Genotypic evolution and antigenic drift of H9N2 influenza viruses in China from 1994 to 2008

Sun, Yipeng; Pu, Juan; Jiang, Zhan-Lei; Guan, Tao; Xia, Yingju; Xu, Qi; Liu, Linqing; Ma, Ben; Tian, Fei; Brown, Earl G.; Liu, Jinhua

doi:10.1016/j.vetmic.2010.05.010

Cited by 141 publications

(150 citation statements)

References 30 publications

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“…Phylogenetic trees were automatically partitioned into clusters (24) using a 20th percentile cutoff. Clades were then manually merged, if necessary, based on the branching posterior and reported classification (19,20,25). In each tree of eight segments, most of the 2010-2013 viruses belonged to the same clade ( Fig.…”

Section: Significancementioning

confidence: 99%

“…Antigenic drift, induced mainly in the HA glycoprotein, can decrease a vaccine's efficacy and cause outbreaks of viral infection (21)(22)(23)28). Phylogenetic analysis revealed that the 2010-2013 H9N2 viruses were mainly in clade 6 and clade 9, whereas the vaccine strains were in clade 2 ( from different antigenic groups were included (20), as were two representative vaccine strains as controls (Ck/SD/6/96 and Ck/SH/ F/98; Table S2). The G57 viruses prevalent in 2010-2011, as well as some earlier viruses (mainly 2009), had lower HI titers eight or more times the HI titers of the vaccine strains in reactions with vaccine antisera.…”

Section: Significancementioning

confidence: 99%

“…These H9N2 vaccines initially limited the outbreaks and virus spread. However, despite multiple doses, the H9N2 vaccines became less effective, especially after 2007, and H9N2 influenza virus continues to circulate in vaccinated chicken flocks and has caused sporadic disease outbreaks (8,10,(12)(13)(14)(15)(16)(17)(18)(19)(20). However, the recent prevalence and molecular evolution of the H9N2 viruses in chickens especially in the flocks receiving large-scale vaccination, and their role in the emergence of human H7N9 virus, are not fully understood.…”

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confidence: 99%

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Evolution of the H9N2 influenza genotype that facilitated the genesis of the novel H7N9 virus

Wang

Yin

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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The emergence of human infection with a novel H7N9 influenza virus in China raises a pandemic concern. Chicken H9N2 viruses provided all six of the novel reassortant’s internal genes. However, it is not fully understood how the prevalence and evolution of these H9N2 chicken viruses facilitated the genesis of the novel H7N9 viruses. Here we show that over more than 10 y of cocirculation of multiple H9N2 genotypes, a genotype (G57) emerged that had changed antigenicity and improved adaptability in chickens. It became predominant in vaccinated farm chickens in China, caused widespread outbreaks in 2010–2013 before the H7N9 viruses emerged in humans, and finally provided all of their internal genes to the novel H7N9 viruses. The prevalence and variation of H9N2 influenza virus in farmed poultry could provide an important early warning of the emergence of novel reassortants with pandemic potential.

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Section: Significancementioning

confidence: 99%

Section: Significancementioning

confidence: 99%

mentioning

confidence: 99%

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Evolution of the H9N2 influenza genotype that facilitated the genesis of the novel H7N9 virus

Wang

Yin

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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308

340

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“…H9N2 influenza viruses have been widely reported to infect mammals, including pigs and humans (Abolnik et al, 2010;Butt et al, 2010;Cong et al, 2007;Sun et al, 2010;Xu et al, 2007); there is evidence that a large number of people have been infected with H9N2 viruses, in particular poultry workers (Coman et al, 2013;Jia et al, 2009;Wang et al, 2009). H9N2 virus infections in humans showed typical human flu-like symptoms, which can easily go undetected or unreported (Butt et al, 2005;Lin et al, 2000).…”

