Scientists learn how anthrax kills

Anthrax under the microscope

Discovery might render some biological weapons obsolete

April 30, 1998
Web posted at: 6:16 p.m. EDT (2216 GMT)

WASHINGTON (CNN) -- Researchers at the National Cancer Institute say they have discovered how anthrax destroys cells and causes rapid death -- knowledge that could be used to develop drugs to protect against biological weapons containing the deadly bacteria.

"An inhibitor drug would make anthrax as a weapon as useful as a water pistol," said Dr. George F. Vande Woude, one of the NCI researchers who made the discovery, which is reported in the latest issue of the journal "Science."

Ironically, NCI researchers weren't searching for an antidote for anthrax. Rather, they were searching for new ways to block the spread of cancer, and they are now trying to determine if their new knowledge about how anthrax attacks cells could provide new insight for the fight against cancer.

CNN Medical Correspondent Dan Rutz reports that a group of scientists believe they have discovered how anthrax destroys cells and causes death. 2 min. VXtreme video

Researchers found that a protein in anthrax toxin, called Lethal Factor or LF, disrupts a pathway over which signals are sent into a cell. When that happens, a cell "is cut off from the world" and can no longer divide, said Nicholas S. Duesbery, another of the NCI researchers.

LF also causes the massive release of a protein which causes inflammation and the destruction of immune system cells called macrophages, causing rapid shock and death.

More than one antitoxin may be needed

Now that researchers know LF is the culprit, "this gives us the first clues of what we need to develop an antitoxin," said Duesbery. He said scientists might now come up with a protein molecule that would block LF from wreaking its havoc.

Augmenting that hope is the fact that LF belongs to a class of enzymes called protease, and scientists learned during the fight against AIDS that the effects of protease enzymes can be stopped. Indeed, the new drugs that have been so effective in fighting HIV are called protease inhibitors.

Col. Arthur M. Friedland, an Army anthrax researcher, said the NCI's discovery about anthrax is significant in understanding how it kills. But he cautioned that more than a single antitoxin may be needed to disarm anthrax.

"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."

Weapons experts consider anthrax weapons, which are much easier to make and distribute than nuclear weapons, to be a major threat to civilian populations and troops in the field. Iraq's capacity to make anthrax has been a major concern of United Nations weapons inspectors working there.

Immediate treatment crucial to survival

The U.S. military is now giving all of its troops in the Persian Gulf an anthrax vaccine, and will eventually administer it to all of its personnel. But the vaccine is not 100 percent effective, and most civilians do not receive the shots.

Currently, the only treatment for people exposed to anthrax is massive quantities of antibiotics. But Duesbery said that treatment must be given almost immediately after exposure to have any chance of success.

"If you give it 24 hours later, it is too late. Your patient is dead," he said.

The discovery about anthrax could be used to fight cancer because the same pathway that is turned off by LF is permanently turned on in some cancer cells, causing uncontrolled cell growth. If scientists could find a way to selectively turn off the process, it could be a way to stop cancer growth, Vande Woude said.

Correspondent Dan Rutz and Reuters contributed to this report.

Related stories:

• Iraq denies plot to smuggle anthrax into Britain - March 24, 1998
• Pentagon recalls 200,000 anthrax vaccines destined for Gulf - March 6, 1998
• U.S. troops in Gulf 1st to get anthrax vaccine - March 3, 1998
• Inhaled anthrax can be 'devastating' - February 19, 1998
• Anthrax: An agent of doom - December 15, 1997

Related sites:

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• Centers for Disease Control and Prevention (CDC)
  • Anthrax (Bacillus anthracis) Frequently Asked Questions
  • Case Definitions - Anthrax

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