F1000 Guest Post: Why we are safe, for now, from avian flu

We are delighted to present a guest post from Faculty of 1000 (F1000) on a paper that describes the actual molecular requirements for avian flu to adapt to a human host.

F1000 is a media partner of the Influenza Congress USAWhat would make avian influenza transmissible in humans? This is the question Yoshihiro Kawaoka and his team investigated in their much-anticipated study published in Nature earlier this year. The article, titled "Experimental adaptation of an influenza H5 HA confers respiratory droplet transmission to a reassortant H5 HA/H1N1 virus in ferrets", was recommended by Faculty of 1000 Members Ralf Bartenschlager and Marco Binder of the Infectious Diseases Faculty, and the answer isn’t as frightening as you might think – while the thought of an avian flu pandemic has us all quaking in our boots, Kawaoka’s study serves a much greater purpose than just demonstrating a way to aid this deadly virus’ spread through the human population.

The key to answering the question is the haemagglutinin (HA) molecule, a protein expressed on the surface of viruses that enable them to bind to cells in their host and allow subsequent infection. A subtle difference between sialic acid molecules on the cell surface of the host is the reason behind the H1N1 virus’ virulence – the virus exhibits a "preference" for the avian form, causing it to be so infectious in birds but less so in humans. After identifying a reassortant H5 HA/H1N1 virus, the authors investigated its effect and transmission in ferrets, which are considered appropriate mammalian models for studying influenza transmissibility. Although infection was successful and significant weight loss and lung lesions were observed as a result, the virus was not fatal. Additionally, current vaccines proved effective against the reassortant virus.

Commenting on the study, Bartenschlager and Binder said, "Overall, the study provides a plethora of interesting information on the molecular requirements for an avian H5 HA to adapt to a human host … there is some good news on the pandemic front: the study suggests [that there is] a natural counter selection against spontaneous crossing of the species barrier."

While these findings may evoke a sigh of relief, Kawaoka and colleagues emphasise the importance of their work – the more we know about avian influenza and how it functions on the molecular level, the better prepared we can be for a possible threat. With the rate at which viruses are able to mutate and adapt to better infect their hosts, our continued efforts to prevent future attack will be invaluable.

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Faculty of 1000 is a post-publication review service in Biology and Medicine that identifies and evaluates the most interesting and important papers published worldwide. 10,000 Faculty Members and Associates – experts in their field – cover some 350 defined specialty sections and collectively contribute 1300-1500 article evaluations a month. These evaluations are published immediately on F1000 and constitute an up-to-date and comprehensive guide to the best of the scientific literature.

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