Section: Introductionmentioning

confidence: 99%

PA-X is a virulence factor in avian H9N2 influenza virus

Gao

Sun

et al. 2015

Journal of General Virology

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H9N2 influenza viruses have been circulating worldwide in multiple avian species, and regularly infect pigs and humans. Recently, a novel protein, PA-X, produced from the PA gene by ribosomal frameshifting, was demonstrated to be an antivirulence factor in pandemic 2009 H1N1, highly pathogenic avian H5N1 and 1918 H1N1 viruses. However, a similar role of PA-X in the prevalent H9N2 avian influenza viruses has not been established. In this study, we compared the virulence and cytopathogenicity of H9N2 WT virus and H9N2 PA-X-deficient virus. Loss of PA-X in H9N2 virus reduced apoptosis and had a marginal effect on progeny virus output in human pulmonary adenocarcinoma (A549) cells. Without PA-X, PA was less able to suppress co-expressed GFP in human embryonic kidney 293T cells. Furthermore, absence of PA-X in H9N2 virus attenuated viral pathogenicity in mice, which showed no mortality, reduced progeny virus production, mild-to-normal lung histopathology, and dampened proinflammatory cytokine and chemokine response. Therefore, unlike previously reported H1N1 and H5N1 viruses, we show that PA-X protein in H9N2 virus is a pro-virulence factor in facilitating viral pathogenicity and that the pro-or antivirulence role of PA-X in influenza viruses is virus strain-dependent.

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“…Members of the Eurasian lineage jumped into poultry in Asia in the late 1980s causing outbreaks. These outbreaks have occurred in land-based poultry in many countries including China, Iran, Pakistan, Lebanon, Israel and Egypt (Barbour et al, 2006;Davidson et al, 2014;Naeem et al, 1999;Nili & Asasi, 2003), and H9N2 viruses are currently endemic in poultry populations across much of Asia and the Middle East, mainly in chickens, quail and turkeys (Alexander, 2000;Guo et al, 2000;Naeem et al, 1999;Sun et al, 2010).…”

Section: Introductionmentioning

confidence: 99%

Replication and transmission of mammalian-adapted H9 subtype influenza virus in pigs and quail

Obadan

Kimble

Rajão

et al. 2015

Journal of General Virology

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Influenza A virus is a major pathogen of birds, swine and humans. Strains can jump between species in a process often requiring mutations and reassortment, resulting in outbreaks and, potentially, pandemics. H9N2 avian influenza is predominant in poultry across Asia and occasionally infects humans and swine. Pandemic H1N1 (H1N1pdm) is endemic in humans and swine and has a history of reassortment in pigs. Previous studies have shown the compatibility of H9N2 and H1N1pdm for reassortment in ferrets, a model for human infection and transmission. Here, the effects of ferret adaptation of H9 surface gene segments on the infectivity and transmission in at-risk natural hosts, specifically swine and quail, were analysed. Reassortant H9N1 and H9N2 viruses, carrying seven or six gene segments from H1N1pdm, showed infectivity and transmissibility in swine, unlike the wholly avian H9N2 virus with ferretadapted surface genes. In quail, only the reassortant H9N2 with the six internal gene segments from the H1N1pdm strain was able to infect and transmit, although less efficiently than the wholly avian H9N2 virus with ferret-adapted surface genes. These results highlight that ferretadapted mutations on the haemagglutinin of H9 subtype virus do not restrict the ability of the virus to infect swine and quail, and that the ability to transmit in these species depends on the context of the whole virus. As such, this study emphasizes the threat that H9N2 reassortant viruses pose to humans and agricultural species and the importance of the genetic constellation of the virus to its ability to replicate and transmit in natural hosts of influenza.

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Genotypic evolution and antigenic drift of H9N2 influenza viruses in China from 1994 to 2008

Cited by 141 publications

References 30 publications

Evolution of the H9N2 influenza genotype that facilitated the genesis of the novel H7N9 virus

Evolution of the H9N2 influenza genotype that facilitated the genesis of the novel H7N9 virus

PA-X is a virulence factor in avian H9N2 influenza virus

Replication and transmission of mammalian-adapted H9 subtype influenza virus in pigs and quail

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