A group of scientists, led by Professor Chen Hualan (National Avian Influenza Reference Laboratory, State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences) have investigated the origins of this novel H7N9 influenza virus (Shi et al., 2013).
Following analysis of H7N9 influenza viruses collected from live poultry markets, it was found that these viruses circulating among birds were responsible for human infections. These novel H7N9 viruses are reassortants in which the six internal genes were derived from avian H9N2 viruses; however the origins of their hemagglutinin (HA) and neuraminidase (NA) genes were unclear.
A total of 970 samples were collected from live poultry markets and poultry farms located in Shanghai and Anhui Province. Samples analyzed included drinking water, feces, contaminated soil, and cloacal and tracheal swabs. Of these samples, 20 were positive for the presence of H7N9 influenza viruses. All of the positive samples originated from live poultry markets in Shanghai. Of these 20 positive samples, 10 were isolated from chickens, 3 from pigeons, and 7 were from environmental samples.
The complete genome of three H7N9 isolates, from a chicken, pigeon, and environmental sample, was sequenced and deposited into the GISAID database. Genetic analysis of these isolates revealed high homology across all eight gene segments. Phylogenetic analysis of these novel H7N9 influenza virus isolates showed that that the six internal genes were derived from avian H9N2 viruses, but the ancestor of their HA and NA genes is unknown. According to the GenBank database, the HA genes of the novel isolated viruses were most similar to those from duck H7N3 influenza viruses, sharing 95.2.8% homology at the nucleotide level. The NA gene of the novel H7N9 virus isolates shared highest homology (97.3.9%) with NA genes from H4N9 or H11N9 influenza viruses isolated from ducks, and environmental samples from duck farms, located in the Dongting Lake region. It is clear that the novel H7N9 viruses are the product of gene reassortment, with the internal genes from one donor, and HA and NA genes from one or several other donors.
HA receptor-binding specificity is a major molecular determinant for the host range of influenza viruses. Amino acids at positions 226 and 228 of HA are critical for specificity of receptor-binding in influenza viruses. Within the HA protein of novel H7N9 viruses, there was a leucine residue at position 226, which is characteristic of the HA gene in human influenza viruses. This finding implies that H7N9 viruses have partially acquired human receptor-binding specificity. All of the H7N9 human isolates examined contained a lysine residue at position 627 in the PB2 protein. It is well known that this lysine residue contributes to the replication and transmission of avian influenza viruses in mammalian hosts. It is likely that the acquisition of this lysine in H7N9 viruses during their replication in human hosts has significantly contributed to their virulence and lethality in humans.
Tracing the source of these novel H7N9 influenza viruses, and their subsequent characterization, was a collaborative effort involving researchers from the National Avian Influenza Reference Laboratory at the Harbin Veterinary Research Institute, and Shanghai Animal Disease Control Center. This research project was partially supported by the National Basic Research Program of China (2011CB505000), the China Agriculture Research System (CARS-42-G08), and the National Science and Technology Major Project (2012ZX10004214). We suggest that strong measures, such as continued surveillance of avian and human hosts, control of animal movement, shutdown of live poultry markets, and culling of poultry in affected areas, should be taken during this initial stage of virus prevalence to prevent a possible pandemic. Additionally, it is also imperative to evaluate the pathogenicity and transmissibility of these H7N9 viruses, and to develop effective vaccines and antiviral drugs against so as to reduce their adverse effects upon human health.
corresponding author:CHEN HuaLan
YAN Bei | EurekAlert!
TSRI researchers develop new method to 'fingerprint' HIV
29.03.2017 | Scripps Research Institute
Periodic ventilation keeps more pollen out than tilted-open windows
29.03.2017 | Technische Universität München
The Institute of Semiconductor Technology and the Institute of Physical and Theoretical Chemistry, both members of the Laboratory for Emerging Nanometrology (LENA), at Technische Universität Braunschweig are partners in a new European research project entitled ChipScope, which aims to develop a completely new and extremely small optical microscope capable of observing the interior of living cells in real time. A consortium of 7 partners from 5 countries will tackle this issue with very ambitious objectives during a four-year research program.
To demonstrate the usefulness of this new scientific tool, at the end of the project the developed chip-sized microscope will be used to observe in real-time...
Astronomers from Bonn and Tautenburg in Thuringia (Germany) used the 100-m radio telescope at Effelsberg to observe several galaxy clusters. At the edges of these large accumulations of dark matter, stellar systems (galaxies), hot gas, and charged particles, they found magnetic fields that are exceptionally ordered over distances of many million light years. This makes them the most extended magnetic fields in the universe known so far.
The results will be published on March 22 in the journal „Astronomy & Astrophysics“.
Galaxy clusters are the largest gravitationally bound structures in the universe. With a typical extent of about 10 million light years, i.e. 100 times the...
Researchers at the Goethe University Frankfurt, together with partners from the University of Tübingen in Germany and Queen Mary University as well as Francis Crick Institute from London (UK) have developed a novel technology to decipher the secret ubiquitin code.
Ubiquitin is a small protein that can be linked to other cellular proteins, thereby controlling and modulating their functions. The attachment occurs in many...
In the eternal search for next generation high-efficiency solar cells and LEDs, scientists at Los Alamos National Laboratory and their partners are creating...
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are less stable. Now researchers at the Technical University of Munich (TUM) have, for the first time ever, produced a composite material combining silicon nanosheets and a polymer that is both UV-resistant and easy to process. This brings the scientists a significant step closer to industrial applications like flexible displays and photosensors.
Silicon nanosheets are thin, two-dimensional layers with exceptional optoelectronic properties very similar to those of graphene. Albeit, the nanosheets are...
20.03.2017 | Event News
14.03.2017 | Event News
07.03.2017 | Event News
29.03.2017 | Materials Sciences
29.03.2017 | Physics and Astronomy
29.03.2017 | Earth Sciences