García-Aljaro Cristina, Muniesa Maite, Jofre Juan, Blanch Anicet R
Departament de Microbiologia, Universitat de Barcelona, Barcelona, Spain.
FEMS Microbiol Lett. 2006 May;258(1):127-35. doi: 10.1111/j.1574-6968.2006.00213.x.
Shiga toxin-converting bacteriophages are the main vehicle involved in horizontal transmission of stx1 and stx2 genes, which has led to the current spread of stx genes among a high number of Escherichia coli serotypes and other enterobacteria. Several stx gene variants have been described, although some of the variants have never been isolated from inducible bacteriophages. In this study, two stx2g-carrying bacteriophages induced from two different E. coli O2:H25 strains isolated from different wastewater samples were characterized. These bacteriophages when transduced into Shigella sonnei retained their ability to produce Stx2 protein. They had similar but not identical DNA restriction patterns, and similar host ranges. Electron microscopy studies showed that they had isometric capsids with short tails, which resembled phage 933W. However, DNA cross-hybridization studies showed that phage 933W was not closely related to stx2g bacteriophages. This first description of stx2g-carrying bacteriophages enlarges the list of stx-carrying bacteriophages involved in horizontal transmission of stx genes in the environment.
志贺毒素转换噬菌体是stx1和stx2基因水平传播的主要载体，这导致了stx基因目前在大量大肠杆菌血清型和其他肠杆菌中的传播。已经描述了几种stx基因变体，尽管其中一些变体从未从可诱导噬菌体中分离出来。在本研究中，对从不同废水样本中分离出的两种不同大肠杆菌O2:H25菌株诱导出的两种携带stx2g的噬菌体进行了表征。这些噬菌体转导到宋内志贺菌中后仍保留产生Stx2蛋白的能力。它们具有相似但不完全相同的DNA限制性图谱和相似的宿主范围。电子显微镜研究表明，它们具有短尾的等轴衣壳，类似于噬菌体933W。然而，DNA交叉杂交研究表明，噬菌体933W与stx2g噬菌体没有密切关系。对携带stx2g的噬菌体的首次描述扩大了参与stx基因在环境中水平传播的携带stx的噬菌体名单。
