Lateral flow immunoassay for highly sensitive antibody detection of Clostridium perfringens ε toxin

ε-toxin, secreted by Clostridium perfringens , causes severe enterotoxemia in sheep and goats, resulting in substantial economic losses in the small ruminant industry. Monitoring ε-toxin-specific antibody levels is essential for early disease surveillance, vaccine-induced immunity evaluation, and infection status assessment of unvaccinated animals. Current detection methods such as enzyme-linked immunosorbent assay are time-consuming and instrument-dependent, limiting their use in resource-limited settings. To address these limitations, we developed a gold nanoparticle (GNP)-based lateral flow immunoassay (LFIA) for the detection of ε-toxin-specific antibodies. The strip was constructed using Staphylococcal protein A-conjugated GNPs as the detection probe and purified ε-toxin antigen as the capture reagent on the test line. The assay enabled rapid detection of ε-toxin-specific antibodies with a visual limit of detection (vLOD) of 3.3 ng/mL. Quantitative analysis based on the calibration curve yielded a limit of detection (LOD) of 0.028 ng/mL (28 pg/mL). Furthermore, the results showed a strong correlation with those obtained using a commercial ELISA kit (R² = 0.93), confirming the reliability of the developed LFIA. Analysis of 84 clinical samples, including 20 samples below the LOD and 64 samples with concentrations ranging from 3.94 to 299.50 ng/mL, demonstrated the excellent practical applicability of the LFIA. The developed GNP-based LFIA represents a high-performance, rapid, and user-friendly detection platform for monitoring ε-toxin-specific antibody levels following clostridial vaccination, providing a powerful tool for epidemiological investigations of Clostridium perfringens .