Validation of a Lateral Flow Assay for the Qualitative Detection of Domoic Acid in Shellfish

BACKGROUND: Domoic acid (DA), produced by Pseudo-nitzschia species during harmful algal blooms, causes Amnesic Shellfish Poisoning (ASP) in humans. Regulatory monitoring relies on accurate but resource-intensive liquid chromatography with ultraviolet detection (LC-UV) reference method. There is urgent need for validated rapid screening tools for field and laboratory settings. OBJECTIVE: This study evaluated the Sensoreal ASP Alert™ lateral flow assay (LFA) for qualitative detection of DA in bivalves through single-laboratory validation, combining AOAC and Interstate Shellfish Sanitation Conference (ISSC) guidelines. METHODS: The LFA was assessed for Probability of Detection (sensitivity, specificity, false positives, false negatives), ruggedness, and comparability against LC-UV reference. Validation used spiked (mussels and scallops) and 168 naturally contaminated samples representing diverse species and origins. Additional assessments included selectivity against other marine biotoxins and semi-quantitative interpretation via SensoRead™ scanner. RESULTS: At a 15 mg/kg decision threshold (75% of the regulatory maximum permitted limit, MPL), the LFA achieved high sensitivity (0.983) and specificity (0.817) in spiked samples, with 0.90 overall agreement (κ = 0.80). Naturally contaminated samples showed near-perfect LC-UV agreement (sensitivity 0.983; specificity 0.827; κ = 0.869). Ruggedness testing revealed no significant performance differences under varying analysts, lots, or incubation conditions. No cross-reactivity was observed with paralytic shellfish toxins (saxitoxin, gonyautoxins GTX2&3, C toxins C1&2), okadaic acid (OA), dinophysistoxin-2 (DTX2), azaspiracids-1 and -2 (AZA1&2), microcystins (MCs) and tetrodotoxin (TTX). The scanner's Low/Medium/High classification provided early-warning capability, with substantial agreement at a secondary 7.5 mg/kg threshold (κ = 0.667). Combined spiked and naturally contaminated data (n = 288) confirmed 0.920 overall agreement (κ = 0.840). CONCLUSION: Sensoreal ASP Alert™ LFA is a robust, accurate, user-friendly rapid DA screening method. It demonstrates excellent comparability to LC-UV, high sensitivity, and rugged performance. Its semi-quantitative classification aids proactive monitoring and regulatory decision-making. HIGHLIGHTS: A lateral flow assay for ASP has been validated successfully.