Comprehensive Laboratory Evaluation of a Specific Lateral Flow Assay for the Presumptive Identification of Abrin in Suspicious White Powders and Environmental Samples

Abstract

Abrin is a heterodimeric toxin present in the seeds of the Abrus precatorius plant. The easily obtainable seeds can yield a highly toxic product that can be used in various types of biocrimes and terrorism-related activities, including "white-powder" letters. Although the vast majority of these threats are hoaxes, the lack of rapid and reliable detection assays for abrin, such as lateral flow assays (LFAs), can be an impediment to accurate and rapid hazard assessment. One of the complicating factors associated with LFAs is the use of antibodies of poor affinity and specificity that cross-react with near neighbors or that bind to plant lectins, which are capable of nonspecifically cross-linking the capture and detector antibodies. Because of the critical need to promote public safety and public health, we conducted a comprehensive laboratory evaluation of a commercial LFA for the rapid detection of abrin. This study was conducted using comprehensive inclusivity and exclusivity panels of abrin and near-neighbor plant materials, along with panels of lectins, related proteins, white powders, and environmental background material, to determine the sensitivity, specificity, limit of detection, dynamic range, and repeatability of the assay for the specific intended use of evaluating suspicious white powders and environmental samples for the presumptive presence of abrin.

Comprehensive Laboratory Evaluation of a Specific Lateral Flow Assay for the Presumptive Identification of Francisella tularensis in Suspicious White Powders and Aerosol Samples

“…They were able to detect F. tularensis in both lemming carcasses and the well water in which the carcasses were found; however, this assay was less sensitive than PCR. Rapid BTA assays have previously been evaluated for the detection of biothreat agents including orthopoxviruses, 36 ricin, 37 abrin, 38 Bacillus anthracis, 32,39 and Yersinia pestis. 40 Limited evaluations have also been conducted with assays for the detection of Yersinia pestis, 41 botulinum neurotoxins, 42,43 and staphylococcal enterotoxins.…”

Comprehensive Laboratory Evaluation of a Highly Specific Lateral Flow Assay for the Presumptive Identification ofBacillus anthracisSpores in Suspicious White Powders and Environmental Samples

“…48 Simple to use and requiring minimal training, 49 LFAs are ideal for use by first responders and law enforcement officers to test suspicious materials in field settings. BioThreat Alert Ò Assays have previously been evaluated for the detection of other biothreat agents, including orthopoxviruses, 50 ricin, 33 abrin, 34 and Yersinia pestis. 51 Limited evaluations have also been conducted with LFAs for the detection of Francisella tularensis (unpublished data), botulinum neurotoxins, 52 and staphylococcal enterotoxins.…”

The analysis of abrin in food and beverages

“…The analysis of food is frequently complicated by the presence of interferents or matrix effects. Direct testing of the abrin protein has been performed by ELISAs [58][59][60][61], immunochromatographic strips [62][63][64][65], multiplex detection immunoassay [66] and ECL assays [53,60]. Indirect means of testing for abrin include using real-time PCR to test for the genes encoding the protein [67] and determining the small molecule abrine by HPLC-MS/MS [68,69].…”

“…Lateral flow devices (LFDs) for abrin testing are commercially available [64,65]. Visual identification of a positive response in an LFD depends upon the ability of the analyst; however, portable instrumental readers can be used.…”

“…Visual identification of a positive response in an LFD depends upon the ability of the analyst; however, portable instrumental readers can be used. In a multi-laboratory study to evaluate the use of commercially-available LFD devices for determining abrin in white powders and environmental samples, the following foods were analyzed: milk, coffee creamer, sugar, baking powder, baking soda, corn starch, popcorn salt, rice flour, wheat flour, soy flour, infant formula (iron supplemented and low iron varieties) and brewer's yeast [65]. The samples were diluted in buffer prior to being tested at a sample concentration of 10 mg/mL.…”