Multicenter Evaluation of a Sequence-Based Protocol for Subtyping Shiga Toxins and Standardizing Stx Nomenclature
Multicenter Evaluation of a Sequence-Based Protocol for Subtyping Shiga Toxins and Standardizing Stx Nomenclature
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DOI：
10.1128/jcm.00860-12
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发表时间：
2012-09-01
影响因子：
9.4
通讯作者：
O'Brien, Alison D.
中科院分区：
文献类型：
--
作者：
Scheutz, Flemming;Teel, Louise D.;O'Brien, Alison D.
当产生滋贺毒素的大肠杆菌（STEC）菌株作为人类疾病的病原体出现时，鉴定出两种类型的毒素：滋贺毒素1型（Stx 1）（几乎与由志贺菌1型产生的滋贺毒素相同）和免疫学上不同的2型（Stx 2）。随后，许多STEC菌株已被表征为表达具有氨基酸序列变化的毒素，其中一些赋予独特的生物学特性。这些变异体被归类为Stx 1或Stx 2型，通常命名为表明它们在序列或表型上与主要的Stx 1或Stx 2型不同。毒素命名缺乏特异性或一致性，导致STEC菌株的表征非常混乱。由于感染的严重后果归因于某些Stx亚型，而其他Stx亚型则较少，因此我们试图更好地定义主要Stx 1和Stx 2类型中的毒素亚型。我们比较了285个Stx 1和Stx 2有效序列变异的相关性水平，并确定了三种Stx/Stx 1和七种Stx 2亚型的共同序列特征。开发了一种新的、简单的PCR亚型分型方法，对48种原型STEC菌株进行了独立测试，并在6个临床和研究中心进行了改进，以测试PCR的重现性、灵敏度和特异性。使用一致的模式命名的Stx毒素和stx基因的系统发育序列为基础的相关性的全毒素蛋白质，我们开发了一种分型方法，应避免需要生物测定每个新描述的毒素，并预测重要的生物学特性。
When Shiga toxin-producing Escherichia coli (STEC) strains emerged as agents of human disease, two types of toxin were identified: Shiga toxin type 1 (Stx1) (almost identical to Shiga toxin produced by Shigella dysenteriae type 1) and the immunologically distinct type 2 (Stx2). Subsequently, numerous STEC strains have been characterized that express toxins with variations in amino acid sequence, some of which confer unique biological properties. These variants were grouped within the Stx1 or Stx2 type and often assigned names to indicate that they were not identical in sequence or phenotype to the main Stx1 or Stx2 type. A lack of specificity or consistency in toxin nomenclature has led to much confusion in the characterization of STEC strains. Because serious outcomes of infection have been attributed to certain Stx subtypes and less so with others, we sought to better define the toxin subtypes within the main Stx1 and Stx2 types. We compared the levels of relatedness of 285 valid sequence variants of Stx1 and Stx2 and identified common sequences characteristic of each of three Stx/Stx1 and seven Stx2 subtypes. A novel, simple PCR subtyping method was developed, independently tested on a battery of 48 prototypic STEC strains, and improved at six clinical and research centers to test the reproducibility, sensitivity, and specificity of the PCR. Using a consistent schema for nomenclature of the Stx toxins and stx genes by phylogenetic sequence-based relatedness of the holotoxin proteins, we developed a typing approach that should obviate the need to bioassay each newly described toxin and that predicts important biological characteristics.