Differential virulence and innate immune interactions of Type I and II fimbrial genotypes of Porphyromonas gingivalis.
BACKGROUND
The fimA-encoded fimbriae of the periodontal pathogen Porphyromonas gingivalis display genetic diversity. Type I fimbriated P. gingivalis (Pg-I) has been most widely studied at the molecular level, whereas Pg-II is the most frequent isolate from severe periodontitis.


METHODS
To investigate virulence differences between Types I and II fimbriae, we examined strains 33277 (Pg-I) and OMZ314 (Pg-II), reciprocal swap mutants (i.e. expressing the heterologous fimbrial type), and their respective FimA-deficient derivatives. These organisms were tested in a mouse periodontitis model and in interactions with mouse macrophages, a cell type that plays important roles in chronic infections.


RESULTS
Strain 33277 induced significantly more periodontal bone loss than OMZ314 and substitution of Type II fimbriae with Type I in OMZ314 resulted in a more virulent strain than the parent organism. However, the presence of Type II fimbriae was associated with increased proinflammatory and invasive activities in macrophages.


CONCLUSIONS
The inverse relationship between proinflammatory potential and ability to cause experimental periodontitis may suggest that an aggressive phenotype could provoke a host response that would compromise the persistence of the pathogen.
Wang
M
M
Department of Periodontics/Oral Health and Systemic Disease, University of Louisville School of Dentistry, Louisville, KY 40292, USA.
Liang
S
S
Hosur
K B
KB
Domon
H
H
Yoshimura
F
F
Amano
A
A
Hajishengallis
G
G
D016301:Alveolar Bone Loss / Q000276:immunology / Q000382:microbiology; D000818:Animals; D002478:Cells, Cultured; D036781:Fimbriae Proteins / Q000235:genetics*; D010861:Fimbriae, Bacterial / Q000235:genetics* / Q000276:immunology; D007113:Immunity, Innate / Q000235:genetics; D008264:Macrophages / Q000276:immunology; D051379:Mice; D008807:Mice, Inbred BALB C; D010518:Periodontitis / Q000276:immunology / Q000382:microbiology*; D010587:Phagocytosis; D016966:Porphyromonas gingivalis / Q000235:genetics* / Q000276:immunology; D037521:Virulence Factors / Q000235:genetics*
D037521:Virulence Factors; C063055:fimbrillin; D036781:Fimbriae Proteins