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New Scientist

Have Cold Bashers Dealt The Virus A Deadly Blow?

Drugs can leave a virus breathless. Researchers in the US have found that parts of the protein shell of the common cold virus flap open in a motion they call "breathing"--and compounds that stop viruses infecting cells can stifle this flapping. The discovery could lead to rapid screening methods for antiviral drugs.

A virus only shows real signs of life after it has infected a cell. Once inside, the invader sheds its protective protein coat, releases its genetic material and hijacks the cell's resources to replicate itself. But according to the textbooks, viruses shut down between infections, becoming as inanimate as a stone.

But now Thomas Smith, a biochemist at Purdue University in Lafayette, Indiana, says that this is not the full story. Smith studies the rhinovirus which causes the common cold. "We know that proteins move in solution," he says. "But it's hard for most people to visualise the virus as dynamic, so they don't."

Until now, many scientists were also convinced that the fluctuations in viral shape that happened outside the cell were probably minor and of little importance. So when Smith teamed up with chemist Gary Siuzdak and his colleagues at the Scripps Research Institute in La Jolla, California, to probe the motions of the virus coat, the best he hoped for was to reveal a tiny twitching. "Even that, I thought, might be blue-sky thinking," he says. The researchers treated the virus with an enzyme that chops up proteins. They reasoned that if the breathing effect was only small, exposing just the outermost atoms of the virus's coat, then the first wounds the enzyme inflicted on the virus should be in these layers.

In most cases, this turned out to be true. But to the team's surprise, one protein, called VP4, was also an early victim-even though previous studies showed that it was usually buried inside the virus, 25 atom lengths from the surface. "That's a lot of breathing," says Smith. "You think: how the devil could that get out?"

New Scientist issue 20th June 1998, page 19

Author: Philip Cohen

PLEASE MENTION NEW SCIENTIST AS THE SOURCE OF THIS ARTICLE

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