Molecular analyses and identifications of new genes to infectious diseases relating with oral biofilm

在细菌感染性疾病如龋齿中，生物膜的形成与细菌致病性和逃避免疫效应有关。许多研究者在体外实验中间接地研究了口腔生物膜的形成机制，这与口腔状况不同。在本研究中，我们试图在与口腔相似的条件下鉴定变形链球菌生物膜形成的易感基因。在此基础上，我们进一步分析了该基因的表达与宿主基因（e2f-1）的关系。首次研究了变形链球菌临床菌株在流动细胞系统中形成生物膜的强度与基因表达的比较。通过脉冲场凝胶电泳，从3岁儿童及其母亲的生物膜样本中分离出17种不同的基因组DNA模式。在共聚焦激光扫描显微镜（CLSM）下，菌株FSC-3和FSC-4在流动细胞系统上形成生物膜的能力不同，分别表现出最高和最低的生物膜形成水平。此外，在FSC-3和-4生物膜的比较中，DNA微阵列结果显示74个基因的差异表达超过4倍。我们在群体感应（QS）系统中鉴定了74个csp诱导基因的60%以上，包括杆菌肽转运atp结合蛋白bcrA和PTS系统IIA， B， C和d。分析发现，bcrA缺陷菌株与野生菌株相比，E2F-1^<-/->小鼠牙表面生物膜的形成和附着显著减少。结果表明，这些基因可能与宿主体内的E2F-1基因相互作用，并参与生物膜的形成。

A biofilm forming is associated with bacterial pathogenicity and escape from immunological effects in bacterial infectious diseases such as dental caries. Many investigators studied indirectly mechanism of oral biofilm in vitro assay, which is not similar to oral condition. In the present study, we attempted to identify susceptible genes for biofilm formation of Streptococcus mutans in similar condition to oral cavity. Further, we analyzed relationship between the gene expression and host gene (e2f-1) that response to byposalivation in mouse. Comparison of the intensity of biofilm formation by S.mutans clinical strains in flow cell system with the gene expression was firstly investigated. Seventeen different patterns of genomic DNA were identified in S.mutans organisms isolated from biofilm samples taken from 3-year-old children and their mothers by pulsed-field gel electrophoresis. The S.mutans isolates showed differing abilities to form biofilms on flow cell system and the FSC-3 and FSC-4 strains showed the greatest and least, respectively, levels of biofilm formation when examined with confocal laser scanning microscopy (CLSM). Further, in a comparison of FSC-3 and -4 biofilms, DNA microarray results showed 74 genes were differentially expressed more than 4-fold. We identified more than 60% CSP-induced genes of 74 in quorum sensing (QS) system, including bacitracin transport ATP-binding protein bcrA and PTS system IIA, B, C and D. Analyses of the bcrA deficient strains showed significant deceasing of biofilm formation and attachment on the tooth surface in E2F-1^<-/-> mouse in comparison with wild strain. Our results showed that these genes may play biofilm formation and interact with E2F-1 gene in host.