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Scientists find mutations that may let bird flu spread among humans

National Institute of Allergy and Infectious Diseases, National Institutes of Health

Scientists have identified mutations that could allow a lethal strain of bird flu to become more contagious among humans, according to a study in PLOS Pathogens.

Why it matters: The H7N9 strain of bird flu has killed at least a third of the estimated 1500 people it has infected in China since 2013 - and there has been a surge in cases this year. The strain currently doesn't pass easily between people and most cases have occurred after people come in contact with infected poultry. But public health officials are concerned about the potential for H7N9 to mutate into a contagious virus, like other flu viruses have in the past.

What they did: Scientists at the Scripps Institute made mutations to a protein called hemagglutinin that allows the virus to attach to host cells and found that different combinations of three changes in the protein allowed H7N9 to attach to cells found in humans' upper respiratory tract. If the virus evolved to have those mutations, it could theoretically then spread between people by coughing and sneezing, like human flu viruses.

Yes, but... The researchers only altered a fragment of the virus and studied the effect in isolated cells. To assess whether the changes actually yield a virus that can be transmitted, they would like to test them in ferrets (which are often used as a model for studying flu transmission in humans). But, there is currently a moratorium in the U.S. on "gain of function" research that gives a pathogen more capability to cause disease. NPR reports that could soon be lifted.