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Journal of Nucleic Acids
Volume 2014 (2014), Article ID 214929, 8 pages
Research Article

Selective Evolution of Ligands by Exponential Enrichment to Identify RNA Aptamers against Shiga Toxins

1Department of Infectious Disease and Global Health, Tufts Cummings School of Veterinary Medicine, Tufts University, 200 Westboro Road, Building 20, North Grafton, MA 01536, USA
2AstraZeneca, 35 Gatehouse Drive, Waltham, MA 02451, USA

Received 19 December 2013; Revised 6 March 2014; Accepted 25 March 2014; Published 15 April 2014

Academic Editor: Birte Vester

Copyright © 2014 Sreerupa Challa et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Infection with Shiga toxin- (Stx-) producing E. coli causes life threatening hemolytic uremic syndrome (HUS), a leading cause of acute renal failure in children. Of the two antigenically distinct toxins, Stx1 and Stx2, Stx2 is more firmly linked with the development of HUS. In the present study, selective evolution of ligands by exponential enrichment (SELEX) was used in an attempt to identify RNA aptamers against Stx1 and Stx2. After 5 rounds of selection, significant enrichment of aptamer pool was obtained against Stx2, but not against Stx1, using a RNA aptamer library containing 56 random nucleotides (N56). Characterization of individual aptamer sequences revealed that six unique RNA aptamers (mA/pC, mB/pA, mC, mD, pB, and pD) recognized Stx2 in a filter binding assay. None of these aptamers bound Stx1. Aptamers mA/pC, mB/pA, mC, and mD, but not pB and pD, partially blocked binding of Alexa 488-labeled Stx2 with HeLa cells in a flow cytometry assay. However, none of the aptamers neutralized Stx2-mediated cytotoxicity and death of HeLa cells.