Findings by a research team could eventually lead to the development of a protease inhibitor drug, which in combination with antibiotics could be used to treat anthrax cases later in the disease, at a point when antibiotics alone are no longer effective. “Unlike most types of bacteria, bacillus anthracis has the ability to produce large amounts of a toxin that can kill the patient even after antibiotics have destroyed the bacteria,” explains the study’s senior author, Lewis Cantley, chief of the Division of Signal Transduction at Beth Israel Deaconess Medical Center (BIDMC) and professor of systems biology at Harvard Medical School. “This toxin is released within days of the initial infection, and is impervious to antibiotics.” Using a “mixture-based peptide library” technique developed by BIDMC scientist Benjamin Turk, the researchers analyzed trillions of peptides to determine an optimal peptide substrate for lethal factor, the active agent in the anthrax toxin. Funding for this study came from the National Institutes of Health, the U.S. National Science Foundation and the U.S. Army. The discovery was described in the January 2004 issue of Nature Structural & Molecular Biology.