Evaluation of the Ability of Anti-Lipopolysaccharide Aptamers to Discriminate Various Pathogenic E. coli Bacteria
Evaluation of the Ability of Anti-Lipopolysaccharide Aptamers to Discriminate Various Pathogenic E. coli Bacteria
John G. Bruno
ABSTRACT
Lengthy 200 base DNA aptamers were developed against extracted lipopolysaccharides (LPS) of E. coli O157 and the so called “Big six” non-O157 Shiga-toxin producing E. coli (STEC) serovars (O26, O45, O103, O111, O121 and O145). These aptamers were assessed by enzyme-linked aptamer sorbent assay (ELASA) to rank their relative affinities and discriminatory ability for distinguishing between each of the STEC serovars. The most specific biotinylated aptamers from the ELASA screening were then attached to streptavidin-coated magnetic beads (SAv-MBs) and used to capture their cognate and related E. coli serovars. Capture was assessed by fluorescence microplate assessment following acridine orange staining. While there was significant cross-reactivity between the various captured serotypes, each of the anti-LPS aptamer candidates showed a preference for its cognate E. coli serotype. Results suggest that these aptamers may be useful for enriching specific E. coli pathogens during aptamer-magnetic separation in food samples, leading to a greater ability to detect these serotypes if coupled with genetic identification techniques such as PCR or gene probe hybridization.
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