INTRAINDIVIDUAL AND INTERINDIVIDUAL COMPARISON OF PORPHYROMONAS-GINGIVALIS GENOTYPES

Genetic analysis of 31 clinical strains of Porphyromonas gingivalis is olated from nine subjects, 2-6 strains per subject, was performed by S outhern hybridization. Chromosomal DNA was extracted by the method of Moncla et al. [1] and digested to completion with restriction endonucl eases PstI, ClaI and BglI. The DNA fragments were separated electropho retically on agarose gels, transferred to nylon membranes and hybridiz ed to the non-radioactively labelled plasmid pKK 3535 which contains t he rrnB ribosomal RNA operon of the Escherichia coli chromosome. Of th e three enzymes, BglI was the most suitable for the genetic analysis o f P. gingivalis. With this enzyme, the intra-individual strains were s hown to be identical in eight of the nine subjects, whereas inter-indi vidual strains were different.