title: The development of rapid fluorescence-based immunoassays, using quantum dot-labelled antibodies for the detection of Listeria monocytogenes cell surface proteins.
abstract: Listeria monocytogenes is an important food-borne pathogen with an extremely high mortality rate (approximately 30%). Therefore, a highly sensitive, reproducible and rapid assay for its detection is vital. L. monocytogenes cells employ two surface bound proteins, Internalin A (InlA) and Internalin B (InlB) to promote invasion into host cells. Recombinant forms of both proteins were previously cloned and expressed in Escherichia coli. In this paper we describe how the InlB protein was sub-divided into three shorter overlapping peptide fragments yielding truncated functional protein of M(R) 23, 35 and 45 kDa, respectively. Purification of the InlB fragments by immobilised metal affinity chromatography (IMAC) was optimised and confirmed by electrophoresis and Western blotting. Identification of the antibody binding regions was achieved by probing the expressed polypeptide domains with a panel of antibodies and antibody fragments. The cloned peptide fragments were also used to develop novel fluorescence-based immunoassays incorporating quantum dots. The application of quantum dot-labelled anti-InlA monoclonal antibodies for immunostaining L. monocytogenes was also demonstrated.
authors.affiliation: School of Biotechnology & National Centre for Sensor Research, Dublin City University, Glasnevin, Dublin 9, Ireland. Elizabeth.tully2@mail.dcu.ie
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Tully
authors.forename: Stephen
authors.initials: S
authors.lastname: Hearty
authors.forename: Paul
authors.initials: P
authors.lastname: Leonard
authors.forename: Richard
authors.initials: R
authors.lastname: O'Kennedy
mesh_terms: D000907:Antibodies, Bacterial / Q000276:immunology; D000911:Antibodies, Monoclonal / Q000276:immunology; D001426:Bacterial Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D004926:Escherichia coli / Q000737:chemistry / Q000235:genetics; D007118:Immunoassay / Q000379:methods; D008089:Listeria monocytogenes / Q000235:genetics / Q000276:immunology; D008565:Membrane Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification*; D045663:Quantum Dots; D011994:Recombinant Proteins / Q000235:genetics / Q000276:immunology / Q000302:isolation & purification
chemical_list: D000907:Antibodies, Bacterial; D000911:Antibodies, Monoclonal; D001426:Bacterial Proteins; D008565:Membrane Proteins; D011994:Recombinant Proteins; C095768:inlB protein, Listeria monocytogenes; C069761:internalin protein, Bacteria