- The Washington Times - Saturday, June 1, 2002

SAN FRANCISCO (AP) An experimental anthrax antidote has protected rats injected with the bacterium's deadly toxin, according to researchers.

University of Texas at Austin researchers say they have genetically engineered a mouse protein that offers an anthrax toxin a more attractive docking site than its usual target of healthy blood cells.

"This looks like the most promising antitoxin under development," said Dr. Robert Liddington, who studies the poison's atom-by-atom structure at the Burnham Institute in San Diego. "Certainly, if I had late-stage anthrax, I'd pump some of these antibodies into my body."

The research targets that late stage, which is beyond treatment and often fatal. Anthrax infection can be treated with antibiotics early on, but victims rarely know they are infected until it's too late to save them. By then, the anthrax bacteria have flooded the bloodstream with three deadly toxins, and killing the germs with antibiotics may not help much, because the damage is already done.

So several scientific teams across the country have set their sights on those toxins, and the University of Texas research appears to be among the most advanced.

The researchers cautioned that their work, funded by the Department of Defense since 1997, is years away from human tests. Still, they said, the results were promising.

"Although there is a long way to go, our current data make us very optimistic at this point," said Brent Iverson, a chemistry professor at the university and co-author of the study published in the June issue of Nature Biotechnology journal.

In the study, 10 rats were injected with anthrax toxins, five received the antitoxin and five were untreated. The untreated rats died within two hours, while the treated ones survived the five-hour experiment without displaying any anthrax-related symptoms.

The experiment was limited by ethical protocols to five hours, after which the surviving rats were euthanized.

Anthrax makes three toxins to poison cells. One is called protective antigen, so named because it is used to make anthrax vaccine. The other two are edema factor and lethal factor.

Protective antigen starts the process by opening a hole in blood cells that lets in edema factor and the even deadlier lethal factor.

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