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.
The version of the P. gingivalis genome released today is available on
the Comprehensive Microbial Resource web site at http://www.tigr.org/CMR.
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.