PNEUMOCOCCUS GENOME SEQUENCE COMPLETED
A University of Illinois at Chicago biologist is part of a team that has successfully sequenced the complete genome of a virulent strain of pneumococcus. The discovery may prove useful in combating this often-deadly bacterium that has grown resistant in recent years to antibiotics such as penicillin. The accomplishment was reported in the July 20 issue of Science.
Donald Morrison, UIC professor of biological sciences and a specialist in the study of pneumococcus, is a co-author who acted as an expert consultant in the sequencing work. The sequencing was performed by the Rockville, Md.-based Institute for Genomic Research.
The strain is a clinical isolate of the bacterium Streptococcus pneumoniae, or pneumococcus, taken from the blood of a 30-year-old Norwegian male. Researchers describe the strain as highly invasive and virulent in a mouse model of infection.
Pneumococcus is the most common cause of acute respiratory and ear infections. Researchers estimate that over 3 million children die every year worldwide from pneumococcus-triggered pneumonia, bacteremia or meningitis.
In the United States, penicillin is the most commonly used antibiotic in keeping pneumococcus under control. But Morrison warned of the bacterium's ability to breed resistance to penicillin and other antibiotics.
"Pneumococcus is carried by one-third or more of the population," said Morrison. "We are relying mainly on penicillin to control it, but it's becoming more and more resistant. So we are in a race to discover better ways to treat it before it discovers better ways to get around current treatments."
With newer technologies and sophisticated genetic sequencing techniques playing a big role, Morrison said the complete sequencing of this genome might help researchers win that race.
In the past, biology students would spend years writing Ph.D. dissertations on sequences of single genes within pneumococcus. Now there's a complete model openly available to researchers. The newly released genome contains 2,326 sequenced genes.
"The sequence now is just a matter of looking up something on a computer screen," said Morrison. "This means we can now get back to doing biology, rather than doing sequencing and gene-finding. The experiments on the organism are the important, fun stuff."
What is so interesting about pneumococcus? "It's very good at finding DNA around it, taking it in and inserting it into its genome," said Morrison. "It does essentially what you could think of as self-administered, natural gene therapy. We are studying how the bacterium does that."
While the research may prove helpful in developing new therapies for controlling pneumococcus, it may also provide some clues on how gene therapy, in general, can be improved.
"If this organism, which does gene insertion with an efficiency that's close to 100 percent, can reveal some of its secrets," said Morrison, "maybe we can use those secrets to improve gene therapy for other purposes to get to a higher level of efficiency as well."
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