Polymerase chain reaction and an outer membrane protein gene probe for the detection of Porphyromonas gingivalis.

A sensitivity assay for Porphyromonas gingivalis based upon the polymerase chain reaction (PCR) was developed. A 426-bp sequence, including a DraI-HincII DNA fragment (278 bp) encoding the 40-kDa outer membrane protein of the P. gingivalis gene was amplified. PCR products were obtained from chromosomal DNAs of the P. gingivalis strains tested but not from those of other oral microorganisms. The lower limit of template DNA detection was 10 pg with 30 cycles and 100 fg with 40 cycles of PCR by agarose gel electrophoresis. The PCR products were hybridized with DraI-HincII DNA fragment internal to the PCR primers regions used. The lower limit of hybridization detection was 10 pg and 10 fg of template DNA with 30 and 40 cycles of PCR, respectively. These results demonstrated the simplicity, rapidity and specificity of the procedure, as well as the use of the DraI-HincII DNA fragment in the identification of P. gingivalis.