Utilizing PCR, the 16S rRNA detection rates for Porphyromonas gingivalis, Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Treponema denticola, and Campylobacter rectus in samples of stenotic coronary artery plaques were determined to be 21.6, 23.3, 5.9, 23.5, and 15.7%, respectively. The detection rates for P. gingivalis and C. rectus correlated with their presence in subgingival plaque.

One major pathogenic factor of Porphyromonas gingivalis is Arg-gingipain (Rgp), an arginine-specific cysteine proteinase. To clarify the effect of rgpA DNA vaccine, we immunized BALB/c mice via the abdomen with a Gene Gun or via the nasal cavity weekly for 6 weeks. After immunization, the mice were challenged orally with P. gingivalis. Immunization elicited IgG responses against P. gingivalis in both groups. Nasal immunization also induced sIgA against P. gingivalis, although Gene Gun immunization did not. Reduction of alveolar bone loss was observed in both groups at 42 days following initial infection. This effect was more pronounced in the intranasal immunization group than in the Gene Gun group. The results of this study suggest that immunization with rgpA DNA vaccine via the nasal cavity is an effective method for preventing alveolar bone loss incurred by infection with P. gingivalis.

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