Diversity of Lactobacilli Associated with Severe Early Childhood Caries

描述（由申请人提供）：本申请的长期目标是揭示一组被称为乳酸菌（Lb）的细菌的特征，该细菌在儿童和成人龋齿的进展和严重程度中起关键作用。近一个世纪以来，龋齿和Lb之间的联系是已知的，但在描绘100多种乳酸菌中哪一种负责龋齿的进一步进展仍然难以捉摸。遗传方法的最新进展和十几个Lb基因组的发表，使人们有可能对Lb成员亚群和导致龋齿的致龋性状有重要的了解。这些目标将通过两个具体目标来实现。目的1：对三组儿童进行Lb人群调查，一组是严重早期儿童龋（S-ECC），另一组是无龋（CF）组，另一组是中度活跃龋（白斑病变，WSL）组。我们将通过培养独立和培养依赖的方法来实现这些目标，以获得Lb种群的丰度和多样性的估计。我们还将通过AP-PCR鉴定在三组中发现的单个Lb基因型。Lb物种的独特基因型鉴定将通过16S rRNA基因测序来完成，以获得代表S-ECC， WSL和CF生境或生态位特征的不同物种/基因型的分离物集合。目的2是确定与龋生态位相关的遗传属性。将全基因组测序和比较基因组学应用于Aim 1分离株，结合公共和私人数据库中可获得的非口腔Lb基因组序列，将鉴定出龋齿/无龋齿生态位特有的遗传特征。有了这些信息，临床医生将能够分析口腔中的细菌样本，并确定Lb是否会导致龋齿。反过来，这将使临床医生对龋齿的风险和严重程度进行估计。这些发现的一个重要成果将为评估Lb作为健康相关益生菌的致龋潜力铺平道路。

DESCRIPTION (provided by applicant): The long-term objective of this application is to uncover the characteristics of a group of bacteria called the lactobacilli (Lb) that play a key role in the progression and severity of dental caries in both children and adults. For almost a century, the link between caries and Lb was known, but further progress in delineating which of the more than 100 species of lactobacilli were responsible for dental caries remained elusive. Recent advances in genetic methods and the publication of a dozen Lb genomes now make it possible to gain important insight into the sub-group of Lb members and the cariogenic traits responsible for caries. These goals will be met by two specific aims. Aim 1 is to conduct a survey of the Lb populations in three groups of children, those with severe early childhood caries (S-ECC) and two comparison groups, a caries free (CF) and a moderately active caries (white spot lesion, WSL) group. We will accomplish these aims by both culture-independent and culture-dependent methods to obtain estimates of abundance and diversity of the Lb populations. We will also identify individual Lb genotypes found in the three groups by AP-PCR. Lb species identification of unique genotypes will be accomplished by 16S rRNA gene sequencing to obtain a collection of isolates that represent the different species/genotypes that characterize the S-ECC, WSL, and CF habitat or niche. Aim 2 is to identify genetic attributes associated with the caries-niche. A combination of whole-genome sequencing and comparative genomics applied to the isolates derived from Aim 1, coupled with non-oral Lb genome sequences available in public and private database, will result in the identification of genetic signatures unique to the caries/caries-free niche. With this information, clinicians will be able to analyze a bacterial sample from the mouth and determine whether the Lb present are cariogenic or not. This, in turn, will give clinicians an estimation of risk for, and severity of, dental caries. An important spin off to these findings will pave the way toward assessing the cariogenic potential of Lb proposed as health-associated probiotics.