AsianScientist (Apr. 15, 2013) – A genetic analysis of the avian flu virus responsible for at least 11 human deaths in China portrays a virus evolving to adapt to human cells.
The collaborative study, conducted by a group led by Masato Tashiro of the Influenza Virus Research Center, National Institute of Infectious Diseases, and Yoshihiro Kawaoka of the University of Wisconsin-Madison and the University of Tokyo, was published this week in the journal Eurosurveillance.
The group examined the genetic sequences of H7N9 isolates from four of the pathogen’s human victims as well as samples derived from birds and the surroundings of a Shanghai market.
The majority of the virus isolates displayed mutations in the surface protein hemagglutinin, which the pathogen uses to bind to host cells and infect them.
In addition, the isolates from patients contained another mutation that allows the virus to thrive in the cooler temperatures of the human upper respiratory system and gain a hold in a mammalian or human host.
“The human isolates, but not the avian and environmental ones, have a protein mutation that allows for efficient growth in human cells and that also allows them to grow at a temperature that corresponds to the upper respiratory tract of humans, which is lower than you find in birds,” says Kawaoka, a leading expert on avian influenza.
The team also assessed the response of the new strain to drugs used to treat influenza, discovering that one class of commonly used antiviral drugs, ion channel inhibitors, would not be effective; the new strain could be treated with another clinically relevant antiviral drug, oseltamivir.
The findings provide some of the first molecular clues about a worrisome new strain of bird flu, the first human cases of which were reported on March 31 by the Chinese Center for Disease Control and Prevention.
Although it is too early to predict its potential to cause a pandemic, signs that the virus is adapting to mammalian and, in particular, human hosts are unmistakable, says Kawaoka. Access to the genetic information in the viruses, he adds, is necessary for understanding how the virus is evolving and for developing a candidate vaccine to prevent infection.
The article can be found at: Kageyama T et al. (2013) GENETIC ANALYSIS OF NOVEL AVIAN A(H7N9) INFLUENZA VIRUSES ISOLATED FROM PATIENTS IN CHINA, FEBRUARY TO APRIL 2013.
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Source: U-Wisconsin; Photo: kat m research/Flickr/CC.
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