Inhibitory effects of antibodies against cell surface protein antigen PAc-glucosyltransferase fusion proteins derived from Streptococcus mutans on the induction of dental caries

变形链球菌产生的细胞表面蛋白抗原（PAc）和葡萄糖基转移酶（GTFs）被认为是该生物的主要定植因子。本研究构建了PAc的唾液结合富丙氨酸区（PAcA）与催化蔗糖合成不水溶性葡聚糖的酶GTF-I的葡聚糖结合域（GB）融合蛋白PAcA-GB，以及PAcA与GTE-I的蔗糖结合域（SB）融合蛋白PAcA-SB。纯化了重组融合蛋白，制备了兔抗这些融合蛋白的抗体。抗paca - gb抗体明显抑制变形链球菌细胞相关和无细胞GTF制剂的不溶性葡聚糖合成，而抗PAcA-SB抗体则不明显抑制GTF- i的总葡聚糖合成。当在反应混合物中加入抗paca - gb抗体时，观察到变形链球菌对唾液包被的羟基磷灰石珠的蔗糖非依赖性和蔗糖依赖性粘附明显抑制。抗paca - sb抗体在没有蔗糖的情况下抑制变形链球菌对珠的粘附，而在有蔗糖的情况下则没有。融合蛋白PAcA-GB免疫可能有助于控制变形链球菌在牙齿上的定植。

Cell surface protein antigen (PAc) and glucosyltransferases (GTFs) produced by Streptococcus mutans are considered to be major colonization factors of the organism.In this study, fusion protein PAcA-GB, a fusion of the saliva-binding alanine-rich region (PAcA) of PAc with the glucan binding (GB) domain of GTF-I, an enzyme catalyzing the synthesis of water-insoluble glucan from sucrose, and fusion protein PAcA-SB, a fusion of PAcA with the sucrose binding (SB) domain of GTE-I were constructed. The recombinant fusion proteins were purified, and rabbit antibodies against these fusion proteins were prepared. Water-insoluble glucan synthesis by cell-associated and cell- free GTF preparations from S.mutans as well as total glucan synthesis by GTF-I was markedly inhibited by anti-PAcA-GB antibodies but not by anti- PAcA-SB antibodies. Significant inhibition of the sucrose-independent and sucrose-dependent adhesion of S.mutans to saliva-coated hydroxyapatite beads was observed when anti-PAcA-GB antibodies were added to the reaction mixture. Anti-PAcA-SB antibodies inhibited the adhesion of S.mutans to the beads in the absence of sucrose but not in the presence of sucrose. immunization with the fusion protein PAcA-GB may be useful for controlling the colonization of teeth by S.mutans.