The scientists research, conducted during the past year, will be presented today during a session at the general meeting of the American Society for Microbiology at the Salt Palace Convention Center.

In her presentation, Livermore biomedical scientist Lyndsay Radnedge will discuss how the researchers have found 20 DNA regions or "signatures" unique to Bacillus anthracis, the bacterium that causes anthrax.

Currently, most DNA-based tests for B. anthracis are based on plasmid sequences, which can be genetically unstable, occasionally yielding false positives or false negatives. A plasmid is a small piece of DNA separate from the chromosome that is transferable between microorganisms.

The new DNA signatures represent an increased repertoire of chromosomal markers that can be used for anthrax detection.

The teams DNA signatures, which range from about 100 bases of DNA to 800 bases of DNA, were derived from the Ames strain of the B. anthracis bacterium. A robust set of DNA signatures should produce no false negatives for all strains of B. anthracis, and no false positives for closely related bacteria.

"Significantly, the DNA signatures weve discovered are found in all of the diverse strains of B. anthracis in the culture collection at NAU," Radnedge said.

The signatures are being checked against and are so far different from other strains of Bacillus and related microbes. Of equal importance, they are not represented in the collection of pathogenic non-anthrax Bacillus strains so far examined, decreasing the possibility of false positive results.

During the next two months or so, the DNA signatures will und
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Contact: Steve Wampler
wampler1@llnl.gov
925-423-3107
DOE/Lawrence Livermore National Laboratory
22-May-2002