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International Journal of Dentistry
Volume 2012, Article ID 549169, 4 pages
Research Article

Pathogenicity of Treponema denticola Wild-Type and Mutant Strain Tested by an Active Mode of Periodontal Infection Using Microinjection

1Department of Molecular Genetics, The Forsyth Institute, Cambridge, MA 02142, USA
2Department of Oral Medicine, Infection and Immunity, Harvard School of Dental Medicine, Boston, MA 02115, USA

Received 24 February 2012; Accepted 7 March 2012

Academic Editor: Chaminda Jayampath Seneviratne

Copyright © 2012 Jacques Izard et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


The available passive mode of periodontal infections in mice requires high efficiency of bacterial attachment and invasiveness and is not always suitable to test the pathogenicity of genetically engineered mutant strains. We developed an active mode of oral infection, using microinjection in the marginal gingiva of mice, to test the pathogenicity of a genetically engineered Treponema denticola mutant strain deficient in intermediate-like filaments, compared to the wild-type strain. This targeted mode of infection inoculates the bacterial strain to be tested directly at a lesion site (needle entry point) located at the future periodontal lesion site. The efficiency of T. denticola wild-type strain to elicit bone loss contrasted with the lack of pathogenicity of the intermediate-like filament deficient mutant strain in comparison to the sham infection. The periodontal microinjection oral model in mice can be used for a variety of applications complementary to the passive mode of periodontal infection in context of pathogenicity testing.