The Flu Hunters: Racing to Outsmart a Pandemic
On April 25, Rod Daniels, the Deputy Director of the World Influenza Center in London, was at a meeting in Germany when he received a call from a co-worker: an influenza outbreak had been reported in Mexico and the first samples of the virus were on their way to London for examination. A virologist who has studied flu for over 30 years, Daniels knew exactly what he was looking for. Influenza A viruses — the type that can cause pandemics — use a protein called hemagglutinin to bind to the cells of their animal hosts. When a virus jumps from animals to humans, its contagiousness is largely determined by what is called the "binding specificity" of this protein. An Alpha-2,3 binding specificity means the virus is well suited to the cells in an animal respiratory tract, but probably not human cells. An Alpha-2,6 binding specificity, on the other hand, means the virus can easily bind to human cells."I got back to the lab and as soon as we saw a sequence of the hemagglutinin, we looked at the receptor binding site and found indications of an Alpha-2,6 binding specificity," Daniels, 54, remembers. "I knew then — we have a problem."
Four months later, and the human race is entrenched in a battle with the H1N1 2009 pandemic virus, with infections reported in 168 countries. In this mortal contest, it's the job of Daniels and his fellow virologists to decode the opponent's playbook. Working in a grim, 1930s building in London's northern suburbs (its exterior was used to portray an insane asylum in the blockbuster [i]Batman Begins[/i]), scientists at the World Influenza Centre receive virus samples from around the world and use sophisticated machinery to map out their genetic structures. During normal years, the scientists concoct the recipe that the World Health Organization (WHO) uses for seasonal flu vaccines. But in a pandemic year, they become vigilantes looking for any changes in the virus that could alter the course of the pandemic.
"Right now this pandemic would appear to be a mild one," says the center's director Alan Hay, 65. "But influenza viruses can change quite suddenly. And there's no reason another, more dangerous, virus couldn't emerge with pandemic potential. It's crucial that we keep our eye on the ball."
Flu's hardiness as a human scourge is the result, paradoxically, of the instability of its genetic structure. One flu virus can easily swap genetic information with another, or mutate as it reproduces. The World Influenza Centre is one of five WHO centers (there are others in Atlanta, Tokyo and Melbourne, and a lab specializing in animal influenza in Memphis) that form the hub of a global influenza surveillance network. The center receives samples taken from ill patients in over 100 countries. By examining the genetic makeup of the viruses in these samples, scientists can make educated guesses about how lethal and contagious a pandemic will be. But they are only guesses. While exhaustive, 21st-century virology can explain and illustrate what's already happened — and help health officials react — the only valid, real-time laboratory is the human population itself.
"If we get reports of a more severe infection with higher mortality rates, we can map the changes that made the virus more severe and monitor its spread. That could help health officials formulate policies," says Hay. "But we are always playing catch-up with flu. It's impossible to stay ahead of this virus." i am really scare the contagious disease.hope everyone can be in a good health!
Specail swine infuenza!be carefull! 华生和福尔摩斯来到报案现场，现场是一片狼籍。凶案现场是躺着的是一个20岁左右的女子。双眼圆睁，仿佛有巨大的冤屈和恐惧。华生看了看死者的头部问到：你认为这是什么凶器造成的？福尔摩斯看到死者头部有尖锐的刀口，但是旁边好象有点被刀子刮掉的碎肉：应该是一把剪刀，普通的刀子是不会有这种刮痕的，凶手很残忍，用剪刀刺进死者头部以后还用力旋转，让死者更痛苦。
华生走到房门边，发现几跟头发，粗而且硬：福尔摩斯，这会不会是凶手留下的毛发？
福尔摩斯拿过来一看：很有可能，凶手应该是一名40岁左右的成年男性，然后他闻了闻，经常酗酒，而且这种酒只能在莫斯科的匹克酒吧才能买到，是那个店自产的伏特加。看得出死者和凶手是经过激烈搏斗的。你来看看。福尔摩斯叫华生过来看死者的头部有一处凹下去的淤痕：凶手很可能先把死者打晕，然后在死者意识模糊的时候下的手，死者倒地，条件反射的抓住了凶手的头发，凶手按住死者用剪刀刺死。
华生说：可是这个房间什么都没有，只有一张床和一个沙发，甚至连凳子都没有，看淤痕应该是用钝物拍击至晕的，你认为会是什么呢？
福尔摩斯大惊到：难道——难道是沙发?!
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