Chemical Neutralizes Anthrax Toxin.

Scientists have created a synthetic compound that disables the toxin that makes the bacterial disease anthrax so lethal. Meanwhile, another research team has discovered a gene that protects some mice against anthrax. These findings could lead to an antidote to the anthrax toxin and help clarify the mechanism by which it kills.

Whether the new compound can serve as an antitoxin in people remains unclear since the scientists have tested it only in rats, says R. John Collier of Harvard Medical School in Boston. Nevertheless, the concept of neutralizing anthrax toxin has appeal because the current treatments, which target the bacterium, and the vaccine now in use have drawbacks.

When a person inhales spores of Bacillus anthracis--the microbe that causes anthrax--they unleash three proteins that combine to form a toxin. This triad makes blood pressure plummet, causes hemorrhaging, and can lead to coma and death.

The proteins attack human cells as a team. One protein--protective antigen (PA)--binds to a receptor on the cell surface and is cleaved by enzymes there. The part of PA that remains stuck, called PA63, provides a docking site for the

other anthrax proteins--lethal factor and edema factor. Once assembled, the toxin enables lethal factor to enter the cell. There, it chops up proteins, setting into motion the chain of events that leads to anthrax's symptoms, says Nicholas C. Duesbery of the Van Andel Research Institute in Grand Rapids, Mich.

Since no drug in use at present disables the toxin, Collier and his colleagues set out to create such a compound. First, they identified a peptide, or partial protein, that bonds to PA63 in lab tests. Next, they linked together multiple copies of the peptide. In test tubes, this synthetic molecule, which they call polyvalent