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ARS Home » Pacific West Area » Albany, California » Western Regional Research Center » Foodborne Toxin Detection and Prevention Research » Research » Publications at this Location » Publication #310014
Title: Immunosorbent analysis of toxin contamination in milk and ground beef using IgY-based ELISA

Author
item Brandon, David
item Korn, Anna

Submitted to: Food and Agricultural Immunology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 11/29/2015
Publication Date: 1/5/2016
Publication URL: http://handle.nal.usda.gov/10113/5190190
Citation: Brandon, D.L., Korn, A.M. 2016. Immunosorbent analysis of toxin contamination in milk and ground beef using IgY-based ELISA. Food and Agricultural Immunology. 27:(4):496-508. doi: 10.1080/09540105.2015.1126809.

Interpretive Summary: Analytical methodology to detect ricin and Shiga toxins (Stx) in food matrices is important because of the potential use of ricin in food as a terrorist weapon, and the presence of Stx in food as a result of contamination with Shiga-toxin producing E. coli bacteria (STEC) that has lead to serious foodborne disease outbreaks. One means of detecting foodborne contaminants and adulterants in foods is the use of immunological assays based on antibodies. An unconventional type of antibody is the IgY found in chicken eggs. This study demonstrated that IgY antibodies could be used effectively to detect two toxins, ricin and Shiga toxin 2, in milk and ground beef samples. This study also demonstrated that the IgY detection antibodies were more heat-stable than mouse serum anti-toxins. Some of the properties of IgY and the genes that encode them in chicken immune cells may provide the basis for new immunosensor systems with enhanced stability and/or sensitivity.

Technical Abstract: Analytical methodology to detect ricin and Shiga toxins (Stx) in food matrices is important because of the potential use of ricin in food as a terrorist weapon, and the presence of Stx in food as a result of contamination with Shiga-toxin producing E. coli (STEC) that has lead to serious foodborne disease outbreaks. Monoclonal antibodies (mAbs) that bind each toxin were used for capture in sandwich enzyme-linked immunosorbent assay (ELISA), and IgY polyclonal antibodies were prepared for use as detection antibodies. IgY was detected using horseradish peroxidase (HRP)-conjugated anti-IgY and colorimetric or chemiluminescent substrates. The ricin assay systems detect pure ricin as well as crude ricin-containing castor extract, but do not significantly respond to isolated ricin chains, heat-denatured ricin, or the related agglutinin, Ricinus communis agglutinin 1 (RCA-1). The lower limit of detection (LOD) was 0.13 ng/mL for milk samples containing 0 - 4% fat and 0.8 ng/g in ground beef. The Stx2 assay system does not detect Stx1 or heat-denatured Stx2 and the LODs for Stx2 of 0.13 ng/mL in milk and 0.7 ng/g in ground beef. Using standard 96-well-plate formats, the assays detect less than 1 x 10-4 of an estimated lethal oral dose of either toxin in a serving of milk. This study also demonstrated that the IgY detection antibodies were more heat-stable than mouse polyclonal anti-toxins at 65° C, but not necessarily more heat-stable than individual mAbs.