Submitted to: Biosecurity and Bioterrorism
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/15/2013
Publication Date: 12/9/2013
Citation: Hodge, D.R., Prentice, K.W., Ramage, J.G., Prezioso, S., Gauthier, C., Swanson, T., Hastings, R., Basavanna, U., Datta, S., Sharma, S.K., Garber, E.A., Staab, A., Pettit, D., Drumgoole, R., Swaney, E., Estacio, P.I., Elder, I.A., Kovacs, G., Morse, B.S., Kellogg, R.B., Stanker, L.H., Morse, S.A., Pillai, S.P. 2013. Comprehensive laboratory evaluation of a highly specific lateral flow assay for the presumptive identification of ricin in suspicious white powders and environmental samples. Biosecurity and Bioterrorism. 4:237-250. DOI: 10.1089/bsp.2013.0053. Interpretive Summary: Ricin is a highly toxic plant toxin derived from the common castor plant. Because of the wide availability of the seeds and source plants, as well as the ease of production, stability, and lethal potency, ricin is considered to be a bioterrorism threat and is the most common biological agent used in biocrimes. It is classified by the Centers for Disease Control and Prevention as a Category-B agent for public healthy preparedness efforts. The purpose of this study was to conduct a multi-center evaluation of the sensitivity, specificity, reproducibility, and limitations of a Lateral Flow Assay(a simple dip-stick)for ricin. The primary outcome of this evaluation demonstrates the utility of such an assay allowing for appropriate and effective decisions by first responders and public health professionals.
Technical Abstract: Ricin, a heterodimeric toxin that is present in the seeds of the Ricinus communis plant, is the most frequently encountered biothreat agent by law enforcement agencies in the United States. Even in untrained hands, the easily obtainable seeds can yield a highly toxic product that has been used in various types of threats, including so-called “white-powder” letters. Although the vast majority of these threats are hoaxes, an impediment to accurate hazard assessments by first responders is the unreliability of rapid detection assays for ricin, such as Lateral Flow Assays(LFAs). One of the complicating factors associated with LFAs is the incorporation of antibodies of poor specificity that cross-react with near-neighbors or with plant lectins that are capable of non-specifically cross-linking the capture and detector antibodies. Because of the compelling and critical need to promote the interests of public safety and public health, the Department of Homeland Security conducted a comprehensive laboratory evaluation and validation study of a commercial LFA for the rapid detection of ricin. This study was conducted using comprehensive inclusivity and exclusivity panels of ricin and near-neighbor plant materials, along with panels of lectins and “white-powders,” to determine the specificity, sensitivity, limits-of-detection, dynamic range, and repeatability of the assay for the specific intended use of evaluating suspicious white powders and environmental samples.