2006年NPR美国国家公共电台二月-Killer Flu Reconstructed（在线收听） |
| Michelle Norris: From NPR News, this is All Things Considered. I'm Michelle Norris. Robert Siegel: And I'm Robert Siegel. The 1918 flu virus that killed tens of millions of people around the world is back. Scientists have reconstructed it, using pieces of genetic material retrieved from the lungs of people who died 87 years ago. Think Jurassic Park with a virus instead of dinosaurs. In the journals SCIENCE and NATURE researchers say the tightly guarded replica is even more virulent than they are expected. And the virus copy looks ominously like the bird flu virus that is now circulating in Asia. NPR's Richard Knox has the story. Richard Knox: Jeffrey Taubenberger has been obsessed with the 1918 flu virus for years with the sheer mystery of how it wreaked such havoc all over the planet. Jeffrey Taubenberger: Here was an influenza pandemic that killed something like 15 million people. I think we'll never know exactly how many people died. In the United States something like 675 thousand people died. But no one knew anything directly about this virus. Richard Knox: That's because the virus was long gone. But Taubenberger works at the Armed Forces Institute of Pathology in Maryland, in its archives are tissue samples from soldiers killed in that pandemic. Ten years ago Taubenberger began putting together bits and pieces of the 1918 virus's genes from those tissues. The big breakthrough came 5 years ago. A 75-year-old scientist named Johann Hultin retrieved lung tissue from an Alaskan Inuit woman who perished in 1918. Her body had been preserved by her permafrost grave. That allowed researchers to piece together all the virus's genes, but it didn't solve the mystery of the virus's deadly potency. Jeffrey Taubenberger: There were no obviously mutations that popped out at us when it really looked like particularly ordinary influenza virus on paper. Richard Knox: So researchers used a new technology called reverse genetics to make a replica of the virus from its genes. Doctor Terry Tumpey of the Centers for Disease Control and Prevention led the reconstruction process. It was not done in the most high security laboratory, the kind where scientists are incased in head-to-toe armor. Terry Tumpey: They are not full body suits, or space suits which are called in the highest containment. We have half body suits, her whole head is covered. Richard Knox: Tumpey says he wasn't particularly nervous about working with the killer virus, even though the experiments showed that it's about a million times more potent than modern flu viruses. For one thing, most people in the world today now have some immunity to viruses of the 1918 variety called H1N1. 87 years ago, nobody did. Tumpey wouldn't want the replica to escape from the lab, but he doesn't think people should be unduly alarmed, either. Michael Stebbins of the Federation of American Scientists, a science advocacy group, agrees. Michael Stebbins: People should be concerned about work on nasty viruses. But at the same time, you can learn some fundamental things about influenza by working on the actual reconstituted virus. And these are important things to know. Richard Knox: Scientists are already learning some surprising things. Jeffrey Taubenberger thinks the 1918 virus made a great leap from birds to humans with no intermediate step. If true, this sets it apart from later pandemic flu viruses. Jeffrey Taubenberger: This was not a human-bird mixed virus like the 1957 or '68 pandemics, but an entirely birdlike virus in all of its genes that then adapted to humans. So this makes the 1918 virus unique. Richard Knox: That sounds ominously like what may be happening with the H5N1 virus now infecting birds in Asia and so far about 120 humans, killing half of them. Taubenberger thinks the bird virus may need a couple dozen mutations to become as deadly to humans as the 1918 virus. There are signs that the current Asian virus is on the way to acquiring these mutations. Jeffrey Taubenberger: We think that the eerie paralle is that the H5 viruses might be going down this path, but they might not be just fall down that path yet. Richard Knox: Given another year or two, he says, the Asian bird flu virus may become enough like the 1918 virus to reach a pandemic tipping point. As in 1918 nobody in the world would have immunity to it. Not everyone agrees. One skeptic is Peter Palese of Mt. Sinai School of Medicine, a co-author of the reports. Peter Palese: I'm one of the people who is not convinced that the avian flu is imminent. Because there's evidence that the virus has been around for decades. And it hasn't mutated to the amounts of these we are being told it has to evolve into. Richard Knox: But Palese was quick to quote his favorite New York philosopher Yogi Berra, who once cautioned, 'It's tough to make predictions, especially about the future.' Richard Knox: Richard Knox... |
| 原文地址：http://www.tingroom.com/lesson/NPR2006/40776.html |