Biodetectives find a way to sniff out anthrax
A virus that naturally preys on spores may help with the rapid detection of the bacteria.
As federal authorities begin tests this week on three New Jersey postal centers for traces of anthrax, scientists say they have discovered a potentially powerful, fast method to detect the bacteria's presence.
Over the long term, the researchers say, the discovery also holds the potential for giving public-health officials new vaccines for treating people affected by anthrax. The treatment's approach, they add, may be applicable to other bioterror agents as well.
Essentially, a team of scientists at The Rockefeller University in New York City have been able to tap properties of a naturally occurring virus that attacks anthrax. In addition to being able to destroy anthrax bacteria, the virus can also detect their presence. Most anthrax-detection tools take a few days, but "our method can detect even low numbers of spores within 20 to 30 minutes" with hand-held equipment that can be used on-site, says researcher Raymond Schuch.
The group's research was funded by the Defense Advanced Research Projects Agency and comes at a time of heightened federal interest in developing countermeasures against biological weapons.
Prompted by last fall's anthrax attacks on a Florida newspaper office and two Senate offices on Capitol Hill, Congress has earmarked $1.5 billion in next year's budget for new labs and research projects aimed at discovering more-effective detection methods and therapies against a range of biological agents.
The results also come at a time of mounting frustration at the difficulties federal investigators face in tracking down the person responsible for last fall's attacks, which killed five people, hospitalized another 13, and led to the vaccination of thousands more.
Earlier this month, traces of anthrax were found in a street-corner mailbox in Princeton, N.J. As a precaution, the US Postal Service tested two regional mail centers on Sunday. They began similar tests on three more yesterday. The results are expected this week.
While such tests are sophisticated and accurate, they also are expensive and time-consuming, notes Dr. Schuch, a research associate at The Rockefeller University's Laboratory of Bacterial Pathogenesis and Immunology and member of the team reporting its results in today's edition of the journal Nature.
The scientists' approach grew out of studies the lab's codirector, Vincent Fischetti, had made of how viruses attack bacteria.
The researchers knew that when a virus enters a bacterial cell, the virus begins to reproduce. Once the offspring reach a certain density within the cell, they produce an enzyme called lysin. The lysin molecules act as biological cannon balls, breaching the cell wall and destroying the bacterium. The offspring then escape to attack other cells.
The team had learned from its previous studies that that lysin also could destroy a bacterial cell from the outside. The question they posed: Would it work on anthrax? They found that it could.
In the process, however, they also realized that once the cell walls were breached, a type of molecule dubbed ATP would escape. These molecules are a cell's energy source. The research team reckoned it could detect the escaped "batteries" by adding an enzyme responsible for the flash in fireflies to give off light. So it proved in their experiments.
One potential shortcoming for this new detection scheme is that it fails to distinguish between virulent and nonvirulent strains of anthrax, note M.J. Rosovitz and Stephen Leppla, researchers at the National Institutes of Health in Bethesda, M.D. Yet the technique would be useful as a fast "first indicator" to detect spores.
Of greater significance is the potential lysin holds as an agent in antianthrax vaccines. "As a potential therapy, this is a highly novel approach one people hadn't recognized before," says Dr. Leppla.
Typically, public-health officials use antibiotics to attack anthrax in addition to other vaccines to counter the toxins' anthrax releases. Many bacteria display an ability to evolve into strains that grow increasingly resistant to antibiotics, the traditional treatment for Anthrax.
Lysin destroys a part of the anthrax cell vital to the bacteria's survival, so it can't evolve an immunity to the enzyme. This trait also would make it extremely difficult for even genetically engineered bioterror agents to survive. The approach is sufficiently promising that Schuch's lab is looking to see if it can be applied to other diseases such as cholera and the plague.