The Origin of Novel Avian Influenza A (H7N9) and Mutation Dynamics for Its Human-To-Human Transmissible Capacity

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PLoS One. 2014 Mar 26;9(3):e93094. doi: 10.1371/journal.pone.0093094. eCollection 2014.
The Origin of Novel Avian Influenza A (H7N9) and Mutation Dynamics for Its Human-To-Human Transmissible Capacity.
Peng J1, Yang H1, Jiang H2, Lin YX1, Lu CD1, Xu YW1, Zeng J2.
Author information
Abstract

In February 2013, H7N9 (A/H7N9/2013_China), a novel avian influenza virus, broke out in eastern China and caused human death. It is a global priority to discover its origin and the point in time at which it will become transmittable between humans. We present here an interdisciplinary method to track the origin of H7N9 virus in China and to establish an evolutionary dynamics model for its human-to-human transmission via mutations. After comparing influenza viruses from China since 1983, we established an A/H7N9/2013_China virus evolutionary phylogenetic tree and found that the human instances of virus infection were of avian origin and clustered into an independent line. Comparing hemagglutinin (HA) and neuraminidase (NA) gene sequences of A/H7N9/2013_China viruses with all human-to-human, avian, and swine influenza viruses in China in the past 30 years, we found that A/H7N9/2013_China viruses originated from Baer's Pochard H7N1 virus of Hu Nan Province 2010 (HA gene, EPI: 370846, similarity with H7N9 is 95.5%) and duck influenza viruses of Nanchang city 2000 (NA gene, EPI: 387555, similarity with H7N9 is 97%) through genetic re-assortment. HA and NA gene sequence comparison indicated that A/H7N9/2013_China virus was not similar to human-to-human transmittable influenza viruses. To simulate the evolution dynamics required for human-to-human transmission mutations of H7N9 virus, we employed the Markov model. The result of this calculation indicated that the virus would acquire properties for human-to-human transmission in 11.3 years (95% confidence interval (CI): 11.2-11.3, HA gene).

PMID:
24671138
[PubMed - in process]

http://www.ncbi.nlm.nih.gov/pubmed/24671138

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Re: The Origin of Novel Avian Influenza A (H7N9) and Mutation Dynamics for Its Human-To-Human Transmissible Capacity

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Publish research results Sichuan Provincial People's Hospital H7N9 virus may not be new

(2014-04-02 06:46:00) Source: Sichuan Online

Yesterday, the Sichuan Provincial People's Hospital released "H7N9 outbreak will not lead to human transmission in the short term," the research results.

The group leader Dr. Jiang Hua said the results proved that the existing H7N9 virus, if only to get through gene mutation human transmission capability, and that it takes an average of about 11 years. Thus, H7N9 bird flu outbreak will not lead to human transmission in the short term.

Research

Maybe not a new virus H7N9

March 31, Health Department of Hunan Province, the province's new confirmed cases of H7N9 avian influenza case of human infection. Sporadic cases of H7N9 infection appear, this was another public nerve tension. This tension began in the spring of 2012 the winter solstice in 2013, southeast China H7N9 bird flu outbreak.

Spring of 2012, the Sichuan Provincial People's Hospital Trauma Metabolomics Laboratory established a multidisciplinary research group. Since then, Jiang Hua and his colleagues at the time of the H7N9 virus strains Systems Biology, found that in 2013 appeared to infect human H7N9 avian influenza virus, it won two key genes that name already mutated in other poultry can infect people of the state.

Jianghua that these two genes encode the viral infectivity of the two proteins of importance: hemagglutinin (H7) and neuraminidase (N9). Among them, the hemagglutinin of Hunan in 2010 had mutations in diving duck, get the ability to infect human cells. Similarly, neuraminidase even in 2000, in Nanchang ducks in vivo, we have successfully mutated. These findings suggest that now may not be the popular novel H7N9 virus.
Discovery

"Person to person" on average about 11 years

Although the authorities announced that the H7N9 bird flu so far, "person to person" case not found. However, people still worry: Will this virus mutation occurs in the environment, access to "person to person" capability? How long this process takes?

According to reports, the gene sequences of H7N9 virus is relatively conservative, in a few months time, only 2-3 bases mutated. Based on this, the research group will Jianghua genes with 2005 H7N9 virus found in Kunming strain of H2N3 virus from person to person, and were compared with screening, on this basis, the establishment of a model of molecular evolution, and use of existing Data for the mutation rate of H7N9 virus were estimated and found that the existing H7N9 virus, if only to get the "person to person" capability through genetic mutation, that it takes an average of about 11 years.

March 26, 2014, related to the research papers in internationally renowned scientific journal "Public Library of Science journal" (PLOS ONE) published.

Proposal

Chicken duck soil may be more secure than the market

Jianghua introduced daily life to avoid direct contact with live poultry, birds or their droppings, especially sick or dead poultry. Children should avoid direct contact with poultry and wild birds. He mentioned, every holiday, people often used to return home with the so-called native chickens, ducks, etc., he suggested that it is best not so. "Do you think that unsafe poultry market, but it may go to the market to buy more than safe."

He suggested that the industrial slaughter on the informal market, whether it is public or staff are slaughtered there is a protection. The best is to regulate agricultural markets, buying chickens and ducks have been slaughtered, etc., can largely avoid direct exposure to the virus.

Migratory birds "play" a disaster

Reporter: You mentioned that H7N9 is not a new virus, which in the end is how come?

Ganghwa: The results showed that the H7N9 epidemic was probably not a new virus. It originated in the Poyang Lake - Dongting Lake water birds, very likely a group from Australia to Siberia migratory birds in Poyang Lake via China - when the Dongting Lake, and from the left due to multiple viruses evolved.

Reporter: Previously, the view, said the existence of the mysterious flu pandemic "ten year interval", this cyclical and sunspot activity are linked.

Ganghwa: Avian periodically touching interpersonal communication, it may just be the next large-scale random mutation, the mutation of the bird flu virus spread from one mode to another mode of transmission in the mean time, while the relationship between sunspots and not conjecture large.

Sichuan Provincial Academy of Medical Sciences & Sichuan Provincial People's Hospital Trauma metabolomics multidisciplinary laboratory was established in 2009, is now Sichuan Key Laboratory of Medical Sciences & Sichuan Provincial People's Hospital.

Ganghwa: Sichuan Academy of Medical Sciences & Sichuan Provincial People's Hospital, deputy director of trauma metabolomics multidisciplinary laboratory, MD. Domestic metabolomics, computational biology, clinical data mining renowned experts. International and domestic scientific journals published 40, an editor of professional books, six senate professional books.

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