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Updated: Jul 20, 2026
A Mouse Model for Pathogen-induced Chronic Inflammation at Local and Systemic Sites
Published on: August 8, 2014
Comparison of inflammatory changes caused by Porphyromonas gingivalis with distinct fimA genotypes in a mouse abscess
K Nakano1, M Kuboniwa, I Nakagawa
1Department of Pediatric Dentistry, Osaka University Graduate School of Dentistry, Osaka, Japan. nakano@dent.osaka-u.ac.jp
Abstract:
The fimA gene of Porphyromonas gingivalis, encoding fimbrillin (a subunit protein of fimbriae) has been classified into six genotypes (types I-V and Ib). The genotypic variation was previously suggested to be related to the severity of adult periodontitis in the general population. In this study, we compared inflammatory changes caused by bacterial infection to study pathogenic heterogeneity among the different fimA strains in a mouse abscess model. Bacterial suspensions of 13 P. gingivalis strains representing the six fimA types were subcutaneously injected into female BALB/c mice, and serum sialic acid concentrations were assayed as a quantitative host inflammatory parameter. Type II fimA organisms caused the most significant induction of serum sialic acid, as well as other infectious symptoms, followed by types Ib, IV and V. In contrast, types I and III caused weak inflammatory changes. In addition, fimA mutants of type II strains clearly lost their infectious ability. These findings suggest that fimA genotypic variation affects expression of P. gingivalis virulence.
Insights
Porphyromonas gingivalis fimA gene variations influence virulence. Type II fimA strains caused the most severe inflammation and infection symptoms in mice, suggesting genotypic differences impact P. gingivalis pathogenicity.
Area of Science:
- Microbiology
- Immunology
- Genetics
Background:
- The fimA gene of Porphyromonas gingivalis encodes fimbrillin, a key component of fimbriae.
- Six genotypes (types I-V and Ib) of the fimA gene exist.
- Genotypic variation in fimA has been linked to adult periodontitis severity.
Purpose of the Study:
- To investigate the pathogenic heterogeneity among different fimA genotypes of P. gingivalis.
- To compare inflammatory responses induced by various fimA strains in a mouse model.
Main Methods:
- Thirteen P. gingivalis strains representing six fimA types were used.
- Bacterial suspensions were subcutaneously injected into female BALB/c mice.
- Serum sialic acid concentrations were measured as a host inflammatory marker.
Main Results:
- Type II fimA strains induced the most significant increase in serum sialic acid and infectious symptoms.
- Types Ib, IV, and V also showed notable inflammatory responses.
- Types I and III fimA strains elicited weak inflammatory changes.
- fimA mutants of type II strains exhibited reduced infectious ability.
Conclusions:
- fimA genotypic variation significantly affects the expression of P. gingivalis virulence.
- Specific fimA genotypes, particularly type II, are associated with increased pathogenicity and host inflammatory responses.
