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

（1997财政年度）通过CAT分析，发现gtfB基因的转录水平在之前克隆的s.a mutans基因中最高。除此之外，还证实了Tween 80存在时gtfB基因的转录激活。（1998财政年度）虽然试图从龋齿较少的人收集的唾液中分离出可感染变形链球菌的噬菌体，但尝试失败了。在化脓性链球菌染色体DNA数据库中寻找与噬菌体基因同源的基因，并将所得基因作为探针。分离出了10株似乎被噬菌体感染的变形链球菌。（1999财政年度）对去年分离的10株S.mutans进行了噬菌体诱导试验。然而，即使在任何条件下，也无法诱导噬菌体。制备了变形链球菌在Tween 80存在或不存在时生长的细菌细胞裂解液。研究了是否存在能与gtfB基因启动子区相互作用的物质。结果发现，通过结合gtfB基因启动子上游区域来调节转录水平的因子在Tween 80的存在下被诱导。（2000财政年度）由于S.mutans Xc表达自溶酶活性，因此尝试克隆该活性编码基因。结果分离出一个与葡萄球菌自溶酶基因同源的基因。此外，一个基因簇类似于编码噬菌体成分的基因，已经在不及格区域的其他链球菌中发现。这些结果表明，编码变形链球菌自溶酶的染色体区域应该与噬菌体溶原的区域一致。

(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.