Location: Produce Safety and Microbiology ResearchTitle: Detection of bacterial toxins by lateral flow immunoassay
Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 6/24/2013
Publication Date: 7/1/2013
Citation: Ching, K.H., Stanker, L.H., He, X., Hnasko, R.M. 2013. Detection of bacterial toxins by lateral flow immunoassay. p. 1-28. Irvine, CA; Biodot.
Interpretive Summary: Early detection of pathogenic bacteria by food manufacturers throughout production can prevent large scale outbreaks of illness and subsequent product recalls. Sensitive immunoassays employing pathogen-specific monoclonal antibodies (mAbs) can augment current testing protocols, resulting in increased quality control and improved food safety. Here we describe the development of highly sensitive lateral flow immunoassays (LFIAs) for the rapid detection of bacterial toxins from Clostridium botulinum, Shiga toxigenic E. coli (STEC) and Staphylococcus aureus, and Listeria monocytogenes, all frequent foodborne contaminants. We show how these inexpensive, easy to use, disposable lateral flow devices can be used throughout food production to improve food safety and security.
Technical Abstract: Foodborne bacteria sicken over 48 million Americans each year, causing more than 200,000 hospitalizations and over 3,000 deaths. The majority of food producers operate with strict sanitation and hygiene controls throughout production to minimize the risk of product contamination. Additional consumer safeguards include sensitive testing procedures for the detection of pathogenic bacterial contamination of food products prior to distribution. Our laboratories have focused on the detection of disease causing toxins produced by pathogenic bacteria that afflict animals by the consumption of contaminated foods. Toward this aim we generated monoclonal antibodies (mAbs) against bacterial toxins and use them to develop sensitive immunoassays that can be used for their detection. Here we discuss mAbs developed in our laboratories against secreted bacterial toxins that includes botulinum neurotoxin A and B (BoNT/A, /B; Clostridium botulinum), shiga-like toxins (Stx; Shiga-toxigenic E. coli - STEC), Staphylococcal enterotoxin B (SEB; Staphylococcus aureus) and listeriolysin O (LLO; Listeria monocytogenes). In this report we discuss the use of these mAbs for toxin detection using small portable rapid lateral flow devices (LFDs) that provide a simple disposable visual indication of toxin contamination from food substrates. We describe the development of a BoNT LFD that can detect and discriminate between BoNT/A and /B serotypes with a limit of detection (LOD) < 0.2 ng/mL and 5 ng/mL respectively. In addition, we describe the development of a Stx LFD that can detect all the major shiga toxin serotypes and subtypes produced by STEC with a LOD <0.1 ng/mL for Stx2a. Moreover, we demonstrate the utility of these LFDs to effectively detect toxin from various solid and liquid food matrices. We also describe preliminary work in the generation and characterization of mAbs to SEB and demonstrate the utility of a mAb pair to detect purified SEB to <5 ng/mL using a LFD. Finally we describe the generation of monoclonal antibodies against the pore-forming LLO toxin and characterize their application in several immunoassay formats. The detection of any of these toxins would indicate contamination of a sample by pathogenic bacteria capable of causing disease. Importantly, the lateral flow immunoassay format represents an inexpensive method that can be used by minimally trained end-users for the repeated monitoring of foodborne contamination throughout food production. These LFDs provide a rapid evaluation of food products that can augment current testing methods resulting in improve food safety and security from the field to the plate.