To help find out who launched the first major bioterrorism attack in the United States, scientists have compared the DNA of the anthrax bacterium that killed a man in Florida last October with the DNA of a version of the bacterium commonly studied in laboratories. The comparison revealed only a few subtle genetic differences between the two strains. The analysis confirms that the Florida strain has the same origin as the laboratory version, but it doesn’t pinpoint a specific source.
Timothy D. Read of the Institute of Genomic Research (TIGR) in Rockville, Md., and his colleagues were already sequencing the DNA of Bacillus anthracis when letters containing spores of the anthrax bacterium started showing up last fall. The researchers then received government funding to quickly sequence the genome of the bacterial strain sent in the letters.
Like the B. anthracis originally studied by Read’s group, the Florida version appears to come from the so-called Ames strain, which researchers isolated from a dead Texas cow in 1981. It was originally investigated at a military research laboratory in Fort Detrick, Md., but was subsequently distributed to laboratories worldwide.
Since the genes in B. anthracis change little between generations, it’s hard to distinguish among descendants of the original Ames strain. In fact, Read’s group reports in an upcoming Science that there are only 11 small points of difference in the DNA sequences of the main chromosomes of the lethal Florida strain and the one TIGR was already studying.
Although the FBI didn’t specifically request TIGR’s help, Read and his colleagues have given their data to officials investigating the bioterrorism attacks. To create a resource that could help identify the source of a future bioterrorism attack or a natural outbreak of anthrax, TIGR now plans to decipher the entire genomes of more than a dozen other B. anthracis strains.