Scientists Sequence Genome Of Major Periodontal Disease Bacterium

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.

The version of the P. gingivalis genome released today is available on the Comprehensive Microbial Resource web site at http://www.tigr.org/tigr-scripts/CMR2/CMRHomePage.spl. The genome has been provisionally annotated, meaning that the products of most genes within the genome, including many responsible for virulence and growth, are listed. Later this month, the P. gingivalis genome will also be posted on a new Oral Pathogens Database being created by the Los Alamos National Laboratory with support from the NIDCR.

The P. gingivalis genome project was led by Dr. Robert Fleischmann at TIGR. Working with Dr. Fleischmann were Drs. Margaret Duncan and Floyd Dewhirst at The Forsyth Institute. Additional information on the P. gingivalis genome project can be found at http://www.pgingivalis.org.

The NIDCR is a component of the National Institutes of Health (NIH) in Bethesda, MD. The Institute is the nation's leading supporter of research on oral, dental, and craniofacial health. NIH is an agency of the U.S. Department of Health and Human Services.