Newland J W, Neill R J
Walter Reed Army Institute of Research, Washington, D.C. 20307.
J Clin Microbiol. 1988 Jul;26(7):1292-7. doi: 10.1128/jcm.26.7.1292-1297.1988.
A set of DNA probes has been developed to study the genes for Shiga-like toxins (SLT) and the bacteriophage from which these toxin genes were isolated. Under stringent conditions of hybridization (80 to 90% homology), these probes detect strains containing (i) SLT I-related genes, (ii) SLT II-related genes, (iii) phage sequences from the SLT I-converting phage H19A/933J, and (iv) phage sequences from the SLT II-converting phage 933W. Strain characterization by hybridization with the toxin gene probes was as accurate as methods that used toxin-specific antibody to determine toxin synthesis. Screening of different gram-negative bacteria with the toxin probes revealed that only two species carry sequences related to the SLT genes, Escherichia coli and Shigella dysenteriae 1. These results indicated that the lower levels of toxin activity observed in shigellae other than S. dysenteriae 1 are due to a gene(s) that is genetically distinct from that which encodes Shiga toxin. Analysis of enterotoxigenic, enteroinvasive, enteropathogenic, and enterohemorrhagic E. coli indicated that SLT genes are found primarily in the enterohemorrhagic E. coli strain group. Use of both the toxin and the phage probes has identified a variety of genotypic combinations of phage and toxin sequences which differ from those observed for the original toxin-converting phage isolates, for E. coli O157:H7 strain 933, and for E. coli O26:H11 strain H19.
已开发出一组DNA探针，用于研究志贺样毒素（SLT）基因以及分离出这些毒素基因的噬菌体。在严格的杂交条件下（同源性为80%至90%），这些探针可检测出含有以下基因的菌株：（i）与SLT I相关的基因；（ii）与SLT II相关的基因；（iii）来自将SLT I转化的噬菌体H19A/933J的噬菌体序列；（iv）来自将SLT II转化的噬菌体933W的噬菌体序列。通过与毒素基因探针杂交进行菌株鉴定，其准确性与使用毒素特异性抗体来确定毒素合成的方法相当。用毒素探针筛选不同的革兰氏阴性菌发现，只有两种菌携带与SLT基因相关的序列，即大肠杆菌和痢疾志贺氏菌1型。这些结果表明，在痢疾志贺氏菌1型以外的志贺氏菌中观察到的较低水平的毒素活性，是由于一个与编码志贺毒素的基因在遗传上不同的基因。对产肠毒素性、肠侵袭性、肠致病性和肠出血性大肠杆菌的分析表明，SLT基因主要存在于肠出血性大肠杆菌菌株组中。同时使用毒素和噬菌体探针，已鉴定出多种噬菌体和毒素序列的基因型组合，这些组合与最初的毒素转化噬菌体分离株、大肠杆菌O157:H7菌株933以及大肠杆菌O26:H11菌株H19中观察到的不同。
