Pathogenic factors of cell adherent Escherichia coli

以细菌性腹泻病分离株为研究对象，研究了致病性大肠埃希菌的黏附特性和细胞毒性。当用我们发明的一种新的检测方法进行检测时，一些菌株会附着在人类来源的组织培养细胞上。用电子显微镜观察细菌细胞的表面性质，并检测其生物活性。每种H型的脆体超微结构不同，并对其结构与类型的相关性进行了重新研究和综述。对碎屑分子的自组装方式提出了新的看法。这些菌株的菌毛超微结构与以前的报道没有区别，但其中一些菌株缺乏MS和MR血凝。菌毛似乎编码60kb的质粒，分子克隆正在进行中。该菌株对Vero、Hep-2和HeLa细胞具有较弱的细胞毒活性，但其活性易受不确定因素的影响。从出血性结肠炎分离的催产克雷伯菌中也检测到类似的活性，并对毒素的性质进行了分析。该毒素似乎编码了30Kb的质粒，该基因的特征正在进行中。通过建立细菌致病因子的遗传分析技术和设备，我们成功地克隆了产气荚膜梭菌的-毒素(产气荚膜溶血素)和-毒素(磷脂酶C)，但由于产气荚膜梭菌较强的D酶活性的危害，其基因克隆一直未成功。我们建立了基因文库，并对梭状芽孢杆菌的其他致病性胞外酶进行了广泛的检测。以分离的ETEC菌株为材料，研究了不同肠毒素产量的菌株对不耐热肠毒素基因表达的调控。有人怀疑毒素的产生量应该在转录水平上进行调节。

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.