Government-funded scientists make advance in biodefense

Scientists at Rockefeller University in New York, with full funding from the Defense Advanced Research Projects Agency, have developed a biological agent that can detect anthrax bacteria at very low levels, significantly advancing bioterrorism defense efforts to quickly detect the presence of anthrax outside a laboratory.

The detecting agent is an enzyme produced by a virus that attacks only anthrax, said Dan Nelson, a post-doctoral fellow and research team member at the university's Laboratory of Bacterial Pathogenesis and Immunology. The virus replicates when it infects anthrax bacteria, and the offspring escape from inside the bacteria by releasing the enzyme, called a lysin, which drills through the bacteria's cell wall. Nelson said the research team found that the lysin enzyme could also bore into the anthrax bacteria cell from the outside. The researchers applied the enzyme directly to anthrax bacteria, causing its contents to rupture and spill out. Those contents then mixed with another enzyme the researchers added called luciferase, which is found in fireflies. The result: microscopic contents actually light up when in contact one another. A device called a luminometer detects these light pulses at very low levels. Before scientists can test a substance for anthrax, it must be in bacterial form. Anthrax spores are germinated, or forced to grow into bacteria, for testing purposes. The new enzyme test conducted by the Rockefeller scientists is significant because it can detect bacteria grown from only 2,000-2,500 spores of anthrax. The test produces a result in less than 10 minutes, Nelson said. Currently, hand-held anthrax detectors, like those used after the anthrax attack on the Hart Senate Office Building, can only detect bacteria from spores in concentrations of 7,000-10,000. That's the amount epidemiologists previously thought was lethal in humans. However, after last October's anthrax attacks, in which five people died from inhaling anthrax spores, scientists now question what the actual lethal dose is. Nelson said the research team has even managed to detect bacteria from as few as 100 spores. That took about an hour, but is still a remarkable advancement over other accurate but time-consuming tests that must be performed in a laboratory setting. New Horizons Diagnostics, a testing device manufacturer in Columbia, Md., plans to obtain quantities of the Rockefeller enzyme within the next six months, said Cheryl Trudil, the company's marketing manager. New Horizons manufactures luminometers and could manufacture the enzyme and use it in hand-held anthrax testing devices. The Rockefeller scientists also found their enzyme to be a remarkably effective treatment for anthrax infection, Nelson said. The team infected mice with a noncontagious cousin bacteria of anthrax, known as bacillus cereus. Those bacteria kill mice within four hours. However, after being treated with the enzyme 15 minutes after infection, 70 to 80 percent of the mice lived. Nelson said the research team will test the enzyme on larger animals over the next several months. The Defense Advanced Research Projects Agency is most interested in the enzyme as a treatment for anthrax infection. Nelson said the enzyme could be highly effective when used in conjunction with antibiotics such as Cipro. The team reported its research in the Aug. 22 issue of the journal Nature.