Prevention, Diagnosis and Treatment of Periodontal Disease Based on Genetic Analysis of Periodontopathogens.

对牙龈卟啉单胞菌（拟杆菌）的菌毛、血凝素和外膜蛋白等毒力因子的功能和基因进行了研究。在pUC质粒和特异性表达载体上克隆了编码纤维主要亚基蛋白（纤原蛋白）的fimA基因的上下游区域。利用噬菌体T7 RNA聚合酶/启动子表达载体系统，鉴定了下游区编码的分子量为50和80千酮的蛋白。Western blot分析结果表明，这两种蛋白作为次要成分似乎与菌毛有关。一个血凝素定位在整个包膜以均匀形式纯化。正如我们所推测的那样，纯化的血凝素具有巯基蛋白酶活性。编码该双功能物质的基因的n端部分在pUC19中被克隆。我们正试图克隆该基因的c端部分，并对整个基因进行测序，以估计该物质的主要结构。已克隆出该生物主要免疫显性表面蛋白（75k蛋白）的编码基因。该基因的DNA测序正在进行中，工作已进入收尾阶段。

Virulence factors such as fimbriae, hemagglutinin and an outer membrane protein from porphyromonas (Bacteroides) gingivalis have been studied as to their functions and genes. Downstream and upstream regions from the fimA gene which encodes a major subunit protein (fimbrilin) of fimbriae were cloned in pUC plasmids and a specific expression vector. Proteins with molecular masses of 50- and 80-kilodaltone, encoded by the downstream region were identified by using the bacteriophage T7 RNA polymerase/promoter expression vector system. The two proteins seemed to be associated with fimbriae as minor components based upon the results obtained by Western blot analysis. A hemagglutinin localized in whole envelope of this organism was purified in a homogeneous form. The purified hemagglutinin possessed a thiol protease activity as we have speculated. An N-terminal portion of the gene encoding this bifunctional material was cloned in pUC19. We are trying to clone a C-terminal portion of the gene and to sequence the entire gene in order to estimate the primary structure of this material. The gene encoding a major immunodominant surface protein (the 7 5K protein) of this organism has been cloned. DNA sequencing of the gene is in progress and the work is in the finishing touch.