As national fears about bioterrorism grow in the wake of the recent terrorist attacks, two Harvard anthrax researchers have found their work thrust unexpectedly into the spotlight.

Anthrax, a bacterial disease that infects livestock and normally poses some risk to humans, is considered one of a number of potential biological weapons. Inhaled anthrax spores kill 90 percent of humans within days of infection.

Presley Professor of Microbiology and Molecular Genetics R. John Collier, who has done research on the proteins that allow anthrax to infect cells, says that he has received about 25 calls from news organizations in the last few weeks.

“It’s certainly much more attention than I’m used to,” he says.

But why has anthrax specifically entered the spotlight?

Dr. Luciana L Borio, a fellow at the Johns Hopkins Center for Civilian Biodefense Studies, says anthrax spores survive well once released and “the size of the spores are perfect for inhalation,” she says. That makes it a perfect weapon for bioterrorists.

And now, the Sept. 11 terrorist attacks have changed the way many people think about the chances of catastrophic terrorism.

“Until now, there’s been no reason why anyone in their right mind would develop a vaccine for plague,” she says. “But that’s all changed.”

Borio says the anthrax baccilus is on the “A” list of diseases capable of causing the most harm if unleashed on a human population.

“I think we’ve always had a threat but the perception has changed,” she says. “People realized that there are not moral limits to what people will do.”

The work of Collier and another Harvard Medical School researcher, Assistant Professor of Genetics William F. Dietrich, focuses on the ways that anthrax enters and destroys cells. Although their research insights are still years away from having clinical benefits for humans, their work has illuminated the molecular aspects of the disease in a way that may eventually be used to fight it.

Collier published a scientific paper in this month’s issue of Nature Biotechnology in which he describes the ability of a protein he discovered to protect rats from anthrax infection. The protein blocks the anthrax toxin’s path into cells.

Working with Mallinckrodt Professor of Chemistry and Chemical Biology George M. Whitesides, Collier bound multiple copies of the protein to a flexible backbone. The connected proteins block the toxin’s entrance into the cell. Separately, Collier has constructed a mutant protein that actually integrates itself into the pore that the toxin enters, blocking its action.

If everything goes well, he says, the mutant protein might yield human therapies in a couple of years.

Borio says the recent attacks are an impetus for research on uncommon but deadly diseases.