Scientists sequence genome of major periodontal disease bacterium

6/12/2001  Scientists have sequenced the genome of Porphyromonas gingivalis, a bacterium believed to play a major role in adult periodontitis, or gum disease. It is the first oral disease-causing microbe to be completely sequenced. The annotated P. gingivalis sequence will be posted on the Internet today, making it freely available to researchers worldwide. The sequencing project, supported by the National Institute of Dental and Craniofacial Research (NIDCR), was carried out by scientists at The Institute for Genomic Research (TIGR) in Rockville, MD in collaboration with The Forsyth Institute in Boston, MA. "P. gingivalis is one of the most intensely studied dental pathogens," said Dennis Mangan, Ph.D., chief of NIDCR's Infectious Diseases and Immunity Branch. "There is a large cadre of researchers out there ready to use the sequence data to identify the genetic mechanisms for the organism's virulence and to develop better approaches for preventing or eradicating periodontitis." Periodontitis is a chronic infectious disease of the gums and underlying bony tissues. Untreated, it can destroy those tissues and result in tooth loss. By conservative estimate, more than 35 million Americans have periodontitis. The mouth is teeming with bacteria, most of which do not cause disease. But when the largely gram-positive community of bacteria that normally live in the spaces between the gums and teeth are displaced by gram-negative anaerobic bacteria, periodontitis sets in. A small number of gram-negative species are associated with specific forms of periodontitis; P.gingivalis is the organism associated with chronic and severe adult periodontitis. With the genetic blueprint for P. gingivalis in hand, dental researchers will be able to identify potential targets for periodontal vaccines and drug therapies. Currently the primary treatments for periodontitis are deep cleaning (scaling and root planing) and surgery. The P. gingivalis sequence also provides the scientific community at large with information on an organism from a major group of bacteria not previously sequenced: the bacteroides group of gram-negative anaerobes. The sequence, which contains 2.3 million DNA base pairs, will be valuable for comparative genomics and for advancing researchers' understanding of bacterial diversity. It will also enhance scientists' ability to find new gene targets for antibiotics that work on gram-negative anaerobes. These bacteria are naturally resistant to some antibiotics, and are acquiring resistance to many others. SOURCE: NIH/National Institute of Dental and Craniofacial Research

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