[Highly sensitive detection technology for biological toxins applying sugar epitopes].
The Shiga toxin is a highly poisonous protein produced by enterohemorrhagic Escherichia coli O157. This bacterial toxin causes the hemolytic uremic syndrome. Another plant toxin from castor beans, ricin, is also highly toxic. The toxin was used for assassination in London. Recently, there were several cases of postal matter containing ricin. Both toxins are categorized as biological warfare agents by the Centers of Disease Control and Prevention. Conventional detection methods based on the antigen-antibody reaction, PCR and other cell-free assays have been proposed. However, those approaches have drawbacks in terms of sensitivity, analytical time, or stability of the detection reagents. Therefore, development of a facile and sensitive detection method is essential. Here we describe new detection methods applying carbohydrate epitopes as the toxin ligands, which is based on the fact that the toxins bind cell-surface oligosaccharides. Namely, the Shiga toxin has an affinity for globobiosyl (Gb(2)) disaccharide, and ricin binds the beta-D-galactose residue. For Shiga toxin detection, surface plasmon resonance (SPR) was applied. A polyanionic Gb(2)-glycopolymer was designed for this purpose, and it was used for the assembly of Gb(2)-chips using alternating layer-by-layer technology. The method allowed us to detect the toxin at a low concentration of LD(50). A synthetic carbohydrate ligand for ricin was designed and immobilized on the chips. SPR analysis with the chips allows us to detect ricin in a highly sensitive and facile manner (10 pg/ml, 5 min). Our present approaches provide a highly effective way to counter bioterrorism.
Uzawa
Hirotaka
H
Research Center of Advanced Bionics, National Institute of Advanced Industrial Science and Technology (AIST), 1-1-1 Higashi, Tsukuba 305-8565, Japan. h.uzawa@aist.go.jp
D002241:Carbohydrates; D004187:Disaccharides / Q000138:chemical synthesis; D000939:Epitopes; D008024:Ligands; D009844:Oligosaccharides; D012276:Ricin / Q000032:analysis*; D012680:Sensitivity and Specificity; D022621:Shiga Toxin / Q000032:analysis*; D020349:Surface Plasmon Resonance / Q000379:methods*
D002241:Carbohydrates; D004187:Disaccharides; D000939:Epitopes; D008024:Ligands; D009844:Oligosaccharides; C539793:globobiosyl (Gb2) disaccharide; D022621:Shiga Toxin; D012276:Ricin