Heterogeneity of Porphyromonas gingivalis strains on fimbrillin gene locus by restriction fragment length polymorphism analysis.

The adherence of Porphyromonas gingivalis (P. gingivalis) to the periodontal tissue may be an initial step in the pathogenesis of periodontal disease, and fimbriae is believed to play an important role in such processes. However, the heterogeneity of the size, sequence and antigenic reactivity of the fimbriae have been reported. The aim of the present study was to investigate the heterogeneity of P. gingivalis strains on the fimbrillin gene locus by RFLPs analysis. Fourty-seven P. gingivalis strains including 5 reference strains were used in this study. The plasmid (pUC13Bg 12.1) with the insert of fimA381 was modified with bisulfite and used as the probe. The genomic DNAs from P. gingivalis were digested with the restriction endonuclease SacI and PstI, electrophoresed, transferred and hybridized with the DNA probe. All Sac I digests generated one major band and the band size was almost the same (ca 2.5-kb), except strain W50. The Pst I digests showed one or two major bands and could be divided into 9 groups based on the band patterns. Moreover, isolates from one patient showed different band patterns. By RFLPs analysis, genetic heterogeneity seems to exist within the fimbrillin gene locus of P. gingivalis strains. Such genetic heterogeneity may reflect the previously reported difference of P. gingivalis fimbriae and moreover a single patient could be infected with more than one genotype of P. gingivalis.