Use of GtfB as a Diagnostic for Caries Activity

描述(由申请人提供)：本申请的总体目标是创建一种简单、快速、廉价的诊断测试，可在就诊期间用于在明显的龋损之前检测龋齿活动，以便在牙列发生永久性损害之前进行干预。这项应用的具体目标是临床验证GTFB作为唾液标记物在早期儿童龋病(ECC)流行人群中作为儿童龋齿活动标志物的临床有效性。这种方法是建立在对龋齿发病机制的深入了解基础上的。变形链球菌在牙齿表面定植时可分泌三种糖基转移酶(GTFB、GTFc和GTFD)。这些酶将饮食中的蔗糖裂解成其组成的单糖、葡萄糖和果糖，葡萄糖被聚合成可溶和不溶的葡聚糖，后者产生紧密附着的、富含细菌的生物膜，这是龋齿的特征，果糖被用作能源，产生溶解釉质的酸。GTFS在疾病进展中的核心作用使其成为活动性龋病的可信标记物。在最近的一项横断面临床试验中，鲍文实验室通过测量唾液中的GTFB水平，以约80%的诊断准确率区分患有ECC的儿童和没有疾病的儿童。有了这样一个有希望的开端，两个问题变得至关重要：1)GTFB免疫分析是否将成为前瞻性地识别龋齿活跃儿童的有效工具；2)如何在办公室环境中使用该方法的同时，优化该分析的临床性能。这个应用程序恰恰解决了这些问题。具体目标1的重点是一项100名患者的临床试验，以确定GTFB测量是否可以在儿童出现临床可检测到的龋损之前识别出患有龋病的儿童。临床上无龋齿的24-60个月的儿童将每三个月检查一次白斑病变或坦率的空洞，为期一年。同时采集唾液样本，测定GTFB。临床问题是：尚不清楚唾液GTFB升高是否预示着3个月、6个月或9个月后出现可检测到的龋损。具体目标2和3解决了创建额外的抗GTFB单抗和替代免疫分析形式，以便我们最终能够做出一种基于唾液的、快速、廉价的、无需仪器的早期龋齿诊断测试。公共卫生意义：使用GTFB作为龋病活动的诊断指标。龋齿仍然是发病率和费用的主要来源。仅在美国，每年就花费480亿美元来修复这种完全可以预防的疾病的后果。一种特别严重的形式，早期儿童龋病(ECC)在贫困的城市和农村人口中很常见，造成了卫生局局长报告中所说的无声流行病。在减轻龋齿负担所需的工具中，有一种简单、廉价、在岗的诊断测试，可以识别患有活动性龋齿的儿童，以便在他们的牙齿受到不可逆转的损害之前进行干预。诊断必须足够简单和快速，以便可以在儿科或牙科办公室使用。第一个目标是验证一种唾液传播的、病原体衍生的标记物，它是这种纵向测试中建议的分析物。

DESCRIPTION (provided by applicant): The over-arching objective of this application is the creation of a simple, rapid, inexpensive diagnostic test that can be used during an office visit to detect caries activity before overt carious lesions are apparent so that interventions can be made before permanent damage to the dentition occurs. The specific objective of this application is the clinical validation of an immunoassay measuring GtfB as a saliva-based marker for caries activity in children from a population where Early Childhood Caries (ECC) is prevalent. This method is predicated on an intimate understanding of the pathogenesis of Dental caries. Three glycosyltransferases (GtfB, GtfC and GtfD) are secreted by S. mutans when it colonizes the tooth surface. These enzymes cleave dietary sucrose into its constituent monosaccharides, glucose which is polymerized into soluble and insoluble glucans that create the tightly adherent, bacteria-rich biofilm that characterizes caries, and fructose which is utilized as an energy source and yields enamel-dissolving acids. The central role of Gtfs in disease progression makes them plausible markers for active caries. In a recent cross-sectional clinical trial, the Bowen laboratory distinguished children with ECC from disease-free children with about 80% diagnostic accuracy by measuring the levels of GtfB in their saliva. With such a promising start, two issues become paramount: 1) whether the GtfB immunoassay will be an effective tool for identifying caries-active children prospectively; and 2) ways by which the clinical performance of the assay can be optimized while the method is made useable in an office setting. This application addresses exactly these questions. The focus of Specific Aim 1 is a 100 patient clinical trial to determine whether GtfB measurement can identify children who have the disease Dental caries before they have clinically detectable carious lesions. Clinically caries-free children 24-60 months old will be examined for white spot lesions or frank cavitation every three months for a year. Saliva samples will be taken at the same time and GtfB measured. The clinical question will be: It is not clear whether elevated salivary GtfB values predict the emergence of detectable carious lesions 3, 6 or 9 months later. Specific Aims 2 and 3 address the creation of additional anti-GtfB monoclonal antibodies and alternative immunoassay formats so we can ultimately make a saliva-based, rapid, inexpensive, instrument-free diagnostic test for incipient Dental caries. Public Health Significance: Use of GtfB as a Diagnostic for Caries Activity. Dental caries remains a major source of morbidity and expense. In the United States alone, $48 billion are spent each year repairing the consequences of this completely preventable disease. A particularly severe form, Early Childhood Caries (ECC) is common in impoverished urban and rural populations creating what the Report of the Surgeon General called a silent epidemic. Among the tools needed for reducing the burden of Dental caries is a simple, inexpensive, in-office, diagnostic test that can identify children with active caries so that interventions can be made before their teeth become irreversibly damaged. The diagnostic must be simple and rapid enough that it can be used in a pediatric or Dental office. The first goal is to validate a saliva-borne, pathogen-derived marker that is the proposed analyte in such a longitudinal test.