July 2, 2003 In a new study, NYU School of Medicine researchers have found what may be an Achilles' heel of deadly anthrax -- a system that the bacteria use to communicate their presence to others of their kind. The researchers, Martin Blaser, M.D., the Frederick King Professor and Chairman of the Department of Medicine, and Professor of Microbiology and graduate student Marcus Jones, describe a "quorum-sensing system" in anthrax that is a type of bacterial "calling card." Disrupting this system may open new avenues to prevention and treatment of anthrax, says Dr. Blaser.
"It is essential that we pursue new vaccines and therapies to control anthrax, a highly lethal bacterial infection and a potential bioweapon," says Dr. Blaser. "Now that we know that anthrax has a quorum-sensing system it may be possible to develop specific antagonists or inhibitors," he says.
Previously, a quorum-sensing system had not been identified in Bacillus anthracis, the scientific name for anthrax. The School of Medicine researchers now describe such a system in a study appearing in the July issue of the journal Infection and Immunity, published by the American Society for Microbiology.
In the study, the NYU researchers identify a gene, called luxS, in the anthrax bacterium, which is part of a quorum-sensing system. They show that this molecule is necessary for the robust growth of the bacterium in test tubes. The lux pathway was first identified in bioluminescent bacteria, which allows the bacteria to glow under certain conditions. The researchers demonstrate that anthrax has such a pathway through a series of experiments using Vibrio harveyi, a bioluminescent bacterium, to detect the signal produced by the anthrax bacteria.
Microbiologists had once considered bacteria to be fairly simple single-cell organisms that lacked sophisticated signaling systems found in multi-celled animals. Over the last 30 years, this notion has been overturned completely as scientists have discovered a "quorum-sensing" signaling system in a wide range of bacteria, from innocuous bioluminescent microbes that light up the ocean to notorious bacteria that kill thousands of people each year.
This system allows a bacterium to monitor its environment. It tells the microbe how many other bacteria are in the neighborhood, and possibly whether they are of the same type. When a certain number of the bacterium gather in one place, the system sends out a signal that it is time to turn on other functions, such as lighting up or releasing deadly toxins. Such a system allows bacteria to reserve their energy until they gather in a big group, when they can perform some functions more effectively.
Many researchers are avidly studying quorum-sensing systems in other pathogenic (disease-causing) bacteria in the hopes of finding new ways to prevent or treat disease. They believe it may be feasible to prevent bacterial damage by dismantling or disrupting the communications system.
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