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PostPosted: Mon Dec 29, 2014 10:41 pm 
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China, U.S. study retraces emergence of deadly H7N9 strain in humans
English.news.cn 2014-12-30 06:31:13

WASHINGTON, Dec. 29 (Xinhua) -- Chinese and U.S. researchers said Monday they have found how changes in H9N2, a flu virus that has plagued Chinese poultry farms for decades, helped create the novel avian H7N9 influenza that has killed at least 115 people since 2013 and raised a pandemic concern.

The results, published in the U.S. journal Proceedings of the National Academy of Sciences, underscored the need for continued surveillance of flu viruses circulating on poultry farms and identified changes in the H9N2 virus that could serve as an early warning sign of emerging flu viruses with the potential to trigger a pandemic and global health emergency.

H9N2, which has low pathogenicity for avians, was first identified in chicken farms in the south China's Guangdong Province in 1994. Genetic analysis indicated H7N9's six internal genes all originated from H9N2. However, the H7N9 virus is more highly pathogenic in humans than H9N2.

To investigate the H9N2's role in the genesis of the H7N9 virus, researchers at the China Agricultural University, Jude Children's Research Hospital in Memphis, Tennesee, and other research organizations used whole genome sequencing to track the evolution of the H9N2 chicken viruses mainly in farm chickens in China between 1994 and 2013.

The analysis showed that the genetic diversity of H9N2 viruses fell sharply in 2009 and that from 2010 to 2013, an H9N2 virus emerged as the predominant subtype thanks to its genetic makeup that allowed it to flourish despite widespread vaccination of chickens against H9N2 viruses.

The dominant H9N2 virus "had changed antigenicity and improved adaptability in chickens," co-corresponding author Jinhua Liu, professor of the College of Veterinary Medicine at the China Agricultural University, told Xinhua. "That may be one reason for its widespread outbreak from 2010 to 2013."

The emergence of this dominant H9N2 virus, Liu continued, was the first step in the genesis of the H7N9 viruses because it greatly increased the likelihood of reassortment between H9N2 and other flu subtypes. Reassortment refers to the tendency of flu viruses to swap genes.

Before long, the dominant H9N2 virus contributed its six internal genes to the novel H7N9 viruses by reassortment, which has caused two outbreaks of human infection, including at least 375 known cases and 115 deaths since March 2014.

"In the past, we have paid great attention to highly pathogenic forms of avian influenza virus such as H5N1, while low pathogenic forms are largely neglected," Liu said. "But H9N2 has acted as the gene donor for H7N9, H10N8, H6N1 and other viruses that can infect humans, and our study suggests that the prevalence and variation of H9N2 in farmed poultry could provide an early warning of the emergence of novel reassortants with pandemic potential."

http://news.xinhuanet.com/english/health/2014-12/30/c_127345176.htm


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PostPosted: Mon Dec 29, 2014 10:42 pm 
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Evolution of the H9N2 influenza genotype that facilitated the genesis of the novel H7N9 virus

Juan Pua,b,1,
Shuoguo Wangc,1,
Yanbo Yind,1,
Guozhong Zhanga,
Robert A. Carterc,
Jinliang Wanga,
Guanlong Xua,
Honglei Suna,
Min Wanga,
Chu Wena,
Yandi Weia,
Dongdong Wangd,
Baoli Zhue,
Gordon Lemmonc,
Yuannian Jiaoc,
Susu Duanb,
Qian Wanga,
Qian Dua,
Meng Suna,
Jinnan Baoa,
Yipeng Suna,
Jixun Zhaoa,
Hui Zhangf,
Gang Wuc,
Jinhua Liua,2, and
Robert G. Websterb,2

Author Affiliations


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PostPosted: Mon Dec 29, 2014 10:43 pm 
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Significance

The emergence of human infection with a novel H7N9 avian influenza reassortant in China raises a pandemic concern. However, it is not fully understood how these H9N2 chicken viruses facilitated the genesis of the novel H7N9 viruses. Here we show that a “fittest” genotype (G57) emerged with changed antigenicity and improved adaptability in chickens. It became predominant in vaccinated farm chickens and caused widespread outbreaks before the H7N9 virus emergence, increasing reassortment between H9N2 and other subtype viruses and finally providing 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.


