Influenza H7N9 and H9N2 Viruses: Coexistence in Poultry Linked to Human H7N9 Infection and Genome Characteristics

Yu, Xinliang; Jin, Tao; Cui, Yu‐Jun; Pu, Xiaoying; Li, Jun; Xu, Jin; Liu, Guang; Jia, Huijue; Liú, Dan; Song, Siyuan; Yu, Yong; Xie, Li; Huang, Ren-Jie; Ding, Hua; Yu, Keming; Zhou, Yitong; Wang, Yayu; Xu, Xun; Yin, Ye; Wang, Jian; Guo, Changhong; Yang, Xianwei; Hu, Liangping; Wu, Xiaopeng; Wang, Hailong; Liu, Jun; Zhao, Guoliang; Zhou, Jiyong; Pan, Jinren; Gao, George F.; Yang, Ruifu; Wang, Jun

doi:10.1128/jvi.02059-13

Cited by 95 publications

(86 citation statements)

References 24 publications

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“…Reasonable explanations for these differences from our data might be based on the different application routes (oculo-oro-nasal versus intranasal/intratracheal) and different methods of measurement of viral excretion. Further data from experimental infections of chickens, as well as genuine samples (swabs sampled from different poultry species), from the affected region rather support our findings of substantial replication in and shedding by chickens (29,31,32).…”

Section: Discussionsupporting

confidence: 69%

Avian Influenza H7N9/13 and H7N7/13: a Comparative Virulence Study in Chickens, Pigeons, and Ferrets

Kalthoff

Bogs

Grund

et al. 2014

J Virol

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Human influenza cases caused by a novel avian H7N9 virus in China emphasize the zoonotic potential of that subtype. We compared the infectivity and pathogenicity of the novel H7N9 virus with those of a recent European avian H7N7 strain in chickens, pigeons, and ferrets. Neither virus induced signs of disease despite substantial replication in inoculated chickens and rapid transmission to contact chickens. Evidence of the replication of both viruses in pigeons, albeit at lower levels of RNA excretion, was also detected. No clear-cut differences between the two H7 isolates emerged regarding replication and antibody development in avian hosts. In ferrets, in contrast, greater replication of the avian H7N9 virus than of the H7N7 strain was observed with significant differences in viral presence, e.g., in nasal wash, lung, and cerebellum samples. Importantly, both viruses showed the potential to spread to the mammal brain. We conclude that efficient asymptomatic viral replication and shedding, as shown in chickens, facilitate the spread of H7 viruses that may harbor zoonotic potential. Biosafety measures are required for the handling of poultry infected with avian influenza viruses of the H7 subtype, independently of their pathogenicity for gallinaceous poultry. IMPORTANCEThis study is important to the field since it provides data about the behavior of the novel H7N9 avian influenza virus in chickens, pigeons, and ferrets in comparison with that of a recent low-pathogenicity H7N7 strain isolated from poultry. We clearly show that chickens, but not pigeons, are highly permissive hosts of both H7 viruses, allowing high-titer replication and virus shedding without any relevant clinical signs. In the ferret model, the potential of both viruses to infect mammals could be demonstrated, including infection of the brain. However, the replication efficiency of the H7N9 virus in ferrets was higher than that of the H7N7 strain. In conclusion, valuable data for the risk analysis of low-pathogenicity avian influenza viruses of the H7 subtype are provided that could also be used for the risk assessment of zoonotic potentials and necessary biosafety measures.

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Section: Discussionsupporting

confidence: 69%

Avian Influenza H7N9/13 and H7N7/13: a Comparative Virulence Study in Chickens, Pigeons, and Ferrets

Kalthoff

Bogs

Grund

et al. 2014

J Virol

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“…Moreover, our environmental surveillance data suggested that a higher ratio of H9N2 viruses had been detected in Guangdong LPM than in other regions of China (Table 1) (14). Since live poultry was the major source of H7N9 viruses (8,(15)(16)(17), the coexistence of H9N2 viruses in that susceptible population was likely to generate appropriate conditions for the emer- gence of novel reassortment variants (6). From this, we proposed that the A/Guangdong/1/2013 (H7N9) virus was most likely a product of the most recent reassortment between a novel H7N9 virus and the local H9N2 viruses.…”

