Effect Of Gbp-A And Antibody Against Gbp-A On Adhesion Of Streptococcus Mutans

Dental caries is one of the three chief non-contagious diseaseswhich threaten the human health. Mutans streptococci (MS) are the primary cariogenic agents, and Streptococcus mutans (S. mutans) are believed to have the closest relationship with human caries. At present, studies on anticaries mainly focus on a series of events involving the adherence, accumulation and proliferation of MS on tooth surfaces. The surface proteins (such as Agl/II, GTFs, et al) are the very important factors contributing to the adherence and accumulation of MS on tooth surfaces. In the past two decades, more and more attention was paid to one category of surface proteins-glucan-binding proteins (Gbps), because they served as a "bridge" between bacteria and the matrix of dental plaque. Now the Glucan-binding domain (GBD) of GbpA of S. mutans has been cloned, expressed and purified. But there has not been any report about the effect of the GBD of GbpA and its antibody on the adherence and accumulation of different Streptococcus mutans. And neither has there been any report about the detection of the GBD of GbpA of S. mutans in children's saliva. This study consists of two parts:3H-TDR. In the first experiment, hydroxyapatite was coated with solution of different concentrations of the GBD of GbpA. Then the two strains of S. mutans were incubated with the hydroxyapatite. In the second experiment, the two strains of S. mutans labeled by 3H-TDR were incubated with saliva-coated-hydroxyapatite and different concentrations of the antibody against the GBD of GbpA. Samples were assayed by using liquid scintillation counter, and binding abilities of the strains were evaluated by the count per minute (cpm). The results indicated that the GBD of GbpA could promote and enhance the adhesion of the two strains of S. mutans, and the antibody against the GBD of GbpA could inhibit the adhesion of the two strains of S. mutans.2. Based on the condition (dmfs) of their teeth, 100 children at the age of 4 or 5 were divided into 3 groups. Their saliva from the mouth was collected. The method of Western blotting was used to detect the level of the GBD of GbpA in the children's saliva. The results indicated that the level of the GBD of GbpA in the children's saliva was closely associated with the condition (dmfs) of their teeth. The higher the number of dmfs, the higher the level of the GBD of GbpA in the children's saliva.