Selection and Characterization of Aptamers against Salmonella typhimurium Using Whole-Bacterium Systemic
Evolution of Ligands by Exponential Enrichment (SELEX)
- Publication date
- Publisher
Abstract
In
this paper, a high-affinity ssDNA aptamer binding to Salmonella typhimurium was obtained by a whole-bacterium-based
Systemic Evolution of Ligands by Exponential Enrichment (SELEX) procedure.
After nine rounds of selection with <i>S. typhimurium</i> as the target, a highly enriched oligonucleotide pool was sequenced
and then grouped into different families based on primary sequence
homology and secondary structure similarity. Eleven sequences from
different families were selected for further characterization via
flow cytometry analysis. The results showed that the sequence ST2P
demonstrates affinity for <i>S. typhimurium</i> much more
strongly and specifically than other sequences tested. The estimated <i>K</i><sub>d</sub> value of this particularly promising aptamer
was 6.33 ± 0.58 nM. To demonstrate the potential use of the aptamers
in the quantitative determination of <i>S. typhimurium</i>, a fluorescent bioassay with the aptamer ST2P was prepared. Under
optimal conditions, the correlation between the concentration of <i>S. typhimurium</i> and fluorescent signal was found to be linear
within the range of 50–10<sup>6</sup> cfu/mL (<i>R</i><sup>2</sup> = 0.9957). The limit of detection (LOD) of the developed
method was found to be 25 cfu/mL. This work demonstrates that this
aptamer could potentially be used to improve the detection of <i>S. typhimurium</i>