- Researchers are moving closer to finding
drugs to disarm anthrax and make the deadly bacteria useless as a weapon.
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- Anthrax is a rapid and highly effective
killer. When it infects, the bacteria produces a toxin, or poison, that
attacks cells.
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- Experts consider anthrax-based biological
weapons to be major military threat. Bioterrorism weapons using anthrax
or other bacteria are easier to make and distribute than nuclear weapons.
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- "The only treatment now for anthrax
is to give massive, massive amounts of antibiotics," said Nicholas
S. Duesbery of the cancer institute. "You have to give it almost immediately
after exposure. If you give it 24 hours later, it is too late. Your patient
is dead."
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- "An inhibitor drug would make anthrax
as a weapon as useful as a water pistol," said Dr. George F. Vande
Woude of the National Cancer Institute and a co-author of the study.
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- Anthrax toxin consists of three proteins,
and early research showed that one of the proteins, called lethal factor,
or LF, was the major cause of cell death. But what science didn't know
until now is how LF killed the cells.
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- Vande Woude, Duesbery and their colleagues
found that LF disrupts a signaling system in cells called the MAP-Kinase-Kinase
(MAP-K-K) pathway. When this system is blocked, said Duesbery, a cell "is
cut off from the world." Its metabolism shuts down and it can no longer
divide. The toxin also causes the massive release of an inflammation protein
and destruction of immune system cells called macrophages.
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- The result, said Duesbery, is rapid shock
and death. In laboratory experiments, he said, "rats are quite dead
within just 40 minutes" when injected with anthrax toxin.
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- Now that researchers know the MAP-K-K
target of lethal factor, said Duesbery, "This gives us the first clues
of what we need to develop an antitoxin. We can look at the protein structure
of the target and come up with (a protein molecule) that will block lethal
factor from chopping up its target."
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- Col. Arthur M. Friedlander, an Army anthrax
researcher, said the discovery is significant in understanding how anthrax
kills, but he cautioned that it may take more than a single antitoxin to
disarm the disease.
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- "It is not just that toxin that
kills in this disease," he said. "But this offers a new approach
that may lead to other inhibitors that would work."
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- Ironically, the anthrax cell target was
found while NCI researchers were searching for a way to block the spread
of cancer. Vande Woude said the cell-signaling system that the anthrax
toxin turns off is permanently turned on in some cancers. The goal now
is to use lessons learned from the anthrax research to find a way to selectively
shut down the cell signals that promote cancer, he said.
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- The research is published in the latest
journal Science.
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- Associated Press, Copyright 1998
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- For more News Briefs, and for Feature
Stories, Mind Games, and real-time Expeditions, visit Discovery Channel
Online at http://www.discovery.com.
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