Aggregatibacter actinomycetemcomitans - Induced bone loss and antibody response in three rat strains

Background: The aimof this study is to compare the colonization, immunoglobulin (Ig)G response, and alveolar bone loss in Aggregatibacter actinomycetemcomitans (Aa)-inoculated Fawn Hooded Hypertensive (FHH), Dahl Salt-Sensitive (DSS), and Brown Norway (BN) rats. Methods: Each rat strain was divided into wild-type Aainoculated and non-inoculated control groups. Blood taken at 12 weeks after inoculation was assessed for Aa-specific IgG antibodies by an enzyme-linked immunosorbent assay. Colonization was assessed 12 weeks postinoculation. Bone loss was estimated bymeasuring the distance from the cemento-enamel junction (CEJ) to the alveolar bone crest (ABC) at 20 molar sites. Colonization and antibody levels were compared by using the Student t test. Diseased ratsweredefinedas having twosites per quadrant with CEJ-ABC distances that were significantly greater than the control CEJ-ABC distances. Results: The Aa colonization of FHH rats was significantly higher than in other strains (P <0.05). The Aa-specific IgG levels in theDSS Aa-inoculated groupwere significantly higher than in its control group (P <0.05). Only FHH rats showed Aa diseaseassociated bone loss (P = 0.0021). Conclusions: Aa colonized and caused more disease in FHH rats than in the other rat strains. The rat strains each responded differently to the same Aa strain.