Identification and Quantification of Archaea Involved in Periodontal Disease

Objectives: Archaea have been isolated from the human oral cavity, but have not been established as causes of human disease. To reveal the relationship between the periodontal diseases and the abundance of archaeal 16S rRNA genes in the subgingival plaque, Quantitative real-time PCR were applied for quantify methanogenic archaea in the plaque sample. Methods: Subgingival plaque were collected from 17 aggressive periodontitis, 25 patients with chronic periodontitis, 26 patients with plaque-induced gingivitis and 38 healthy control subjects. Qualitative and quantity of methanogenic archaea were examined by amplification of the 16S rRNA genes in the DNA extracted from the plaque samples followed by sequence analysis of the TA clone of amplified products. Results: Archaea were found to harbored by 52.9% of aggressive periodontitis patients and 56.0% of chronic periodontitis, 7.7% of ginginvitis and zero of healthy subjects. Quantity analysis showed the average abundance of archaeal 16S rRNA gene in archaea-positive patients were different between the three groups. An occurrence of 6.66*10⁶ 16S rDNA copy number from per µg wet plaque were detected in aggressive periodontitis sufferers, 4.47*10⁶ in chronic periodontits and 1.78*10⁶ in ginginvitis groups. Conclusion: The prevalence of archaea in periodontitis groups were significantly higher than that in gingivitis group (p<0.01). The average archaea 16S rRNA gene copy numbers were significantly higher in aggresive and chronic periodontitis patients compared to the gingivitis patients (p>0.01). This suggests that Archaea may be implicated as causative agents for periodontits.(Supported by National Natural Science Foundation of China. No.30700945)