Rapid Diagnostic Test for Phospholipase A2 Detection in Coral Snake Envenomation

Background: Snakebite envenomation is a common and potentially life-threatening emergency in dogs, particularly in regions where elapid and viperid snakes are endemic. Secreted phospholipase A2 is a major toxic component of snake venom responsible for myotoxicity, neurotoxicity, hemolysis, and coagulopathy. Currently, no point-of-care tool exists to objectively quantify circulating venom burden at presentation, so clinicians rely on subjective assessment of clinical signs to guide antivenom dosing, often resulting in under- or over-treatment. Methods: We developed and analytically validated a lateral flow immunoassay strip for rapid, quantitative detection of serum snake venom (sv)PLA2 following envenomation by Micrurus fulvius (eastern coral snake). The assay employs a sandwich immunodetection strategy in which svPLA2 is captured between a FITC-labeled and a biotinylated anti-PLA2 polyclonal antibody, forming a gold nanoparticle-labeled complex that produces a visible test line at a streptavidin capture zone and a control line at an anti-FITC line. A standard curve was generated from serial dilutions of svPLA2 and fit to a log-linear regression model. The assay was then applied to serum samples from eight clinical canine patients. Results: The standard curve followed the equation y = 277,524·ln(x) − 571,808 (R² = 0.973), yielding a limit of detection of approximately 2.4 µg/mL and a limit of quantification of approximately 14.3 µg/mL. Among the eight patient samples, three showed no detectable svPLA2 (true negatives), while five showed clearly elevated signal consistent with envenomation, with intensity varying widely across positive samples, reflecting known variability in venom yield. One sample fell between the LOD and LOQ and was interpreted qualitatively as positive without quantitative estimation. Conclusions: This lateral flow strip assay reliably and rapidly distinguishes envenomated from non-envenomated dogs and stratifies relative svPLA2 burden. This platform offers a practical, equipment-light diagnostic tool to guide antivenom dosing decisions and may serve as a companion diagnostic for emerging PLA2-targeted therapies.