The study found that B. mallei, a highly evolved pathogen that has been deployed in the past as a biological weapon, has an extremely regulated set of virulence genes and an unstable genome that may explain the bacterium's ability to thwart the immune responses of its host animals mainly horses, mules and donkeys.

"The combination of virulence genes and genomic instability may explain why some scientists consider this to be the ultimate bacterial pathogen," says William Nierman, the first author of the study, which is being published in the Proceedings of the National Academy of Sciences (PNAS).

As part of the study, scientists used DNA microarrays to better understand the functions of B. mallei virulence genes. Nierman, an investigator at The Institute for Genomic Research (TIGR), said the new study, along with a report on the related bacterium B. pseudomallei published in the same issue of PNAS, "has dramatically increased our understanding of the biology and pathogenicity of these very sophisticated pathogens."

Even though the symptoms of glanders have been known since the description by Hippocrates in 425 B.C., scientists have yet to develop a vaccine that is effective against this highly infectious equine disease. When humans are infected, treatment requires a long-term regimen of multiple antibiotics. A test developed by German scientists after B. mallei was isolated in 1882 greatly improved the early detection of the disease in horses. Glanders was eradicated in the United States by the 1930s.

Cultures of B. mallei were used as biological weapons during the U.S. Civil War, World War I and World War II. In addition, there have been reports that the Soviet Union weaponized the pathogen and possi
'"/>

Contact: Robert Koenig
rkoenig@tigr.org
301-795-7880
The Institute for Genomic Research
20-Sep-2004