Detection of antibodies against porcine epidemic diarrhea virus in serum and colostrum by indirect ELISA

An indirect porcine epidemic diarrhea virus (PEDV) anti-immunoglobulin (Ig) G ELISA based on the S1 portion of the spike protein was validated and compared with an indirect immunofluorescence assay. In serum samples from experimentally infected pigs (n = 35), anti-IgG PEDV antibodies were detected as early as 7 days post-infection. In field serum samples (n = 239), the diagnostic sensitivity of the S1 ELISA was 100% and the diagnostic specificity was 94%. The S1 ELISA showed no cross-reactivity with antibodies against other porcine coronaviruses. Colostrum samples (n = 133) were also tested for anti-PEDV IgG and IgA. The diagnostic sensitivity was 92% for IgG and 100% for IgA, and the diagnostic specificity was 90% for IgG and 99.4% for IgA. These data suggest that the S1 ELISA is a sensitive and specific test that could also be used to evaluate PEDV colostral immunity.