Resolution of quorum-sensing systems in dental plaque biofilm and development of the method that prevents the plaque formation by the control of them

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Dental plaque is the biofilm which is formed on the tooth surface, and is a protective barrier for the bacteria against the change of the environment, the antibiotic, and the host immune response. First this biofilm is formed by the extracellular polysaccharide(glucan), which the mitis group streptococci produce from sugar, and then is reinforced by the adhesive and water-insoluble glucan, which the mutans group streptococci produce. Dental plaque biofilm plays an important role in the caries formation. In this biofilm, the plaque bacteria communicate with other bacteria by the auto-inducer like hormone. By this communication system that is commonly known as quorum-sensing, the bacterial population density in the dental plaque is thought to be kept constant, and the bacterial mass against the host immune system is constructed.In this study, we analyzed gtfB, gtfC, gtfD, dexA, and b-galactosidase genes, using real-time RT-PCR based on the comparative CT method and demonstrated that three gtf and β-galactosidase genes were suppressed; however, dexA was upregulated. Thus, S. mutans could control biofilm mass by balancing glucan production and hydrolysis. Such control is necessary to maintain colonization on a smooth surface and to ensure that external carbohydrate present across the glucan layer is not used. On the other hand, the epitope assay of glycosyltransferase was performed and the anti-glycosyltransferase DNA vaccines were developed. Moreover, the change of the secretory IgA Secretion and the bacterial numbers in saliva by menstruation cycle were analyzed.