Rapid Analysis of Pacific Ciguatoxins in Fish Extracts with a Lateral Flow Assay

The increasing spread of toxin-producing Gambierdiscus dinoflagellates has led to cases of ciguatera poisoning in previously nonendemic regions. Ciguatoxins (CTXs) are potent, heat-stable compounds responsible for ciguatera, and their rapid and reliable analysis in seafood is essential to prevent illness. This study presents the development of the first lateral flow assay (LFA) for the detection of major Pacific CTXs congeners. The assay employs previously developed monoclonal antibodies in a sandwich format: specific antibodies against CTX1B and CTX3C are immobilized on a single test line, while the reporter antibody is a single antibody recognizing major Pacific CTX congeners that is conjugated to gold nanoparticles. The LFA provides one-step visual results in 30 min, making it suitable for resource-limited settings. It exhibits a visual limit of detection of 400 pg/mL and the assay is highly specific, showing no cross-reactivity with other marine toxins. It successfully detected Pacific CTXs spiked in noncontaminated fish extracts, as well as in naturally contaminated samples as previously confirmed by LC-MS/MS, with an estimated cutoff of approximately 0.1 μg/kg. Overall, this LFA demonstrates great potential as a rapid screening tool for outbreak investigations and research programs.