, Amy L.
美国农业部监测系统检测到人样猪H3甲型流感病毒（IAV）。我们鉴定了两种新型猪类H3 N2和H3 N1病毒，其血凝素（HA）基因与人类季节性H3毒株相似，内部基因与2009年H1N1大流行病毒密切相关。H3 N2神经氨酸酶（NA）是当代人类N2谱系，而H3 N1 NA是经典的猪N1谱系。这两种病毒在抗原性上都与在美国流行的猪H3病毒和猪疫苗株相距甚远，并且也显示出与人类季节性H3 N2病毒的抗原性漂移。它们在猪中的致病性和传播与具有共同HA祖先的人H3 N2病毒进行了比较。这两种猪类H3病毒都能有效地感染猪并传播给间接接触者，而人H3 N2病毒的感染效率要低得多。为了评估来自猪分离株的基因在其发病机制中的作用，在猪中测试了猪类人H3 N1病毒和季节性人H3 N2病毒之间的反向遗传产生的重组子。基因片段对毒力的贡献是复杂的，猪HA和内部基因在体内显示出效果。实验感染表明，这些新的H3病毒是有毒的，并可以持续向前传播的猪，和HA中的天然发生的突变与抗原的分歧从H3 IAV从人类和猪。因此，如果这些病毒引起更广泛的爆发，可能会对养猪业产生重大影响，这些新出现的猪IAV对人类的潜在风险应予以考虑。重要提示猪是甲型流感病毒（IAV）进化的重要宿主。IAV的人-猪传播导致了含有人源基因的重组病毒在猪中的传播，极大地促进了IAV在全球猪中的多样性。美国农业部监测系统最近发现了含有人和猪基因片段混合的新的类人H3 N2和H3 N1病毒。类似人类的病毒有效地感染了猪，并导致了空气传播，这可能是由于人类和猪H3病毒之间发现的多种变化。类似人类的猪病毒与当代美国H3猪病毒和猪疫苗中使用的毒株不同，由于缺乏群体免疫力，这些毒株可能对养猪业产生重大影响。此外，公共卫生专家应考虑适当评估这些新出现的猪H3病毒对人类的风险。
Human-like swine H3 influenza A viruses (IAV) were detected by the USDA surveillance system. We characterized two novel swine human-like H3N2 and H3N1 viruses with hemagglutinin (HA) genes similar to those in human seasonal H3 strains and internal genes closely related to those of 2009 H1N1 pandemic viruses. The H3N2 neuraminidase (NA) was of the contemporary human N2 lineage, while the H3N1 NA was of the classical swine N1 lineage. Both viruses were antigenically distant from swine H3 viruses that circulate in the United States and from swine vaccine strains and also showed antigenic drift from human seasonal H3N2 viruses. Their pathogenicity and transmission in pigs were compared to those of a human H3N2 virus with a common HA ancestry. Both swine human-like H3 viruses efficiently infected pigs and were transmitted to indirect contacts, whereas the human H3N2 virus did so much less efficiently. To evaluate the role of genes from the swine isolates in their pathogenesis, reverse genetics-generated reassortants between the swine human-like H3N1 virus and the seasonal human H3N2 virus were tested in pigs. The contribution of the gene segments to virulence was complex, with the swine HA and internal genes showing effects in vivo. The experimental infections indicate that these novel H3 viruses are virulent and can sustain onward transmission in pigs, and the naturally occurring mutations in the HA were associated with antigenic divergence from H3 IAV from humans and swine. Consequently, these viruses could have a significant impact on the swine industry if they were to cause more widespread outbreaks, and the potential risk of these emerging swine IAV to humans should be considered.IMPORTANCEPigs are important hosts in the evolution of influenza A viruses (IAV). Human-to-swine transmissions of IAV have resulted in the circulation of reassortant viruses containing human-origin genes in pigs, greatly contributing to the diversity of IAV in swine worldwide. New human-like H3N2 and H3N1 viruses that contain a mix of human and swine gene segments were recently detected by the USDA surveillance system. The human-like viruses efficiently infected pigs and resulted in onward airborne transmission, likely due to the multiple changes identified between human and swine H3 viruses. The human-like swine viruses are distinct from contemporary U.S. H3 swine viruses and from the strains used in swine vaccines, which could have a significant impact on the swine industry due to a lack of population immunity. Additionally, public health experts should consider an appropriate assessment of the risk of these emerging swine H3 viruses for the human population.