Section: Discussionmentioning

confidence: 99%

“…According to the epidemiology and sequence analyses, H7N9 virus-contaminated live-poultry markets (LPM) are regarded as the major sources of the human infections with the H7N9 virus (6)(7)(8). Therefore, after the initial report of H7N9 influenza virus infection in humans in March 2013, environmental sampling programs and enhanced sentinel hospital surveillance were implemented in Guangdong in order to identify possible cases of infection and to analyze the evolution of the virus.…”

mentioning

confidence: 99%

Continuing Reassortment Leads to the Genetic Diversity of Influenza Virus H7N9 in Guangdong, China

Zeng

et al. 2014

J Virol

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On 30 March 2013, a novel avian influenza A H7N9 virus causing severe human respiratory infections was identified in China. Preliminary sequence analyses have shown that the virus is a reassortant of H7N9 and H9N2 avian influenza viruses. In this study, we conducted enhanced surveillance for H7N9 virus in Guangdong, China, from April to August 2013. We isolated two H7N9 viral strains from environmental samples associated with poultry markets and one from a clinical patient. Sequence analyses showed that the Guangdong H7N9 virus isolated from April to May shared high sequence similarity with other strains from eastern China. The A/Guangdong/1/2013 (H7N9) virus isolated from the Guangdong patient on 10 August 2013 was divergent from previously sequenced H7N9 viruses and more closely related to local circulating H9N2 viruses in the NS and NP genes. Phylogenetic analyses revealed that four internal genes of the A/Guangdong/1/2013 (H7N9) virus-the NS, NP, PB1, and PB2 genes-were in clusters different from those for H7N9 viruses identified previously in other provinces of China. The discovery presented here suggests that continuing reassortment led to the emergence of the A/Guangdong/1/2013 (H7N9) virus as a novel H7N9 virus in Guangdong, China, and that viral adaptation to avian and human hosts must be assessed. IMPORTANCEIn this study, we isolated and characterized the avian influenza A H7N9 virus in Guangdong, China, from April to August 2013. We show that the viruses isolated from Guangdong environmental samples and chickens from April to May 2013 were highly similar to other H7N9 strains found in eastern China. The H7N9 virus isolated from the clinical patient in Guangdong in August 2013 was divergent from previously identified H7N9 viruses, with the NS and NP genes originating from recent H9N2 viruses circulating in the province. This study provides direct evidence that continuing reassortment occurred and led to the emergence of a novel H7N9 influenza virus in Guangdong, China. These results also shed light on how the H7N9 virus evolved, which is critically important for future monitoring and tracing of viral transmission.

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“…Previous studies verified the contribution of H9 virus in the process of H7N9 virus evolution [10,11]. However, to our knowledge, no study has assessed the role of H9 virus in relation to the risk of H7N9 virus contamination in the environment.…”

Section: Introductionmentioning

confidence: 85%

Quantitative risk analysis of the novel H7N9 virus in environments associated with H9 avian influenza virus, Zhejiang province, China

Lin

Wang

et al. 2016

Epidemiol. Infect.

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SUMMARYH9 avian influenza virus played a key role during generation of the novel H7N9 virus. A surveillance programme was conducted to assess the H9 virus in relation to the risk of H7N9 virus contamination in the environment. Risk of H7N9 virus contamination in the presence of H9 virus was higher than without (adjusted odds ratio 4·49, 95% confidence interval 3·79-5·31). Adjusted odds ratios of the H7N9 virus associated with co-presence of H9 virus and interacting factors were 4·93 (rural vs. urban area), 46·80 (live poultry markets vs. other premises), 6·86 (Huzhou vs. Hangzhou prefecture), 40·67 (year 2015 vs. 2013), and 9·63 (sewage from cleaning poultry vs. poultry faeces). Regular surveillance on gene variability of H7N9 and H9 viruses should be conducted and extra measures are needed to reduce co-circulation of H7N9 and H9 viruses in the environment.

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Influenza H7N9 and H9N2 Viruses: Coexistence in Poultry Linked to Human H7N9 Infection and Genome Characteristics

Cited by 95 publications

References 24 publications

Avian Influenza H7N9/13 and H7N7/13: a Comparative Virulence Study in Chickens, Pigeons, and Ferrets

Avian Influenza H7N9/13 and H7N7/13: a Comparative Virulence Study in Chickens, Pigeons, and Ferrets

Continuing Reassortment Leads to the Genetic Diversity of Influenza Virus H7N9 in Guangdong, China

Quantitative risk analysis of the novel H7N9 virus in environments associated with H9 avian influenza virus, Zhejiang province, China

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