The bioterrorist threat with regard to Bacillus anthracis requires the development of improved vaccines, diagnostic, and therapeutic agents. Bacterial cell surface carbohydrates have been utilized for all three of these purposes, however, little is known about the B. anthracis cell wall carbohydrates. B. anthracis produces a capsule consisting of poly-g-glutamic acid, rather than a polysaccharide. However, recent work has shown that there are important carbohydrate components in both the vegetative and spore forms of B.anthracis. The vegetative cell wall contains a polysaccharide that is linked to peptidoglycan and serves to anchor the crystalline surface (S-layer) protein to the cell wall by binding with the SLH domain of the protein. This polysaccharide is referred to as the S-layer anchoring polysaccharide. The exosporium coat of the spore contains a major glycoprotein that is an immunodominant antigen of the spore. While the structure of the S-layer anchoring polysaccharide has not been determined, indirect data suggest that it has structural features that are specific to B. anthracis. There are no reports characterizing the carbohydrates of the exosporium glycoprotein. It is hypothesized that the B. anthracis cell wall contains carbohydrates (e.g. the S-layer anchoring polysaccharide and the exosporium glycoprotein) that are species and/or strain specific and are, therefore, candidates for the development of vaccines, diagnostic and therapeutic agents.
The specific aims of this application are to (a.) determine if the S-layer anchoring polysaccharide and the exosporium carbohydrates have species specific structural features, (b.) determine if these same carbohydrates have strain specific structural features, and (c.) determine if the B. anthracis virulence plasmids, pX01 and pX02, encode for enzymes that structurally modify these carbohydrates. This work will be done by isolating and structurally characterizing these carbohydrates from several species of the B. cereus group, including B. anthracis var Ames, from several strains/isolates of B. anthracis, and from B.anthracis var Ames derivatives that have been differentially cured of pX01 or pX02, or of both plasmids. This work will be a collaborative effort between Dr. Russell Carlson at the Complex Carbohydrate Research Center at the University of Georgia, Dr. David Stephens at Emory University, and Dr. Conrad Quinn at the Centers for Disease Control.
