Synergistic Roles of Fimbriae and Gingipain Genotypes in Porphyromonas gingivalis and Their Association With Periodontitis Severity.

Abstract

Objective: Porphyromonas gingivalis is a major periodontal pathogen periodontitis, with virulence mediated by fimbriae and gingipains. Differences in virulence may influence disease severity. This study aimed to assess the association and co-occurrence of fimbriae and gingipain genotypes and their relationship with clinical severity in periodontitis.

Materials and methods: This secondary analysis included 120 subgingival plaque samples from patients with periodontitis. Fimbriae (fimA types I-V) and gingipain (kgp, rgpA) genotypes were identified using PCR and restriction enzyme digestion, and P. gingivalis load was quantified by real-time PCR. Associations between genotypes and clinical parameters (probing depth and clinical attachment loss) were evaluated using Spearman's correlation and chi-square tests. Binary logistic regression assessed the association between periodontal disease severity and the presence of a combined virulence genotype, reported as odds ratios (ORs).

Results: The fimA types II and III and gingipain genotypes kgp-I and kgp-II were significantly associated with deeper PD and greater CAL (p  < 0.05). fimA type II was the most prevalent across all bacterial load percentiles, followed by type IV. kgp-I and rgpA type A were correlated with higher P. gingivalis counts. Significant positive correlations were observed between fimbriae and gingipain genotypes (p  < 0.05). Patients with CAL ≥5 mm had significantly higher odds of harboring the combined virulence genotype than those with CAL <5 mm (OR = 3.56; 95% CI: 1.43-8.47; p = 0.011).

Conclusion: Specific fimbriae and gingipain genotypes co-occur and are linked to increased bacterial load suggesting synergistic roles in the pathogenicity of P. gingivalis. The findings support the hypothesis that these virulence factors act synergistically to influence disease severity.

Clinical relevance: The integration of microbial virulence profiling with host immune response characterization may improve risk stratification and enable the development of personalized periodontal care strategies. Furthermore, microbial genotypic profiling may support the identification of disease-specific targets, thereby facilitating the implementation of tailored therapeutic interventions for effective periodontitis management.