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Highlights • Coated PEDV-loaded microspheres were developed by centrifugal granulation-fluidized bed coating. • Coated PEDV-loaded microspheres could protect PEDV antigens against the complex gastrointestinal environment in vitro and in vivo. • Oral vaccination with coated PEDV-loaded microspherescould induce higher levels of PEDV-specific antibodies in weaned piglets than the orally delivered PEDV only group. Abstract Porcine epidemic diarrhea virus (PEDV) infects pigs of all ages by invading villous epithelial cells of the small intestine causing severe diarrhea with high mortality rate in suckling piglets. Mucosal immunity is believed to play an important role in PEDV control and mucosal delivery of vaccines induces mucosal immunity more efficiently than parenteral vaccination. In this study, coated PEDV-loaded microspheres with the size range of 700–900 μm in diameter were developed by centrifugal granulation-fluidized bed coating and demonstrated as an effective oral delivery system to protect PEDV antigens against the complex gastrointestinal environment by detecting the live virus particles in microspheres after the simulated gastric fluid treatment and the PEDV RNA in fecal swabs collected from all weaned piglets (100%) orally inoculated with coated PEDV-loaded microspheres. Weaned piglets orally immunized with coated PEDV-loaded microspheres developed higher levels of PEDV-specific antibodies (IgG and IgA) in their sera and saliva than those negative control groups (p < 0.001 or p < 0.01). Furthermore, neutralization assays demonstrated that serum antibodies in coated PEDV-loaded microspheres groups could significantly inhibit virus infection in Vero cells, compared to PEDV only group (p < 0.05). Overall, our results indicate that the coated PEDV-loaded microspheres might serve as an effective way to induce PEDV-specific mucosal immunity in pigs against PEDV. [ABSTRACT FROM AUTHOR]

Porcine epidemic diarrhea (PED) is an important re-emergent infectious disease and inflicts huge economic losses to the swine industry worldwide. To meet the pressing need of developing a safe and cost-efficient PED maternal vaccine, we generated three PED subunit vaccine candidates, using recombined Salmonella flagellin (rSF) as a mucosal molecular adjuvant. Domain D3 in rSF was replaced with COE domain of PEDV to generate rSF-COE-3D. COE fused to the flanking C′/N′ terminal of rSF yielded rSF-COE-C and rSF-COE-N. As a result, rSF-COE-3D could significantly improve COE specific antibody production including serum IgG, serum IgA, mucosal IgA and PEDV neutralizing antibody. Furthermore, rSF-COE-3D elicited more CD3 + CD8 + T cell and cytokine production of IFN-γ and IL-4 in mouse splenocytes. In summary, our data showed that rSF-COE-3D could improve specific humoral and mucosal immunity in mice, thus suggesting that rSF-COE-3D could be applied as a novel efficient maternal PED vaccine. [ABSTRACT FROM AUTHOR]