Counteractive therapy against the cariogenic bacterium by introduction of antisense-RNA of virulent genes

(The 1997财政年度）通过CAT分析比较，发现gtfB基因的转录水平在先前已克隆的变异链球菌基因中最高。除此之外，还证实了在吐温80存在下gtfB基因的转录激活。(The 1998财政年度），虽然尝试从龋齿经历较少的人收集的唾液中分离可感染变形链球菌的噬菌体，但该尝试失败。在化脓性链球菌染色体DNA数据库中搜索与噬菌体基因同源的基因，并将所得基因用作探针。分离出10株似乎被噬菌体感染的变形链球菌。(The 1999财政年度）对去年分离的10株变形链球菌进行了噬菌体诱导试验。然而，即使利用任何条件，也不可能诱导噬菌体。当变形链球菌在存在或不存在吐温80的情况下生长时，制备细菌细胞裂解物。检查是否存在能够与gtfB基因的启动子区相互作用的物质。发现在吐温80的存在下诱导通过结合到gtfB基因的启动子的上游区域来调节转录水平的因子。(The由于变形链球菌Xc表达自溶酶活性，因此尝试克隆编码该活性的基因。结果，分离出与该菌的自溶酶基因同源的基因。此外，一个基因簇，这是类似的，涉及基因编码的噬菌体成分已经确定在其他链球菌中的flunking区。这些结果表明，编码变形链球菌自溶酶的染色体区域与噬菌体溶原化的区域是一致的。

(The 1997 fiscal year)Transcriptional level of the gtfB gene was found to be highest among the S.mutans genes that had been cloned previously, when compared by CAT assay. In addition to this fact, the transcriptional activation of the gtfB gene in the presence of Tween 80 was confirmed.(The 1998 fiscal year)Though the bacteriophage infectable to S.mutans was tried to be isolated from the saliva collected from persons with fewer caries experience, the attempt was failed. The genes homologous to the bacteriophage gene were searched for the S.pyogenes chromosomal DNA database and the resulting gene was used as a probe. Ten strains of S.mutans which seem to be infected by a phage were isolated.(The 1999 fiscal year)On 10 strains of S.mutans, which had been isolated last year, the induction of phage was examined. However, it was impossible to induce the phage, even if any conditions were utilized. The bacterial cell lysate, when S.mutans grown in the presence or absence of Tween 80, was prepared. It was examined whether the substance which is able to interact with promoter region of the gtfB gene exists or not. It was found that the factor which adjusts the transcriptional level by binding to the upstream region of the promoter of the gtfB gene is induced in the presence of Tween 80.(The 2000 fiscal year)Since S.mutans Xc expressed the autolytic enzyme activity, the cloning of the gene coding for this activity was tried. As the result, a gene homologous to the autolytic enzyme gene of the staphylococcus was isolated. Furthermore, a gene cluster that is similar to that involving genes encoding the phage components already identified in other streptococci in the flunking region. These results suggested that the chromosomal region which encodes the autolytic enzyme of S.mutans was supposed to consist with the region where the phage lysogenizes.