Antigenic characteristics and serological identification of 10 black-pigmented Bacteroides species

The number of direct repeats in hagA is variable among Porphyromonas gingivalis strains

The coding sequence for the surface protein hemagglutinin A (HagA) of Porphyromonas gingivalis 381 has previously been shown to contain four direct 1.35-kb repeats, designated repHA. This study was performed to determine if the number of repHA units in hagA is consistently 4 or if allelic polymorphism exists among strains and/or upon multiple passage of P. gingivalis. To this end, primers which were homologous to the regions directly 5' and 3' of the repeat domain in hagA were synthesized. PCR conditions which allowed amplification of the 8.4-kb repeat region between the primers in P. gingivalis 381 were established. Genomic DNA templates from 13 other P. gingivalis strains and 9 fresh clinical isolates from patients were analyzed under the same conditions as used above. Analysis of these PCR products demonstrated that the strains tested had different numbers (two to four) of repHA units in the respective hagA genes. The PCR products of 8.4, 7.0, and 5.7 kb represent four, three, and two repeats, respectively. One strain from each group (381, four repeats; W83, three repeats; and AJW4, two repeats) was also tested to determine if the number of repeats remained invariant upon passaging onto solid medium. No variability in the number of repeats in hagA within a strain was detected after 18 passages. P. gingivalis 381 was chosen for further testing in a mouse abscess model to determine if conditions of in vivo growth would select for deletions or duplications of the repeated sequences. Five days after infection, no change in the number of repeats was detected in cells recovered from either nonimmunized or preimmunized mice. This data indicates an interstrain variability of the number of repeat units and hence a size variability of the HagA protein of P. gingivalis, but unlike some surface antigens of other pathogenic species, the number of repeats remains relatively stable given the conditions of growth tested here.

Serum antibodies to Porphyromonas gingivalis in children

Serum samples from 41 periodontally healthy children aged 1 to 16 years were examined by ELISA for the presence of antibodies against a glass bead-EDTA cell surface extract (GBE) and LPS of Porphyromonas gingivalis strain ATCC 33277. P. gingivalis was detected by immunofluorescence, using a species-specific monoclonal antibody, in 41% (17/41) of the children, and isolated from a single subject (2.4%). IgM, IgG, and IgA against GBE were detected in respectively 39/41 (95%), 41/41 (100%), and 27/41 (66%) of the sera. In 22/39 sera, the IgG titer was below 50% that of a reference pool of adult sera (RP). In 13/41, the IgM titer was higher than that of the RP, mostly in the deciduous dentition group. Detectable IgA titers were always below 67% that of the RP. A polarized distribution of the children appeared, separating 21 non- and low IgA responders (IgA titer below 10% that of the RP) from the remaining 20 subjects. Anti-LPS IgG, IgM, and IgA were detected in 41/41 (100%), 39/41 (95%), and 23/38 (61%) respectively of the children. In 32/41 sera, the anti-LPS IgG titer was below 50% that of the RP, while in 20/39 sera, IgM titers were higher. A clearcut dichotomy in IgA response was observed, allowing us to distinguish non-IgA responders (39%) and IgA responders to LPS (61%). Our results indicate that serum antibodies to P. gingivalis are highly prevalent in children, suggesting that an active primary immune response and a secondary immune response are well underway.(ABSTRACT TRUNCATED AT 250 WORDS)

The lipopolysaccharide of Porphyromonas gingivalis is not antigenically cross-reactive with that of other species

Large numbers of Porphyromonas, Prevotella, and Bacteroides strains were screened by 3 monoclonal antibodies (MAbs) and 8 rabbit antisera raised against Porphyromonas gingivalis, in order to detect any possible recognition of non-P. gingivalis surface antigens by these immunoreagents. All three MAbs, which were LPS-specific, extensively recognized LPS from 10 P. gingivalis strains in immunoblotting, whereas they recognized none of the 34 non-P. gingivalis strains. Rabbit antisera were similarly specific for P. gingivalis cells in immunofluorescence and with LPS in grid-blotting, but several of them recognized LPS from one Prevotella melaninogenica and 5 Prevotella intermedia strains in Western blotting. Since several pre-immune sera and an irrelevant serum raised to a Streptococcus species recognized up to 5 of these preparations, we exclude that the reactions were due to antigens shared by P. gingivalis and Prevotella. Rather, we consider that they were false-positive reactions due to natural antibodies, stimulated in a non-specific manner upon immunization with P. gingivalis, in animals whose immune systems were sensitized to Prevotella species before immunization.

