Blattner, research team leader and senior author, says one of the paper's major findings is the suggestion of a large bank of genes that may be exchanged across an entire family of bacteria, including related organisms like Salmonella, Shigella, the Plague-causing organism Yersinia, and the plant pathogen Erwinia. Blattner labeled this phenomenon a "pathosphere," which blurs the genetic lines between species.
"If the pathosphere is large enough, it could be an underlying factor in the emergence of new diseases," Blattner says. "We are already seeing this with the ability of some bacteria to develop antibiotic resistance. We need to be vigilant in finding the mechanisms that allow these pathogens to emerge."
The study implicates viruses as a key transfer mechanism for introducing virulent genes into E. coli. Some viruses, called bacteriophages, specifically target bacteria, and can carry with them a large amount of genetic baggage, pieces of which can cause disease, Blattner says.
There are currently no effective treatments for E. coli O157:H7, which causes a severe form of bloody diarrhea and can also release toxins that damage kidneys and cause renal failure. E. coli is found in the intestines of animals, including humans, and also exists in the field and in streams. The O157:H7, while rare, is probably the most dangerous to humans.
Perna says the sequencing accomplishment gives scientists a tangible set of targets for future work on drug treatments or vaccines. Researchers must first better understand how these different clusters of genes are being transferred horizontally across different species.
"One of the first things we can do is improve our detection and surveillance before it becomes a public health issue," she says. "We now have a far better distribution of genetic mark
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Contact: Nicole Perna
perna@ahabs.wisc.edu
608-262-0728
University of Wisconsin-Madison
23-Jan-2001