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Chinese Researchers Pinpoint Origins Of H7N9 Avian Flu

Chinese researchers have identified the origins of the novel H7N9 influenza virus that has led to 109 human infections and 22 deaths in China.

| April 29, 2013 | In the Lab

AsianScientist (Apr. 29, 2013) - Chinese researchers have identified the origins of the H7N9 influenza virus that has led to 109 human infections and 22 deaths in China.

In March 2013, a novel H7N9 influenza virus was identified in China as the source of a flu-like disease in humans. A group of scientists, led by Professor Chen Hualan of the National Avian Influenza Reference Laboratory at the Harbin Veterinary Research Institute, investigated the origins of this novel H7N9 influenza virus.

The researchers first collected a total of 970 samples 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 which were 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.

After further analysis, they found that the novel H7N9 viruses are reassortants in which the six internal genes were derived from H9N2 avian viruses; however the origins of their hemagglutinin (HA) and neuraminidase (NA) genes were unclear.

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, and 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.

"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," say the authors.

The article can be found at: Shi JZ et al. (2013) Isolation and characterization of H7N9 viruses from live poultry markets—Implication of the source of current H7N9 infection in humans.


Source: Science in China Press; Photo: Sanofi Pasteur/Flickr/CC.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.

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