Expression of porcine-derived IgA against PEDV and use of Alg-CS gel to protect the IgA from degradation in simulated gastric fluid.

Porcine epidemic diarrhea virus (PEDV) is a major pathogen that causes severe diarrhea and high mortality in piglets. Immunoglobulin A (IgA) in milk provides more-effective protection for newborn piglets than immunoglobulin G (IgG). In this study, the heavy- and light-chain genes of IgA were cloned from peripheral blood mononuclear cells (PBMCs) and colostrum of pigs immunized with PEDV. Subsequently, the IgA was expressed in Chinese hamster ovary (CHO) cells and purified via affinity chromatography. Three IgA antibodies were obtained (5HV1, 1HV2, and 11HV2), and all three exhibited neutralizing activity against PEDV. The half-maximal effective inhibitory concentrations (IC50) of 5HV1, 1HV2, and 11HV2 against PEDV were determined to be 0.7906 µg/mL, 4.113 µg/mL, and 1.026 µg/mL, respectively. A Western blot assay demonstrated that the IgA antibodies exhibited specific binding affinity for the S1 protein (aa 1-506) and the S1A protein (aa 1-239) of PEDV. While these IgA antibodies were susceptible to degradation in gastric fluid, Alg-CS gel effectively shielded them from degradation and preserved their immunoreactivity with the S protein in simulated gastric fluid. The results of this study provide useful information for the application of IgA against PEDV infections.