Development and Evaluation of an Indirect ELISA for Detection of Porcine Epidemic Diarrhea Virus IgA in Pig Serum and Milk Captured by Monoclonal Antibody

For the rapid and accurate evaluation of the IgA antibody level of porcine epidemic diarrhea virus (PEDV) in pig serum and milk,a specific PEDV IgG monoclonal antibody (MAb) 8A3 was screened from four strains of PEDV MAb,which could capture all virus particles (inactivated virus cell culture medium) of PEDV efficiently.In this method,the coating concentration of 6.0 μg/mL showed the optimal performance of MAb 8A3,the cut-off value (D_{450 nm}) was settled as 0.34,it had no cross-reactivity with the positive serums of common porcine viruses.Compared with immune-peroxidase monolayer assay (IPMA),the concordance rates of established ELISA for positive and negative serum detection were 98.7% (152/154) and 98.0% (145/148),respectively.For positive and negative samples of colostrum and milk,the concordance rates of the established ELISA compared with IPMA were 100% (60/60) and 95.8% (23/24),respectively.IgA levels in colostrum and milk samples during lactation detected by established ELISA were highly correlated with trends in neutralizing titers (kappa=0.835).Collectively,the indirect ELISA in this study had high sensitivity and specificity,it was a rapid and objective method suitable for large-scale detection of PEDV IgA in clinical samples.