美国国家公共电台 NPR A Few Genetic Tweaks To Chinese Bird Flu Virus Could Fuel A Human Pandemic（在线收听）

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Public health officials are increasingly worried about a strain of bird flu virus that's circulating in China. In the last nine months it's sickened more than 700 people, and about 40 percent of them died. Now a team of researchers from the U.S. and the Netherlands has new information on what might cause this virus to start spreading more widely. NPR's Nell Greenfieldboyce reports.

NELL GREENFIELDBOYCE, BYLINE: Right now people seem to get the H7N9 bird flu virus from, well, birds. It isn't capable of spreading from person to person to person to person. But what if that changed?

JAMES PAULSON: We're trying to just understand the virus so that we can be prepared.

GREENFIELDBOYCE: Jim Paulson is a biologist at the Scripps Research Institute. He and some colleagues recently tinkered with a piece of this bird flu, a protein that lets the virus latch on to cells.

PAULSON: So it's not the whole virus. It's just a fragment that we can then study for its properties.

GREENFIELDBOYCE: They found that it only takes three little changes to make this protein capable of hooking on to human cells. That could help the virus start spreading between people, although Paulson cautions that other changes might be necessary.

PAULSON: There may be several other genes that are important for transmission that we don't know about.

GREENFIELDBOYCE: Now, one way of finding out would be to make those three changes in the actual virus in a highly secure lab and see what happens. Does it become contagious in lab animals? Well, scientists like Paulson can't do that experiment because in 2014 the Obama administration stopped all federally funded work that might make flu viruses more dangerous. That's because critics argued that scientists shouldn't be in the business of deliberately making deadly flu viruses even worse. What if a lab-made virus escaped or got stolen for use as a bioweapon?

PAULSON: I admit that - you know, that some people have real reservations about it. I mean, these are all legitimate concerns, in my view.

GREENFIELDBOYCE: That's why Paulson wants to test these mutations not in the deadly H7N9 bird flu virus itself but rather in a weakened flu virus. And that may soon be possible. Government officials are drafting a new system for how they'll review flu experiments to decide what can go forward. Carrie Wolinetz is associate director for science policy at the National Institutes of Health, which funds flu research. She says once that policy is finished the moratorium will be lifted.

CARRIE WOLINETZ: Our expectation is it will be very soon.

GREENFIELDBOYCE: It's not clear what exactly will be permitted under the new policy. And after years of debate, it seems like scientists still have reached no consensus on how to balance the risks and the benefits. David Relman is a biologist at Stanford University. He'd be OK with putting these mutations in a weakened virus, but putting them in the H7N9 virus...

DAVID RELMAN: I would be very hesitant to see them do that experiment and try it out.

GREENFIELDBOYCE: Other scientists say we have to experiment with H7N9. Ron Fouchier is a virologist at Erasmus Medical Center in the Netherlands who studies flu with U.S. funding. He says at the end of the day you need to alter the real flu virus you're worried about to know what it's really capable of. He thinks U.S. officials will agree. But even if they don't...

RON FOUCHIER: The rest of the world is moving forward with this type of experiment already. And so the U.S. can either join or not join. It's up to them. But the work will continue.

GREENFIELDBOYCE: He hopes that officials will reveal more about their plans when federally funded flu researchers meet next month in Atlanta. Nell Greenfieldboyce, NPR News.

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