K-antigens in Porphyromonas gingivalis are associated with virulence

We investigated antigens in spreading and non-spreading Porphyromonas gingivalis strains. On the basis of differences in virulence in the mouse model, 8 strains were selected for antiserum production in rabbits. Hyperimmune sera were tested by double immunoprecipitation and immunoelectrophoresis. Besides a common antigen, differences in antigenic composition were observed in the thermolabile antigens between all strains tested. Two different heat-stable antigens were found after heating at 120 degrees C. One such antigen was detected after sonication of the pellet fraction of autoclaved P. gingivalis cells. This antigen cross-reacted with 6 of the 8 immune sera. This somatic antigen was almost neutrally charged and sensitive to sodium periodate treatment, suggestive of lipopolysaccharide. A second heat-stable antigen was detected in the supernatant of autoclaved strains of W83, W50, HG184 and A7A1-28. These non-somatic antigens were strain-specific, i.e., no cross-reactivity was found with heterologous hyperimmune sera. An exception was strain W50, which had a non-somatic heat-stable antigen which was recognized by W83 antiserum. These antigens were resistant to DNAse, RNAse and proteinase-K treatment but were degraded by sodium periodate. In immunoelectrophoresis, these antigens appeared to be negatively charged. These properties are characteristics of a K-antigen, which likely represent a thermostable carbohydrate capsule. The presence of K-antigen correlates very well with the serum resistance, the low chemiluminescence, the resistance to phagocytosis and the need for opsonization with specific antibodies for complement-mediated killing of virulent P. gingivalis strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Serum IgG reactive with oral anaerobic microorganisms associated with infections of endodontic origin

Numerous species of bacteria have been implicated with infections of endodontic origin. The purpose of this study was to compare the levels of serum IgG antibodies reactive with a panel of 10 oral anaerobic microorganisms implicated in infections of endodontic origin. Serum samples were collected from 4 patient groups that included healthy patients without endodontic or periodontal disease, patients with chronic adult periodontal disease, patients with endodontic disease and patients with combined endodontic-periodontal disease. When Prevotella intermedia was allowed to react with sera from the 4 patient groups, significant pairwise differences were shown between the healthy group and each of the other 3 groups. In addition, there was a significant difference between the periodontal disease group and the combined endodontic-periodontal disease group. When Porphyromonas gingivalis was allowed to react with sera from the 4 patient groups, significant pairwise differences were shown between the healthy group and the periodontal disease group, the healthy group and the combined endodontic-periodontal disease group, the endodontic disease group and the periodontal disease group and the endodontic disease group and the combined endodontic-periodontal disease group. The results of this investigation support other studies that associate P. intermedia with both endodontic disease and chronic adult periodontal disease. The results also support studies that implicate P. gingivalis as a periodontopathogen.

Serological studies of Porphyromonas (Bacteroides) gingivalis and correlation with enzyme activity

Porphyromonas gingivalis from the human oral cavity was serologically characterized using absorbed and unabsorbed rabbit antisera. The reference strains were ATCC 33277, W50, W83, 381 and hara 1. The 432 isolates were from periodontal pockets of 63 patients with adult periodontitis. Using sonicated antigens, four serotypes were identified by immunodiffusion tests and immunoelectrophoresis. Each patient harbored only one serotype of P. gingivalis, and serotypes I and IV predominated. The incidence of serotype I was four times higher than that of serotype II, and approximately seven times higher than that of serotype III. The collagenolytic and some proteolytic enzymes of representatives of each serotype were assessed. Although all strains produced these enzymes to some degree, some differences in their levels were observed. Serotype II strains were more collagenolytic than serotypes I or III, and serotype III exhibited lower activities of N-CBz-glycyl-glycyl-arginyl peptidase than other serotypes. Antibiotic sensitivity was also compared with antimicrobial disks, and serotype IV strains exhibited high sensitivity to the four antibiotics used.

