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Anthrax: Scientists Learning Which Bacteria Strains Are More Deadly Scientists have learned more about what makes one strain of anthrax more virulent than another — information that could be used to make anthrax more dangerous or to help produce a more effective vaccine, the New York Times reported today (see GSN, March 26). Researchers at the Louisiana State University, the Lawrence Livermore National Laboratory and the U.S. Army Medical Research Institute of Infectious Diseases have found that each strain carries multiple sets of plasmids — which carry genes in addition to the bacterium’s large chromosome, according to the Times (see GSN, May 10, 2002). While it was previously believed that anthrax only contained one set of plasmids, the researchers discovered that each bacterium contains up to 243 copies of the first plasmid and up to 32 copies of the second, known as pX02. The presence of more copies of pX02 in an anthrax bacterium correlates to an increase in that strain’s virulence, the researchers said in their study, published in the current Journal of Clinical Microbiology. Subtle features of the anthrax’s DNA chromosome also appear to have an effect on virulence, they said. The study could help the genetic engineering of more deadly anthrax by increasing the number of pX02 plasmids, Pamala Coker of Lawrence Livermore, the study’s lead researcher, said. Martin Hugh-Jones, a member of the research team at LSU, said the study could also help explain why some anthrax vaccines are more effective than others. “This will allow us to do some very impressive things in coming on with new vaccines,” he said (William Broad, New York Times, March 27). For further information, see: CDC Frequently Asked Questions About Anthrax Journal of the American Medical Association Background on Anthrax
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