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University of Georgia researchers discover cell-wall carbohydrate that is crucial to anthrax bacterium

October 02, 2006

Athens, Ga. - A week after the 9/11 attacks in 2001, the letters began to arrive. Someone filled envelopes with a deadly strain of anthrax bacteria and mailed them to two U.S. senators and several offices of the news media. Five people died, and 17 others became infected.

Since that time, governmental authorities have been engaged in a race to find ways to keep citizens safe if terrorists attack again with Bacillus anthracis, the bacterium that causes anthrax. Now, researchers at the University of Georgia, collaborating with scientists at the federal Centers for Disease Control and Prevention (CDC) in Atlanta, have discovered the structure of a unique cell-wall carbohydrate in B. anthracis.

The unique nature of the carbohydrate makes the molecule an important target for evaluating its role in virulence and survival of the anthrax bacterium, the development of new diagnostic tests and perhaps even as a new vaccine additive.

Russell Carlson of the department of biochemistry and molecular biology at the University of Georgia and faculty member at UGA's Complex Carbohydrate Research Center (CCRC), was corresponding author on a paper reporting the research, which was just published in the online version of the Journal of Biological Chemistry. Other authors from the CCRC include Biswa Choudhury, Christine Leoff, Elke Saile and Elmar Kannenberg. Collaborators at CDC were Patricia Wilkins and Conrad P. Quinn.

Anthrax is a naturally occurring animal disease. This year alone there have been several large outbreaks in animals in the U.S. and Canada, so understanding the structure of important parts of B. anthracis has a wide variety of potential applications. The new UGA research is not directly about vaccine development, and much more research needs to be done before the full potential of this unique anthrax molecule is understood.

The problems facing researchers as they unravel all the molecular riddles of anthrax are enormous. There are more than 100 known strains of B. anthracis, and one of the most virulent is called the Ames Strain. It is this strain that was mailed to victims in the fall of 2001.

Effective vaccines and antibiotics against anthrax do exist. Indeed, the federal government began Project BioShield, a $5.6 billion initiative, even before the last anthrax letter was delivered in 2001. Still, a New York Times story on September 18 reported that despite a $900 million "push to add a new anthrax vaccine to the stockpile," there have been setbacks. The Times reported that "only a small fraction of the anticipated remedies are available."

As a first step in understanding the structure and function of cell wall carbohydrates, the research team examined four Bacillus anthracis strains - Ames, Pasteur, Sterne and UT60 - and compared them to two related strains of Bacillus cereus, a soil-dwelling bacterium that causes food-borne illnesses. Cultures of these strains and the initial cell wall preparations were prepared by CDC researchers in their biosafety labs.

One important discovery in the just-reported research is that the newly discovered carbohydrate in the cell wall of B. anthracis is "species specific"; that is, of the strains tested, it was only found in the anthrax bacterium. This is one of several necessary conditions for a molecule that may be used to prepare rapid diagnostic tests for anthrax.

The research was supported by grants from the National Institutes of Health (to Carlson) and the U.S. Department of Energy (to the CCRC).

University of Georgia