Factors in virulence expression and their role in periodontal disease pathogenesis

The classic progression of the development of periodontitis with its associated formation of an inflammatory lesion is characterized by a highly reproducible microbiological progression of a Gram-positive microbiota to a highly pathogenic Gram-negative one. While this Gram-negative microbiota is estimated to consist of at least 300 different microbial species, it appears to consist of a very limited number of microbial species that are involved in the destruction of periodontal diseases. Among these "putative periodontopathic species" are members of the genera Porphyromonas, Bacteroides, Fusobacterium, Wolinella, Actinobacillus, Capnocytophaga, and Eikenella. While members of the genera Actinomyces and Streptococcus may not be directly involved in the microbial progression, these species do appear to be essential to the construction of the network of microbial species that comprise both the subgingival plaque matrix. The temporal fluctuation (emergence/disappearance) of members of this microbiota from the developing lesion appears to depend upon the physical interaction of the periodontal pocket inhabitants, as well as the utilization of the metabolic end-products of the respective species intimately involved in the disease progression. A concerted action of the end-products of prokaryotic metabolism and the destruction of host tissues through the action of a large number of excreted proteolytic enzymes from several of these periodontopathogens contribute directly to the periodontal disease process.(ABSTRACT TRUNCATED AT 250 WORDS)

Protective efficacy of active and passive immunizations against experimental infection with Bacteroides gingivalis in ligated hamsters

The protective efficacy of immunization against Bacteroides gingivalis infection was examined in hamsters. Whole cells or extracted hemagglutinin of B. gingivalis 381 was injected with incomplete Freund adjuvant into the inguinal regions of hamsters. Two weeks after the rats received a booster injection, cotton threads were tied coronally to the gingival margins of the mandibular first molars, and then a streptomycin-resistant B. gingivalis 381R' strain was inoculated into the rats' oral cavities. The subcutaneous immunizations resulted in slight reductions in the numbers of B. gingivalis on the ligature threads compared with the sham-immunized group. Peroral administration of whole cells of B. gingivalis to hamsters elicited salivary immunoglobulin responses, but no reduction of B. gingivalis 381R' colonization was found in this group. Repeated passive immunizations with rabbit antiserum to B. gingivalis into the oral cavities of the hamsters resulted in a reduction in the number of organisms in the periodontal region.

Biology of asaccharolytic black-pigmented Bacteroides species

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Bacteroides gingivalis, Bacteroides intermedius and Actinobacillus actinomycetemcomitans in human periodontal diseases

Bacteroides gingivalis, Bacteroides intermedius and Actinobacillus actinomycetemcomitans seem to be major pathogens in advancing periodontitis in man. First, these organisms are recovered in higher prevalence and proportions from progressive periodontitis lesions than from quiescent periodontal sites. Second, antibody levels against B. gingivalis and A. actinomycetemcomitans are markedly elevated in serum and gingival crevice fluid of periodontitis patients compared to normal controls. Third, B. gingivalis and B. intermedius elaborate potent proteases and A. actinomycetemcomitans various noxious substances which have the potential to perturb important host defenses and to disintegrate key constituents of the periodontal tissues. Monitoring these bacteria in advanced periodontal lesions may greatly assist the assessment of treatment efficacy and risk of further periodontal breakdown.

Antigenic heterogeneity of non-pigmented Bacteroides species isolated from the human oral cavity

Serological studies on 27 strains of non-pigmented Bacteroides isolated from the human oral cavity revealed multiple serotypes within B. buccae. B. capillus (= B. buccae) and B. pentosaceus (= B. buccae) were found to be serogroups within B. buccae. B. denticola possessed cross-reactive antigens with B. buccae. Tested strains of B. oralis, B. veroralis, B. oris, and B. heparinolyticus were clearly differentiated from each other.