1.   But, Friedlander said, it is quite difficult to alter the protective antigen without making the anthrax bacillus ineffective as a weapon.

2.   Collier identified a small protein that would bind with the protective antigen, keeping it from interacting with the anthrax.

3.   Friedlander said all known strains of anthrax share the same basic form of protective antigen.

4.   Protective antigen is designed to dock onto a receptor protein that studs the surface of many cells, even though macrophages are the principal target.

5.   Protective antigen, so named before its true role was understood, serves as the attack vehicle for the other two toxins.

6.   The active ingredient, known as protective antigens, are particles from a dead anthrax bacteria that are used to stimulate the immune system to produce antibodies.

7.   The break-in protein is called protective antigen, a misleading name conferred before its exact role was understood and because it is the protein attacked by the anthrax vaccine.

8.   The Harvard-Wisconsin team discovered the receptor for protective antigen by growing cells in the laboratory on a diet that included a mildly mutagenic chemical.

9.   The molecule blocks a protein, called a protective antigen, that normally ferries the anthrax inside.

10.   The protective antigen then collects lethal factor or edema factor from the bloodstream and injects them into the target cell.