Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 2/12/2004
Publication Date: 5/25/2004
Citation: Brewster, J.D., Paoli, G. 2004. Selective isolation of listeria monocytogenes from foods using a single-chain antibody fragment derived by phage display. Meeting Abstract. Granada, Spain. Paper #4.
Technical Abstract: Listeriosis is an often fatal foodborne illness caused by the gram positive organism Listeria monocytogenes. Rapid methods for the detection of L. monocytogenes are needed to help prevent distribution and consumption of contaminated foods. The development of methods for isolation and detection of this organism has been slowed by the lack of antibodies which specifically detect L. monocytogenes in the presence of other benign Listeria species. We recently isolated a single chain antibody fragment (scFv) using phage display technology that reacts with most known strains of L. monocytogenes, and does not cross-react with any of the other five species of Listeria. We report here experiments in which phage expressing this monoclonal scFv fragment were immobilized on support materials such as magnetic latex beads and solid glass beads and used to isolate L. monocytogenes from buffer and food extracts. Typical recovery with immunomagnetic beads was 15% (one hour incubation) in the presence of 100 fold excess of L. innocua, with no detectable recovery of the competing organism. Immunoaffinity columns provided lower recovery, but excellent specificity and larger sample capacity. Improved detection by PCR was observed for the isolated organisms due to removal of inhibitory substances. Full details of the optimization and performance (recovery, specificity, time) of the isolation procedures will be described.