Chinese scientists have discovered that a type of H7N9 can bind with a human receptor, which explains how the virus can infect human beings.
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Research focused on how H7N9 infected human beings, examining the two earliest reported virus types, known as isolates. These were SH-H7N9 and AH-H7N9, discovered in Shanghai and Anhui province respectively.
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Researchers evaluated the viral hemagglutinin receptor binding properties of the two isolates. A receptor is a protein molecule in a cell, or on a cell, to which a substance can bind. A virus has to combine with a receptor in order to infect the host.
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Researchers found that SH-H7N9 (reported in Shanghai) preferentially binds the avian receptor analog, whereas the AH-H7N9 (reported in Anhui) binds both avian and human receptor analogs.
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The research titled "Structures and receptor binding of hemagglutinins from human-infecting H7N9 influenza viruses", jointly authored by a team from the Chinese Academy of Sciences, was published online on September 5 by Science, a leading journal.
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Shi Yi, researcher with the academy and lead author of the paper, said AH-H7N9 was prevalent during the outbreak, whereas SH-H7N9 was only isolated from one case.
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Researchers warned the H7N9 virus must be closely monitored in case of mutation.
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H7N9 bird flu has killed 45 people on the Chinese mainland since the first human infection was confirmed in late March. A total of 134 cases of H7N9 human infection have been confirmed, according to China's health authorities.