CONFIRMATION OF THE SPECIES PREVOTELLA-INTERMEDIA AND PREVOTELLA-NIGRESCENS

The elevation of the two genotypes of Prevotella intermedia to species rank as P. intermedia and Prevotella nigrescens has increased the nee d for reliable differentiation between the two taxa. In this study, 53 strains, including strains whose species affiliations were known as w ell as fresh dental plaque isolates, were subjected to a multilocus en zyme electrophoretic analysis, DNA analyses in which we used whole gen omic DNA, rRNA sequences, and an oligonucleotide specific for the form er P. intermedia genotype II (P. nigrescens) as probes, and a sodium d odecyl sulfate-polyacrylamide gel electrophoresis analysis of soluble cellular proteins. All of these tests consistently separated the strai ns into the same two distinct groups corresponding to P. intermedia an d P. nigrescens, confirming that the two species constitute two distin ct populations Of bacteria. Each of the tests used independently provi ded reliable identification to the species level. A previously reporte d heterogeneity in the pattern of human immunoglobulin Al (IgA1) degra dation was not confirmed, No differences between species were observed , All of the strains induced total degradation of IgA1 within 48 h, a property that may be a virulence factor in periodontal disease develop ment. The enzymes responsible for IgA1 degradation were not inactivate d by the physiological proteinase inhibitors alpha(2)-macroglobulin an d alpha(1)-proteinase inhibitor.