esearchers said yesterday that they had found subtle differences among samples of the same anthrax strain, increasing hopes of identifying the laboratory that might have been the source of the microbes used in last fall's anthrax mailings.Posted on 05/09/2002 11:31:36 PM PDT by JohnHuang2
esearchers said yesterday that they had found subtle differences among samples of the same anthrax strain, increasing hopes of identifying the laboratory that might have been the source of the microbes used in last fall's anthrax mailings.
The scientists, who work at the Institute for Genomic Research in Rockville, Md., said it would take only a few weeks to complete some tests on samples that the Federal Bureau of Investigation had collected from research laboratories that possess the Ames strain of anthrax, the type used in the mailings.
Scientists at the institute say it is negotiating with the F.B.I. for a contract to analyze the bureau's collection of Ames samples. A law enforcement official said the institute's analysis "has already gone through one round and we've provided them with other samples that are closer to the origin for comparison."
Dr. Timothy Read, a researcher at the institute, has worked for several years to decode the genome of the anthrax bacterium, choosing an Ames strain of anthrax that came from the British biological-warfare laboratory at Porton Down.
After the anthrax mailings last fall, the Institute for Genomic Research was also asked by the National Science Foundation to sequence the DNA of anthrax bacteria isolated from Robert Stevens, who died after exposure to anthrax in the American Media International building in Boca Raton, Fla.
In a report in today's issue of Science, Dr. Read and colleagues said they had identified roughly 60 sites on the anthrax genome at which the Stevens isolate and the Porton Down isolate had one or more different DNA units.
The issue now is whether a DNA test, similar to those in forensic cases, can be developed for the anthrax bacterium and used to identify the laboratory most likely to have provided the microbes that killed Mr. Stevens and the other victims.
Some 15 laboratories are known to possess or have worked with the Ames strain. The F.B.I. sent out subpoenas in February asking for Ames anthrax samples and presumably now has a reasonably complete collection for analysis.
Dr. Steven Salzberg, a bioinformatics expert at the institute, said it had found many more DNA differences between the two Ames isolates it analyzed than some experts had expected. On this basis Dr. Salzberg expressed confidence that an analysis of the F.B.I.'s sample collection would show which was closest to bacteria that infected Mr. Stevens.
"We would first test these 60 markers," he said, referring to the sites of variability the institute found, "and then look for additional markers and would be able to rule out some labs pretty quickly."
Development of a DNA test for the Ames strain will not be simple. The many strains of anthrax found worldwide are remarkably similar because of the bacterium's degree of genetic stability. It reproduces by dividing into two cells that are generally identical except for occasional errors made in copying the parent cell's DNA.
So the chances of finding DNA differences among the stocks of Ames anthrax at different laboratories did not seem promising at first. Of the 60 sites of variation found by the institute, only one was useful in distinguishing between the Ames anthrax samples possessed by four laboratories, designated as A, B, C and D.
The anthrax genome consists of a single large chromosome and two small circles of DNA, called plasmids, that carry extra genes. At a point on the second plasmid, the DNA consists of a string of A or adenine units, one of the four bases of DNA.
The bacterium isolated from Mr. Stevens has a string of 35 A's at this site, the same as the isolates from Laboratories B and C but different from Laboratory A, with 37 adenines, and Laboratory D, with 30.
The four laboratories' data was first announced in February by Dr. Paul Keim of Northern Arizona University, a colleague of the institute's team and a rival for the F.B.I.'s attention. Dr. Keim had identified the plasmid site of variability because the two anthrax plasmids had previously been decoded at the Los Alamos National Laboratory.
Working under contract for the F.B.I., Dr. Keim had samples of Ames anthrax from the four unidentified laboratories and tested the 60 sites of variation found by the institute. He is a coauthor with the institute's researchers of the Science article.
Dr. Keim has not found any more such points of distinction, according to scientists at the institute who say their method — decoding the entire anthrax genome — will bring to light all differences that may exist between laboratory samples.
Institute researchers decoded the Stevens and Porton Down genomes without F.B.I. money but kept the agency informed of its progress. Dr. Claire Fraser, the institute's president, said that when an F.B.I. team visited it, "I was very impressed with their knowledge of genomics and forensics."
Anthrax Found on Fed's Mail
WASHINGTON, May 9 — The Federal Reserve said that about 20 pieces of its mail had tested positive for traces of anthrax.
Daniel L. Mihalko, the United States postal inspector, said the positive readings could have resulted from cross-contamination.
In December, anthrax was detected on mail to the Federal Reserve, but follow-up tests yielded no further signs of the bacteria.
FYI.
Clues to Anthrax Attacks Found
Gotta thank Mr. Shane for bursting the balloon about that recent claim of "two types" or such being new news. It's over two years old.
As far as I can tell, this article does not say that differences were found among the attack anthrax samples. It just says that there are differences among the various reference samples of Ames. This is why the attack samples can be compared to the reference samples to tell which reference sample is the closest genetically.
The new statement is that there were two slightly-different genetic types mixed in the samples of the attack anthrax. This is a very different statement.
Now, according to Shane's recent article, this was discovered quite some time ago, but I do not believe there was any public announcement of this until the recent article.
Disclaimer: Opinions posted on Free Republic are those of the individual posters and do not necessarily represent the opinion of Free Republic or its management. All materials posted herein are protected by copyright law and the exemption for fair use of copyrighted works.