Pathogenic factors of cell adherent Escherichia coli

用细菌性腹泻病分离菌株研究了肠致病性大肠杆菌的粘附特性和细胞毒性。当用我们发明的一种新的检测方法检查时，一些菌株粘附在人类组织培养细胞上。用电子显微镜观察了这些细菌细胞的表面特性和生物活性。不同H型荷叶的超微结构各不相同，并对其超微结构与H型荷叶超微结构的关系进行了重新分析和评述。从一个新的角度研究了残链的自组装模式。这些菌株的菌毛的超微结构与以往的报道没有明显的区别，但其中一些菌株同时缺乏MS和MR血凝。该菌毛似乎编码了60Kb的质粒，目前正在进行分子克隆。菌株对Vero、HEp-2和HeLa细胞的细胞毒活性较弱，但活性易受不确定因素的影响。从出血性结肠炎中分离的氧梭菌中也检测到类似的活性，并分析了毒素的性质。毒素似乎编码了30Kb的质粒，基因的表征正在进行中。通过建立病原菌遗传分析技术和设备，成功克隆了气荚膜荚膜梭菌的-毒素（气荚膜溶血素）和-毒素（磷脂酶C），因其具有较强的D - Nase活性而未能克隆。建立了梭状芽孢杆菌的基因文库，并对梭状芽孢杆菌的其他致病胞外酶进行了广泛的检测。利用不同产肠毒素能力的菌株，研究了热不稳定肠毒素基因表达的调控。人们怀疑毒素的产生量应该在转录水平上受到调节。

The adherence properties and cytotoxicity of enteropathogenic Escherichia coli have been studied with isolated strains from bacterial diarrhea diseases. Some of the strains adhered to tissue cultre cells of humans origin when checked by a new method of the assay that we invented. The surface properties of those bacterial cells were examined by electronmicroscopy as well as biological activities. The ultrastructure of fragella was varied in each H type and the correlation between the structure and the types were re-examined and reviewed. A new aspect on the mode of self assembly of fragellines was proposed. The ultrastructure of fimbriae of those strains were not distinguishable with previous reports but some of them lacked for both MS and MR hemoagglutination. The fimbriae seemed to be coded for 60Kb plasmid and the molecular cloning is being undertaken. The strains had weak cytotoxic activities on Vero, HEp-2 and HeLa cells, but the activity was easy to be modified by uncertain factors. The similar activity was detected in K. oxytoca isolated from hemorrhagic colitis and we analyzed the properties of the toxin. The toxin seemed to be coded for 30Kb plasmid and the characterization of the gene is on the way. By establishing techniques and facilities for genetic analysis of pathogenic factors of bacteria, we succeeded in molecular cloning of -toxin ( perfringolysin ) and -toxin ( phospholipase C ) of clostridium perfringens of which gene cloning have been unsuccessful because of the hazards of clostridial strong D Nase activities. We established the gene library and the other pathoqenic extracellular enzymes of clostridium are extensively examined.The regulation of gene expression of heat labile enterotoxin was studied with the isolated etec strains which were varied in the productivity of the enterotoxin. It was suspected that the amount of the toxin production should be regulated at the level of transcription.