Vic, Your guesses about me have never been right, so why started discussing false info? You've have a PhD from U Penn since 1990 and have experince in vaccines and now you have graduated to monoclonals, my specialty, but lets just say you are scientically trained and should be able to help the readers understand that the sequencing of the attack Ames identified a very interesting locus that can be used to distnguish several Ames isolates and this intersting locus is IDENTICAL in the attack Ames and the Ames from USAMRIID.
Martin Enserink
Science Magazine, 10 May, 2002
Seven months after anthrax letters hit U.S. media and government offices, investigators still haven't nabbed a suspect--and the genome project launched in part to help them seems unlikely to provide a break either. An analysis of the genome of the strain used in the attacks, published online this week by Science (www.sciencexpress.org), has yielded extra tools for fingerprinting the hundreds of different anthrax strains, but little in the paper suggests that it can help the FBI tie the attack strain to a specific lab.
"I don't see how this could help us much," says Barbara Hatch Rosenberg, director of the Federation of American Scientists' Chemical and Biological Arms Control Program, who has closely watched the federal investigation. But even without an immediate payoff, researchers at The Institute for Genomic Research (TIGR) in Rockville, Maryland, who conducted the research, say it provided experience in comparing microbial genomes that could be useful in future outbreaks.
Last fall's letters contained spores of a Bacillus anthracis strain called Ames, which was collected from a dead cow in Texas in 1981, sent to the U.S. Army Medical Research Institute of Infectious Diseases in Fort Detrick, Maryland, and later forwarded for experiments to some 14 other labs.
Because microbes mutate whenever they grow, it's possible that the current strain at each lab is a little different from the rest. And if one of them happens to match the attack strain, now dubbed Florida, it might lead to the bioterrorists. But until recently, genetic fingerprinting studies by Paul Keim's lab at Northern Arizona University in Flagstaff had looked at diversity at just several dozen markers, rather than the entire genome, and these had failed to discriminate among different Ames isolates.
Now, TIGR's Timothy Read, Keim, and others have sequenced the entire Florida strain and compared it with the so-called Porton strain, whose genome TIGR had already sequenced. (A paper describing that genome is due out later this year.) Like most strains, the Florida strain contains two extra rings of DNA, called plasmids, that the Porton strain lacks, so the researchers compared their sequences with the plasmids from two other strains. In all, the team found 53 places where the Florida genome differed from the Porton strain and the two previously sequenced plasmids.
But could these apparent genetic hotspots also help tell apart other, previously indistinguishable anthrax strains? To find out, the researchers took four Ames isolates collected from various labs; another Ames strain from a dead goat in Texas; and two non-Ames strains found in cattle. For each strain, they determined the exact sequence at each of the 53 markers.
Although the markers could clearly distinguish the samples from dead animals, they did a poor job of discriminating among the four lab strains. One had 36 copies of the nucleotide A where others had only 35--an almost meaningless difference. Another had 37 copies at that same spot; but that strain also lacked one of the plasmids, making it easy to tell apart anyway. At all the other markers, the four lab strains and the Florida strain were identical. Theoretically, more variation may emerge when the Ames strains from all 15 labs are put through the same 53-marker test. But the scant differences found so far "offer only slim hope that something useful will come out," says Rosenberg. Still, says Keim, the study shows that full-genome sequencing could be a useful forensic tool. And in cases such as bioterror crimes, the price tag--some $125,000 for a bug's genome--is hardly an issue: "A lawyer's sneeze costs more than that."