When the mutant form was injected together with the normally lethal mix of anthrax toxin, laboratory rats did not develop any symptoms of poisoning, according to the study appearing in the journal Science. Rats infected with the toxin without the mutant variation became moribund within 90 minutes. Anthrax is a bacterial disease that generally infects animals such as cattle, sheep and hippopotamuses. It rarely infects humans, but could pose a devastating threat if anthrax spores are used in a biological weapon by terrorists or in warfare. Not surprisingly, the findings have drawn the interest of the U.S. military.
Death is caused by the toxin produced by the bacteria.
In its airborne form, a mere teaspoonful of anthrax could wipe out hundreds of people. A big worry is the possible release of anthrax by terrorists in an urban setting. The Harvard team sought to prevent infection using forms of the anthrax bacterium with a mutation in a toxin component called protective antigen. These assemble into the toxin on the outside surface of human cell membranes. For symptoms to develop, lethal factor and edema factor must move to the cell interior.