L. monocytogenes expresses several virulence proteins [15], including Internalin A (InlA), which promotes bacterial adhesion and invasion of the host cell [15]. InlA possesses N-terminal AZD8931 chemical structure leucine-rich repeats that facilitate anchoring to the bacterial cell wall, while the most distal extracellular

domain binds to E-cadherin, which is crucial for host cell–cell adhesion and maintenance of tissue architecture. Both pathogenic and non-pathogenic Listeria species can be found in the same environment or food [16]. However, when an enrichment step is used, the non-pathogenic species may overgrow and outcompete L. monocytogenes[17–19], leading to false-negative AZD2171 supplier results. L. innocua is the most frequently found bacteria in Listeria-contaminated foods [17, 20], thus presenting a challenge for the specific capture and detection of pathogenic Listeria[21]. Hence, it is essential to develop methods that are capable of detecting pathogenic species in the presence of non-pathogenic species. Immunological approaches to detect pathogens in food are attractive; however, assay performance depends

on the quality and specificity of the antibodies used [14, 22]. For detection of Listeria, two types of assay specificities are desired: Listeria genus- or L. monocytogenes-specific tests. Anti-Listeria antibodies available from research laboratories or commercial vendors are associated with problems of low affinity [23], reaction to heterologous antigens [24, 25], lack of reaction towards all serotypes of L.

monocytogenes[23, 26–28], lack of reaction due to physiological stress induced by growth media or assay parameters [29, 30], LY3023414 clinical trial and lack of compatibility with certain bioassay platforms [14, 22, 31]. Thus, there is a need for continued efforts to produce high-quality antibodies. The recovery of low numbers of pathogens from complex food matrices also impedes their rapid and sensitive detection [31, 32]. Antibodies are routinely used as affinity ligands to separate and concentrate the target analyte from sample matrices using paramagnetic beads (PMBs) [31–34] and also as recognition or reporter molecules on immunoassay platforms [31, 35, 36]. The PMB-captured cells may be presumptively identified by plating them on selective or differential media [37], or their identity may be confirmed O-methylated flavonoid by PCR [38, 39], flow cytometry [40], or cytotoxicity assay [41]. The use of a biosensor to detect cells captured by immunomagnetic separation (IMS) is an attractive approach due to increased speed, accuracy, and detection of a low number of targets [34, 42, 43]. Fiber-optic sensors utilize laser excitation to generate an evanescent wave in order to quantify biomolecules immobilized on an optical waveguide [31, 44, 45]. A capture antibody is immobilized on the waveguide and a fluorescent (Cyanine 5 or Alexa Fluor 647)-labeled second antibody is used as a reporter for the target analyte.