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Just a Few Alterations

Just three changes could transform the hemagglutinin of the H7N9 avian influenza from one suited to attaching to bird cells to one suited to binding human cells, according to a new study.

To determine whether the virus could become more contagious among people, a team of researchers from the Scripps Research Institute conducted a series of mutational analyses on the H7 receptor-binding pocket. As they reported in PLOS Pathogens this week, researchers led by Scripps' James Paulson found that three small changes — at V186G/K-K193T-G228S or V186N-N224K-G228S — made hemagglutinin bind more tightly to human receptors.

"All we've done is to look at one of the properties that we're pretty certain is important," Paulson tells NPR. "So, just because we've changed the one property doesn't mean that that property alone is sufficient to let the virus transmit."

Paulson and his colleagues note in their paper that testing these changes in a ferret model of disease isn't currently allowed due to restrictions on gain-of-function studies. However, NPR notes that the 2014 moratorium may soon be lifted. It says that the US Department of Health and Human Services is just about done drawing up a policy governing the review of such experiments.

"As soon as that policy is finalized, the moratorium will be lifted and [the US National Institutes of Health] will move forward in concordance with that new policy. Our expectation is it will be very soon," Carrie Wolinetz, the acting chief of staff and associate director for science policy at NIH, tells NPR.