title: Cy5 labeled antimicrobial peptides for enhanced detection of Escherichia coli O157:H7.
abstract: Fluorescently labeled antimicrobial peptides were evaluated as a potential replacement of labeled antibodies in a sandwich assay for the detection of Escherichia coli O157:H7. Antimicrobial peptides naturally bind to the lipopolysaccharide component of bacterial cell walls as part of their mode of action. Because of their small size relative to antibodies peptides can bind to cell surfaces with greater density, thereby increasing the optical signal and improving sensitivity. This method combines the specificity of a capture antibody with the increased sensitivity provided by using a labeled peptide as a detection molecule. The antimicrobial peptides cecropin P1, SMAP29, and PGQ were labeled with the fluorescent dye Cy5 via maleimide linker chemistry. Preliminary screening using a whole-cell solution binding assay revealed that Cy5 cecropin P1 enhanced the detection of E. coli O157:H7 relative to a Cy5 labeled anti-E. coli O157:H7 antibody 10-fold. Detection sensitivity of antibody and peptide were also compared with a prototype immuno-magnetic bead biosensor. Detection using Cy5 cecropin P1 resulted in a 10-fold improvement in sensitivity. Correlation of peptide antimicrobial activity with detection of E. coli O157:H7 indicated that activity was not predictive of the sensitivity of the fluorescent assay.
authors: Warrior Science Technology & Applied Research Directorate, Natick Soldier Research, Development & Engineering Center, Natick, MA 01760-5020, USA. steven.arcidiacono@us.army.mil
authors: Steven
authors: S
authors: Arcidiacono
authors: Philip
authors: P
authors: Pivarnik
authors: Charlene M
authors: CM
authors: Mello
authors: Andre
authors: A
authors: Senecal
mesh_terms: D023181:Antimicrobial Cationic Peptides / Q000737:chemistry*; D002232:Carbocyanines / Q000737:chemistry*; D015169:Colony Count, Microbial / Q000379:methods*; D019453:Escherichia coli O157 / Q000737:chemistry / Q000302:isolation & purification*; D013050:Spectrometry, Fluorescence / Q000379:methods*; D013194:Staining and Labeling / Q000379:methods
chemical_list: D023181:Antimicrobial Cationic Peptides; D002232:Carbocyanines; C085321:cyanine dye 5