Bacterial Clonality and Risk for Periodontitis

描述（由申请人提供）：牙龈卟啉单胞菌是一种与牙周组织破坏有关的侵入性厌氧菌。虽然目前认为宿主反应有助于疾病进展，并可能决定疾病的模式和严重程度，但牙菌斑中特定细菌的毒力因子，包括牙龈卟啉卟啉菌，也有助于牙周疾病。牙龈卟啉卟啉菌侵入高度血管化的牙龈组织，使细菌能够获得铁源并避免宿主的免疫反应。我们观察到各种牙龈卟啉卟啉菌株的侵袭能力变化多达三个数量级。这很可能是由牙龈假单胞菌基因组上存在的遗传多态性来解释的。这种多态性反映了菌株间的异质性，可以使用基于全球基因组微阵列的分析来表征。使用这种基于微阵列的比较基因组杂交（CGH），我们之前已经分析了具有不同侵袭能力的牙龈假单胞菌的实验室菌株。该分析揭示了牙龈卟啉卟啉菌基因组中入侵相关基因的一个子集。我们还表明，牙龈卟啉单胞菌菌株存在于患病部位具有明显更大的侵袭效率比健康部位的牙龈卟啉单胞菌菌株。因此，我们这个项目的目标是筛选临床菌株，以确定编码入侵相关功能的基因与疾病之间是否存在直接联系。为此，我们将利用来自患病部位和牙周健康部位的牙龈假单胞菌菌株。我们的假设是，与入侵相关的细菌基因子集的存在可能与疾病的严重程度有关。我们的假设将通过以下方法得到验证：1)检测从患病和健康部位分离出来的临床牙龈卟噬菌是否存在入侵特异性基因；2)将特定入侵相关基因或基因组的存在与临床指标联系起来。识别独特的疾病相关毒力因子（疾病基因型）将有助于更好地了解这种生物体的遗传异质性，并能够设计用于慢性和侵袭性牙周炎风险评估和治疗的诊断工具。这种方法也有可能识别侵入性临床菌株和宿主组织之间的串扰。这些信息将进一步促进发展新的确定的分子方法治疗牙周炎。

DESCRIPTION (provided by applicant): Porphyromonas gingivalis is an invasive anaerobe implicated in periodontal tissue destruction. While it is currently considered that the host response contributes to disease progression and may dictate the pattern and severity of the disease, virulence factors of specific bacteria of the Dental plaque including P. gingivalis also contribute to periodontal pathoses. P. gingivalis invades the highly vascularized gingival tissues, which enables the bacterium to gain access to iron sources and to avoid the host immune response. We have observed that the invasive ability of various P. gingivalis strains varies by as much as three orders of magnitude. This is most likely explained by genetic polymorphisms present on the P. gingivalis genome. Such polymorphisms reflect inter-strain heterogeneity that can be characterized using global genomic microarray-based analysis. Using such microarray-based comparative genomic hybridization (CGH) we have previously analyzed laboratory strains of P. gingivalis that have diverse invasion abilities. This analysis revealed a subset of invasion-associated genes from the P. gingivalis genome. We have also shown that P. gingivalis strains present in diseased sites have significantly greater invasive efficiencies than P. gingivalis strains from healthy sites. Consequently, our goal for this project is to screen clinical strains in order to determine if there is a direct link between genes encoding invasion-associated functions and disease. For this, we will utilize P. gingivalis strains from diseased sites and from periodontal healthy sites. It is our hypothesis that the presence of an invasion-associated subset of bacterial genes can be linked with the severity of disease. Our hypothesis will be tested by 1) testing clinical P. gingivalis isolates from diseased and healthy sites for the presence/absence of invasion-specific genes, and 2) relating the presence of specific invasion-associated genes, or sets of genes, with the clinical indices. Identification of unique disease-associated virulence factors (disease genotype) will lead to a better understanding of the genetic heterogeneity of this organism and the ability to design diagnostic tools for risk assessment and therapies for chronic and aggressive periodontitis. This approach will also likely identify moieties involved in cross talk between invasive clinical strains and the host tissue. Such information will further facilitate the development of novel defined molecular approaches for the treatment of periodontitis.