Porcine epidemic diarrhea virus (PEDV) is an intestinal coronavirus that can cause porcine epidemic diarrhea, leading to diarrhea, vomiting, weight loss, and even death in piglets. Due to the diversity of PEDV strains, traditional vaccines are difficult to sustainably and effectively prevent and control PEDV. This article reviews the strategies and mechanisms of active substances in regulating intracellular signaling pathways, viral proteins, and microbial metabolites to enhance the host immune function against PEDV. It emphasizes the prevention of PEDV resistance and the potential harm of PEDV breaking through interspecies barriers to the human society, aiming to provide reliable theoretical support for the development of new antiviral drugs or vaccines.
Porcine epidemic diarrhea virus/immunology* ; Animals ; Swine ; Swine Diseases/prevention & control* ; Antiviral Agents/pharmacology* ; Coronavirus Infections/virology* ; Viral Vaccines/immunology* ; Humans ; Signal Transduction

Porcine epidemic diarrhea virus (PEDV) is a highly infectious pathogen that can cause severe diseases in pigs and result in enormous economic losses in the worldwide swine industry. Previous studies revealed that PEDV exhibits an obvious capacity for modulating interferon (IFN) signaling or expression. The newly discovered type III IFN, which plays a crucial role in antiviral immunity, has strong antiviral activity against PEDV proliferation in IPEC-J2 cells. In this study, we aimed to investigate the effect of PEDV nucleocapsid (N) protein on type III IFN-λ. We found that the N proteins of ten PEDV strains isolated between 2013 and 2017 from different local farms shared high nucleotide identities, while the N protein of the CV777 vaccine strain formed a monophyletic branch in the phylogenetic tree. The N protein of the epidemic strain could antagonize type III IFN, but not type I or type II IFN expression induced by polyinosinic-polycytidylic acid (poly(I:C)) in IPEC-J2 cells. Subsequently, we demonstrated that the inhibition of poly(I:C)-induced IFN-λ3 production by PEDV N protein was dependent on the blocking of nuclear factor-κB (NF-κB) nuclear translocation. These findings might help increase understanding of the pathogenesis of PEDV and its mechanisms for evading the host immune response.
Active Transport, Cell Nucleus ; Animals ; Coronavirus Infections ; immunology ; veterinary ; virology ; Genes, Viral ; Host-Pathogen Interactions ; immunology ; Interferons ; antagonists & inhibitors ; biosynthesis ; genetics ; Interleukins ; antagonists & inhibitors ; biosynthesis ; genetics ; NF-kappa B ; metabolism ; Nucleocapsid Proteins ; genetics ; immunology ; physiology ; Porcine epidemic diarrhea virus ; genetics ; pathogenicity ; physiology ; Promoter Regions, Genetic ; Swine ; Swine Diseases ; immunology ; virology

To evaluate the immune responses of recombinant Lactobacillus casei 393 expressing Porcine Epidemic Diarrhea Viral (PEDV) N protein as oral vaccine, n gene of PEDV was subcloned into the expression vector pPG-1, and then transformed into L. casei 393 by electroporation, resulting in recombinant strain pPG-1-n/L, casei 393. The recombinant strains were induced to express interest protein, which was detected by Western blotting, immunofluorescence microscopy and the whole bacteria ELISA. And then BALB/C mice were used as an animal model immunized with recombinant strains by oral administration, and the immune efficacy was analyzed. The recombinant PEDV N protein showed the antigenic specificity, and was located on the bacterial cell walls of pPG-1-n transformed L. casei. The results of ELISA showed that the mice immunized with recombinant strains could produce remarkable special sIgA level in the feces, and high level of anti-PEDV N protein IgG in the serum (P < 0.01), but the induced antibodies in serum did not demonstrated neutralizing effect. Statistical significant difference was observed among the spleen lymphocyte proliferation index (LPI) among the immunization groups of mice and control groups. And there was significant increase. of IFN-gamma and IL-4 contents in the supernatant of spleen cell culture in immunized group. In conclusion, the oral immunizations with recombinant L. casei 393 can induce significant specific mucosal PEDV N-specific IgA response as well as serum IgG responses, and can evoke both mucosal immune and system immune responses.
Administration, Oral ; Animals ; Antibody Formation ; Coronavirus Infections ; prevention & control ; Female ; Immunity, Mucosal ; immunology ; Lactobacillus casei ; genetics ; metabolism ; Mice ; Mice, Inbred BALB C ; Nucleocapsid Proteins ; biosynthesis ; genetics ; immunology ; Porcine epidemic diarrhea virus ; immunology ; Recombinant Proteins ; biosynthesis ; genetics ; immunology ; Swine ; Viral Vaccines ; administration & dosage ; immunology