IRON UTILIZATION BY BACTEROIDES GINGIVALIS

厌氧性口腔细菌，牙龈拟杆菌， 作为成人牙周炎的主要病原体。 营养需求是首要的 在B的本地化中的生态重要性。牙龈炎 裂缝区。 B。牙龈炎需要氯化血红素才能生长，但事实并非如此 其他铁化合物是否能满足这种营养需求。 本研究旨在确定铁获得的机制， 利用，并评估其在B致病性中的作用。牙龈炎 拟议项目的目标是确定铁的要求 的B。牙龈炎的体外生长，并将这些与体内生长相关。 铁源包括与转铁蛋白、乳铁蛋白、白蛋白结合的铁， 结合珠蛋白和血红素结合蛋白，通常在体内发现的来源。 的机制 将通过1）确定是否存在B. 牙龈炎可以利用其他生物产生的铁载体，2）如果B。 牙龈确实产生其自身的铁载体，和3）如果B。 牙龈炎产生特定的蛋白质，由铁的生长调节， 有限的条件。 将采取遗传学方法来检查更多 通过构建菌株B，密切结合铁的需要。牙龈 不同之处仅在于利用氯高铁血红素进行生长的能力。 Tn4351 将使用转座诱变来构建这些菌株。 将在我们的小鼠模型中使用同基因株来评估 这些菌株。 我们将克隆相应的铁利用基因 使用特异性Tn 4351-B。作为探针的牙龈突变体基因组DNA总量 基因组文库 此外，B.牙龈生长在铁充足， 将评价缺铁培养基引起感染的能力 在小鼠皮下腔室模型中。 这些研究将使 铁利用在B致病性中的作用的评价。 牙龈炎

The anaerobic oral bacterium, Bacteroides gingivalis, has been implicated as a major pathogen in adult periodontitis. Nutritional needs are of prime ecological importance in the localization of B. gingivalis to the gingival crevice area. B. gingivalis requires hemin for growth, however it is not known if other iron-compounds can fulfill this nutritional requirement. This study is designed to identify the mechanism of iron acquisition and utilization, and to assess their role in pathogenicity of B. gingivalis. The objectives of the proposed project are to define the iron requirements of B. gingivalis for growth in vitro and to relate these to growth in vivo. Iron sources will include iron bound to transferrin, lactoferrin, albumin, haptoglobin and hemopexin, sources commonly found in vivo. The mechanisms involved in iron acquisition will be examined by 1) determining if B. gingivalis can utilize siderophores produced by other organisms, 2) if B. gingivalis does indeed produce its own siderophores, and 3) if B. gingivalis produces specific proteins that are regulated by growth in iron- limited conditions. A genetic approach will be taken to examine more closely the requirement for iron, by constructing strains of B. gingivalis differing only in the ability to utilize hemin for growth. Tn4351 transpositional mutagenesis will be used to construct these strains. Isogenic strains will be used in our mouse model to assess the virulence of these strains. We will clone the corresponding genes for iron utilization using specific Tn4351-B. gingivalis mutant genomic DNA as probes in total genomic libraries. In addition, B. gingivalis grown in iron-sufficient and iron-deficient medium will be evaluated for its ability to cause infection in the mouse subcutaneous chamber model. These studies will allow for the evaluation of the role of iron utilization in the pathogenicity of B. gingivalis.