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Dextransucrase produced by Streptococcus mutans play an essential role in the formation of dental caries by synthesizing exopolysaccharides from sucrose, an important metabolite of the organism. In this study we report the location of dextransucrase in Streptococcus mutans cells and describe that antibodies raised against dextransucrase inhibited biofilm formation and reduced the adherence and hydrophobic properties of Streptococcus mutans. Western blot analysis and immunoelectron microscopy revealed that dextransucrase is located abundantly in the membrane fraction in S. mutans cells. Scanning electron microscopy and fluorescence microscopy revealed reduced cell density, impaired bioflim (plaque) formation in presence of dextransucrase antibodies. Genes associated with bioflim formation in S. mutans such as GtfB, GtfC, BrpA, relA, Smu630, vicK were down regulated (50–97%) in presence of the enzyme antibody. Presence of enzyme antibodies reduced adherence of S. mutans cells to glass surfaces by 58% and hydrophobicity by 55.2%. However dextransucrase antibodies did not affect acid production by S. mutans, under the experimental conditions. Immunohistochemistry studies with certain human samples displayed no cross reactivity with dextransucrase antibody. These findings suggest that antibodies against dextransucrase exhibit a profound inhibitory effect on the vital cariogenic factors of S. mutans and have no cross reactivity with human tissues tested, thus implying that dextransucrase could be a promising antigen to study its anticariogenic potential.

Introduction. Dextransucrase produced by Streptococcus mutans plays a vital role in the formation of dental caries by synthesizing exopolysaccharides from sucrose, which helps in the attachment of microbes to the tooth surface, causing caries. Exploring antibody production against S. mutans antigens could be an effective method to protect against dental caries. Hypothesis. Dextransucrase antibodies may help in the prevention of caries formation by inhibiting essential cariogenic factors. Aims. The aim of this study was to investigate the effects of dextransucrase antibodies on biofilm formation and certain associated cariogenic factors of S. mutans . Methodology. Dextransucrase was purified from culture of S. mutans . The antisera against the enzyme were raised in rabbits. The effect of dextransucrase antibodies on biofilm formation was studied using scanning electron microscopy, fluorescence microscopy and quantitative real-time polymerase chain reaction. The effects of the antibodies on associated cariogenic factors were examined using established methods. The cross-reactivity of antibodies with human lung, liver, heart, thyroid and kidney tissues was evaluated by immunohistochemistry. Results. Our findings showed impaired biofilm formation in S. mutans in the presence of dextransucrase antibodies. Genes associated with biofilm formation such as gtfB, gtfC, brpA, relA, Smu.630 and vicK were downregulated (50–97 %) by dextransucrase antibodies in S. mutans . The adherence of S. mutans to glass surface was reduced by 58 % and hydrophobicity was reduced by 55.2 % in the presence of the antibodies compared to the controls. Immunohistochemistry studies revealed no cross-reactivity of human tissues with dextransucrase antibodies. Conclusions. These findings suggest that antibodies raised against dextransucrase exhibit a profound inhibitory effect on biofilm formation and vital cariogenic factors of S. mutans , which supports the contention that dextransucrase could be a promising antigen to study for its anticariogenic potential.