Abstract

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.

http://www.pnas.org/content/early/2014/12/25/1422456112.abstract


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PostPosted: Tue Dec 30, 2014 6:31 am 
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Thread on novel H7N9 with H9N2 and H10N8 internal genes

viewtopic.php?f=5&t=13203

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PostPosted: Tue Dec 30, 2014 6:35 am 
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rymich13 wrote:
Evolution of the H9N2 influenza genotype that facilitated the genesis of the novel H7N9 virus

Juan Pua,b,1,
Shuoguo Wangc,1,
Yanbo Yind,1,
Guozhong Zhanga,
Robert A. Carterc,
Jinliang Wanga,
Guanlong Xua,
Honglei Suna,
Min Wanga,
Chu Wena,
Yandi Weia,
Dongdong Wangd,
Baoli Zhue,
Gordon Lemmonc,
Yuannian Jiaoc,
Susu Duanb,
Qian Wanga,
Qian Dua,
Meng Suna,
Jinnan Baoa,
Yipeng Suna,
Jixun Zhaoa,
Hui Zhangf,
Gang Wuc,
Jinhua Liua,2, and
Robert G. Websterb,2

Author Affiliations

Authors
Juan Pu
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
bDepartment of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105;
Shuoguo Wang
cDepartment of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
Yanbo Yin
dCollege of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China;
Guozhong Zhang
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Robert A. Carter
cDepartment of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
Jinliang Wang
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Guanlong Xu
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Honglei Sun
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Min Wang
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Chu Wen
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Yandi Wei
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Dongdong Wang
dCollege of Animal Science and Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China;
Baoli Zhu
eChinese Academy of Sciences Key Laboratory of Pathogenic Microbiology and Immunology, Institute of Microbiology, Chinese Academy of Sciences, Beijing 100101, China; and
Gordon Lemmon
cDepartment of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
Yuannian Jiao
cDepartment of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
Susu Duan
bDepartment of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105;
Qian Wang
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Qian Du
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Meng Sun
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Jinnan Bao
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Yipeng Sun
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Jixun Zhao
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Hui Zhang
fDepartment of Biostatistics, St. Jude Children's Research Hospital, Memphis, TN 38105
Gang Wu
cDepartment of Computational Biology, St. Jude Children's Research Hospital, Memphis, TN 38105;
Jinhua Liu
aKey Laboratory of Animal Epidemiology and Zoonosis, Ministry of Agriculture, College of Veterinary Medicine, China Agricultural University, Beijing 100193, China;
Robert G. Webster
bDepartment of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105;
Footnotes
↵1J.P., S.W., and Y.Y. contributed equally to this work.

2To whom correspondence may be addressed. Email: ljh@cau.edu.cn or robert.webster@stjude.org.
Author contributions: J.P., G.Z., J.Z., and J.L. designed research; J.P., Y.Y., G.Z., J.W., G.X., H.S., M.W., C.W., Y.W., D.W., B.Z., Y.J., Q.W., Q.D., M.S., and J.B. performed research; J.P., S.W., G.Z., R.A.C., J.W., M.W., G.L., Y.S., J.Z., H.Z., G.W., J.L., and R.G.W. analyzed data; and J.P., S.D., G.W., J.L., and R.G.W. wrote the paper.

The authors declare no conflict of interest.

Data deposition: The sequences generated in this study have been deposited in the Genbank database (accession nos. are listed in Table S3).

This article contains supporting information online at www.pnas.org/lookup/suppl/doi:10.1073/p ... pplemental.

Article Information
DOI10.1073/pnas.1422456112

Publication HistoryPublished online before print on December 29, 2014

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