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TIGR Says Lesser-Known Anthrax Cousin May Be More Pathogenic

NEW YORK, May 17 (GenomeWeb News) - Pointing to a novel threat in the pantheon of potential biowarfare agents, a research team from the Institute for Genomic Research and the US Centers for Disease Control and Prevention published new findings that a strain of Bacillus cereus can be as pathogenic as its cousin, Bacillus anthracis.

 

The group sequenced the genome of a B. cereus strain that was obtained by the CDC from a patient who during the 2001 anthrax attacks in the United Statessuffered an anthrax-like illness. They found that this isolate, strain G9241, contained a toxin-coding plasmid that was 99.6 percent identical to that of a similar plasmid in B. anthracis, the PX01 plasmid, which contains the gene for anthrax lethal factor.

 

This strain "will kill a mouse faster than B. anthracis," said Jacques Ravel of TIGR, a lead researcher in this study, in a recent talk on this research. Additionally, Ravel said, the finding raises potential issues for the identification of B. anthracis in clinical samples, and "highlights the challenges labs are going to have in the future." 

 

TIGR's findings are slated to be published in the June 1 issue of the Proceedings of the National Academy of Sciences, and will be made available online late today.

 

Because the toxin-encoding plasmid varied from the ordinary PX01 plasmid, it also raises the possibility that terrorists or others "might be able to obtain a novel anthrax toxin which might be able to evade [an anthrax] vaccine," Ravel said.

 

Ravel spoke on this finding and other aspects of TIGR's anthrax research at the Genomes 2004 conference in the United Kingdomlast month, filling in for TIGR president Claire Frasier, who was unable to attend due to illness.

 

Ravel detailed how this B. cereus isolate was biochemically and phenotypically different from B. anthracis: It was hemolytic and motile, and produced a thick capsule, unlike B. anthracis.

 

Additionally, the researchers found that the B. cereus strain included a second plasmid y that differed significantly from the second anthrax pathogenicity plasmid, PX02, and contained a novel sugar capsule cluster not found in other strains of B. cereus. This sugar cluster could play a role in the virulence of this isolate.

 

In his presentation, Ravel also discussed the comparative sequencing work that TIGR has conducted on strains of B. anthracis. After doing 12x sequencing, the group compared genomes of six diverse strains. These comparisons have shown that there are "few differences at the genome level between strains," Ravel said. TIGR has been able to use the data obtained from comparative sequencing to generate a phylogenetic tree of B. anthracis strains, but still is working on sequencing and analyzing additional strains.

 

While some of TIGR's work on anthrax will not be made public because it is part of the US Federal Bureau of Investigation inquiry into the 2001 anthrax attacks in the United States, Fraser has previously advocated for public disclosure of anthrax sequence data.

 

TIGR's work on the B. anthracis study was funded by the National Institute of Allergy and Infectious Diseases through the PathogenFunctionalGenomicsResourceCenterat TIGR. NIAID awarded the institute a five-year, $25 million contract in late 2001 to establish the center.

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