Development of an automated chemiluminescence immunoassay for detection of IgA antibodies against porcine epidemic diarrhea virus spike

Porcine epidemic diarrhoea virus (PEDV) causes substantial financial losses on pig farming worldwide. Monitoring PEDV-specific IgA antibodies is essential for assessing vaccine efficacy. In this study, we developed a fully automated chemiluminescence immunoassay (CLIA) for the detection of PEDV IgA antibodies in both serum and milk. This S1-CLIA utilizes recombinant S1 protein-coated magnetic particles (S1-MPs) for antibody capture and an acridinium ester-labeled mouse anti-pig IgA monoclonal antibody (mpIgA-AE) to generate chemiluminescence signals. Under optimized conditions, S1-CLIA achieved a diagnostic sensitivity of 96.30% and specificity of 98.48%, with a cut-off index of 1.0. S1-CLIA exhibited excellent repeatability (coefficient of variation < 10%) and no cross-reactivity with sera positive for other common swine pathogens. Compared to a commercial enzyme-linked immunosorbent assay (ELISA), S1-CLIA achieved 93.93% agreement rate, but offered a significantly broader dynamic range (35.48-fold). Notably, S1-CLIA results correlated well with virus neutralization titers (VNT), yielding R² values of 0.6660 (serum) and 0.7639 (milk). With capability of fully automated testing, this novel S1-CLIA presents a robust platform for large-scale evaluation of PEDV immunity.