Human serum antibodies against Bacteroides intermedius. Antigenic heterogeneity impairs the interpretation of the host response

RAPD fingerprinting for the distinction ofPrevotella intermediasensu stricto fromPrevotella nigrescens

A collection of 70 oral strains including reference strains and clinical isolates identified as Prevotella intermedia sensu lato was constituted to cover a large clinical and geographical diversity. Electrophoresis of the enzyme malate dehydrogenase allowed the identification of the 70 study strains as Prevotella intermedia sensu stricto (n= 36), Prevotella nigrescens (n= 31) and three unclassified strains. By using four primers, DNA fingerprints were generated from 20 strains as random amplified polymorphic DNA (RAPD). Matching co-migrating amplicon positions by pairwise comparison allowed the clustering of the fingerprints as two groups coincident with the P. intermedia/P. nigrescens assignment by enzyme electrophoresis of malate dehydrogenase. Our data suggest that isolates identified asP. intermedia sensu lato by conventional criteria can be speciated asP. intermedia sensu stricto or P. nigrescens by RAPD fingerprinting.

PCR-DNA probe assays for identification and detection of Prevotella intermedia sensu stricto and Prevotella nigrescens

The purpose of this study was to construct PCR-DNA probe assays specific for Prevotella intermedia sensu stricto and Prevotella nigrescens based on the ability of randomly amplified polymorphic DNA (RAPD) fingerprinting to generate species-specific markers. The strategy included four steps: (i) construction of first-generation DNA probes from a 850-bp RAPD marker for P. intermedia sensu stricto and a 1,300-bp RAPD marker for P. nigrescens, (ii) cloning and sequencing of each RAPD marker, (iii) designing of primer pairs flanking specific internal sequences of 754 bp for P. intermedia sensu stricto and of ca. 1,100 bp for P. nigrescens, and (iv) synthesis (by PCR amplification) and digoxigenin labeling of quantities of DNA probes 754 and ca. 1,100 bp in size. The PCR-DNA probe assays combine either PCR amplification of a 754-bp specific sequence in the genomic DNA of strains of P. intermedia sensu stricto and hybridization with the 754-bp digoxigenin-labeled probe or amplification of a ca. 1,100-bp sequence of P. nigrescens and hybridization with the ca. 1,100-bp probe. Specific hybridization was observed with the amplified DNAs from 25 strains of P. intermedia and 24 strains of P. nigrescens, and no reaction was observed with the PCR products from 20 foreign species. The PCR-DNA probe assays described here should allow a highly specific and sensitive detection of P. intermedia sensu stricto and P. nigrescens in mixed infections.

Serum immunoglobulin G antibodies to Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Streptococcus sanguis during experimental gingivitis in young adults

Twenty-eight young, healthy adults completed an experimental gingivitis study in which blood and clinical recordings were obtained at baseline; after a 4-week period of thorough oral hygiene; after a subsequent 3-week period of plaque accumulation; and after another 2 weeks of thorough oral hygiene. Serum immunoglobulin G antibodies against whole cells of Porphyromonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum and Streptococcus sanguis were determined using enzyme-linked immunosorbent assay. Mean serum immunoglobulin G antibody levels to P. intermedia, F. nucleatum and S. sanguis remained essentially constant during the experiment, whereas the immunoglobulin G antibodies to P. gingivalis declined during the initial period of oral hygiene and the subsequent period of plaque accumulation to an average of 84.5% of the baseline value. This reduction could be attributed to the people who developed marked gingival inflammation during the period of plaque accumulation, indicating that the systemic host response may be associated with local tissue responses to variations in oral hygiene. These people were, however, also characterized by higher initial serum immunoglobulin G responses to P. gingivalis than people who developed less pronounced gingival inflammation during the experiment. The variability and individuality noted in the host response to potential pathogens have important implications for attempts to use such measures for establishing a diagnosis or prognosis for the individual patient.

Humoral antibody responses in periodontal disease

Several forms of periodontal disease are considered to be infectious diseases with associated specific bacteria. This study examined the humoral antibody levels as assayed by ELISA to Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Prevotella intermedia in adult periodontitis (AP), localized juvenile periodontitis (LJP), rapidly progressive periodontitis (RPP), and in periodontally healthy subjects (HS). Sixty-two of the 64 (96.9%) patients had significantly elevated antibody levels to at least one of the three organisms. Elevated levels of antibodies to P. gingivalis occurred in 82.8% of the RPP, LJP, and AP patients with all 3 disease groups showing greater responses than HS controls. Antibodies to A. actinomycetemcomitans were found in 59.4% of the RPP, LJP, and AP patients and were significantly higher in both LJP and RPP patients. Only 21.9% of the RPP, LJP, and AP patients showed elevated levels to P. intermedia with only significantly higher levels in the RPP and LJP groups. Antibodies to A. actinomycetemcomitans and P. intermedia were rarely found alone (only 5.1% and 2.6% of the patients respectively) but were usually accompanied by P. gingivalis. These results suggest that one or more combinations of these 3 bacteria may play a role in the pathogenesis of these forms of periodontal disease.

Specific antibody responses to subgingival plaque bacteria as aids to the diagnosis and prognosis of destructive periodontitis

We have reviewed the recent literature on the humoral immune responses to a variety of subgingival plaque bacterial species in patients with destructive periodontal diseases. We do not feel that the information presently available on the specific antibody responses to proposed pathogens such as Bacteroides gingivalis and Actinobacillus actinomycetemcomitans allows antibody responses to be diagnostic. All control subjects without periodontal destruction have antibodies to candidate pathogens but the generally higher levels in patients are not sufficiently elevated to be diagnostic. Nor can they be used to predict the initiation of disease or the onset of new episodes of destruction where disease had previously occurred. Successful treatment of patients may lead to lower levels of antibodies to some organisms, including possible pathogens, and thus support a given species in the aetiopathogenesis of disease. It appears that unsuccessful treatment may be accompanied by continuing high antibody levels to some organisms and further studies may enable this observation to be used to monitor therapy. There is some evidence from serological studies that each destructive episode may be induced by a different bacterial species or consortium. The start of studies using single antigens and the techniques of molecular biology will provide not only antibody-based diagnostic methods but also allow us to determine which bacterial antigens are virulence factors and thus the role of the antibody responses, whether protective or damaging, in the periodontal diseases.

Biochemical and serological characterization of Bacteroides intermedius strains isolated from the deep periodontal pocket

Fifty-one fluorescence-positive black-pigmented Bacteroides strains obtained from 51 patients with deep periodontal pockets (greater than 6 mm) were identified and characterized. Fifty of these strains were presumptively identified as Bacteroides intermedius according to the indole reaction. This was confirmed by further biochemical characterization. The 50 strains from diseased sites were then compared with 16 B. intermedius strains isolated from periodontally healthy individuals with no signs of destructive periodontal disease. Tests for antimicrobial susceptibility showed similar patterns for all 50 pocket-derived strains, except for one beta-lactamase-positive strain that was resistant to penicillin G and ampicillin. Forty-seven strains were tested for binding of three monoclonal antibodies defining three distinct serogroups of B. intermedius. Thirty-one strains belonged to serogroup I, three to serogroup II and thirteen to serogroup III. In comparison to the strains from the shallow periodontal pockets, serogroup I was significantly overrepresented in the patient group with periodontal disease. We conclude that saccharolytic black-pigmented Bacteroides species from deep periodontal pockets constituted, with very rare exceptions, a biochemically homogeneous but antigenically heterogeneous group of B. intermedius and that serogroup I is predominantly found in deep periodontal lesions.