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

To screen and identify the key host proteins interacting with the non-structural protein 15 (Nsp15) of porcine epidemic diarrhea virus (PEDV). The IP/pull-down assay and mass spectrometry were employed to screen and identify the host proteins interacting with Nsp15. The interaction between the host protein and Nsp15 was studied by co-immunoprecipitation and laser scanning confocal microscopy. Finally, Western blotting and RT-qPCR were employed to examine the interaction between SLC25a3 and PEDV. The recombinant eukaryotic expression vector pcDNA3.1(+)-Flag-Nsp15 was successfully constructed, and the host protein SLC25a3 interacting with PEDV Nsp15 was screened out. An interaction existed between SLC25a3 and Nsp15, and SLC25a3 significantly inhibited PEDV replication in a dose-dependent manner. SLC25a3 inhibits PEDV replication. The results of this study provide a basis for deciphering the role and mechanism of SLC25a3 in the host immune response to PEDV infection.
Porcine epidemic diarrhea virus/genetics* ; Viral Nonstructural Proteins/metabolism* ; Animals ; Swine ; Virus Replication ; Coronavirus Infections/veterinary* ; Swine Diseases/metabolism*

Porcine epidemic diarrhea virus (PEDV) is a highly pathogenic virus that can cause acute intestinal infectious diseases in both piglets and fattening pigs. The virus encodes at least 16 non-structural proteins, including nsp9, which has been shown to bind to single-stranded RNA. However, its function and mechanism remain unclear. In this study, we aimed to identify potential host proteins that interact with PEDV nsp9 using immunoprecipitation combined with mass spectrometry. The interactions were then confirmed by co-immunoprecipitation (Co-IP) and confocal laser scanning fluorescence techniques. The results showed that nsp9 interacts with HSPA8, Tollip, HSPA9 and TOMM70. Among them, overexpression of HSPA8 resulted in caused first upregulated and then down-regulated expression of nsp9, and promoted the proliferation of PEDV. Overexpression of Tollip significantly upregulated the expression of nsp9 and inhibited the proliferation of PEDV. Overexpression of TOMM70 significantly reduced the expression of nsp9, but did not show significant effect on the proliferation of PEDV. Overexpression of HSPA9 did not show significant effect on the expression of nsp9 and the proliferation of PEDV. These findings may facilitate further investigating the role of nsp9-interacting proteins in PEDV infection.
Animals ; Swine ; Porcine epidemic diarrhea virus/genetics* ; Virus Replication ; Proteins ; Swine Diseases

Porcine epidemic diarrhea (PED) is a major disease of pigs that inflicts heavy losses on the global pig industry. The etiologic agent is the porcine epidemic diarrhea virus (PEDV), which is assigned to the genus Alphacoronavirus in the family Coronaviridae. This review consists of five parts, the first of which provides a brief introduction to PEDV and its epidemiology. Part two outlines the passive immunity in new born piglets and the important role of colostrum, while the third part summarizes the characteristics of the immune systems of pregnant sows, discusses the concept of the "gut-mammary gland-secretory IgA(sIgA) axis" and the possible underpinning mechanisms, and proposes issues to be addressed when designing a PEDV live vaccine. The final two parts summarizes the advances in the R&D of PEDV vaccines and prospects future perspectives on prevention and control of PEDV, respectively.
Animals ; Antibodies, Viral ; Coronavirus Infections/veterinary* ; Female ; Immunization ; Porcine epidemic diarrhea virus ; Pregnancy ; Swine ; Swine Diseases/prevention & control* ; Viral Vaccines

To investigate whether the engineered Lactobacillus plantarum expressing the porcine epidemic diarrhea virus (PEDV) S1 gene can protect animals against PEDV, guinea pigs were fed with recombinant L. plantarum containing plasmid PVE5523-S1, with a dose of 2×10⁸ CFU/piece, three times a day, at 14 days intervals. Guinea pigs fed with wild type L. plantarum and the engineered L. plantarum containing empty plasmid pVE5523 were used as negative controls. For positive control, another group of guinea pigs were injected with live vaccine for porcine epidemic diarrhea and porcine infectious gastroenteritis (HB08+ZJ08) by intramuscular injection, with a dose of 0.2 mL/piece, three times a day, at 14 days intervals. Blood samples were collected from the hearts of the four groups of guinea pigs at 0 d, 7 d, 14 d, 24 d, 31 d, 41 d and 48 d, respectively, and serum samples were isolated for antibody detection and neutralization test analysis by enzyme-linked immunosorbent assay (ELISA). The spleens of guinea pigs were also aseptically collected to perform spleen cells proliferation assay. The results showed that the engineered bacteria could stimulate the production of secretory antibody sIgA and specific neutralizing antibody, and stimulate the increase of IL-4 and IFN-γ, as well as the proliferation of spleen cells. These results indicated that the engineered L. plantarum containing PEDV S1 induced specific immunity toward PEDV in guinea pigs, which laid a foundation for subsequent oral vaccine development.
Animals ; Antibodies, Viral ; Coronavirus Infections/veterinary* ; Guinea Pigs ; Lactobacillus plantarum/genetics* ; Porcine epidemic diarrhea virus/genetics* ; Swine ; Swine Diseases ; Viral Vaccines/genetics*

The aim of this study was to develop a blocking enzyme-linked immunosorbent assay (bELISA) based on a biotinylated nanobody target the S1 protein of porcine epidemic diarrhea virus (PEDV) for detecting the anti-PEDV antibodies and evaluating the immune effect of the vaccine. The gene encoding the single-domain antibody sdAb3 target the PEDV S1 protein was amplified and the Avitag sequence was fused at its 3'-end. The PCR product was cloned into the expression vector pET-21b for expression and purification of the sdAb3-Avitag protein. The purified sdAb3-Avitag fusion protein was biotinylated and its activity was determined. Using the recombinant S1 protein as a coating antigen, a bELISA was established and optimized. Serum samples were tested in parallel by the bELISA and a commercial kit. The recombinant vector pET21b-sdAb3-Avitag was constructed to express the tagged sdAb3. After induction for expression, the biotin-labeled sdAb3 (sdAb3-Biotin) with high purity and good activity was obtained. For the optimized bELISA, the coating concentration of the S1 protein was 200 ng/well, the serum dilution was 1:2 and incubated for 2 h, the dilution ratio of the biotinylated sdAb3 was 1:8 000 and incubated for 30 min, the dilution of the enzyme-labeled antibody was 1:5 000 and incubated for 30 min. The bELISA had no cross reaction with the sera of major porcine viruses including transmissible gastroenteritis virus, porcine reproductive and respiratory syndrome virus and showed good specificity and reproducibility. For a total of 54 porcine serum samples tested, the overall compliance rate of the bELISA with a commercial kit was 92.56%. This study developed a rapid and reliable bELISA method, which can be used for serosurveillance and vaccine evaluation for PEDV.
Animals ; Antibodies, Viral ; Coronavirus Infections/veterinary* ; Enzyme-Linked Immunosorbent Assay ; Porcine epidemic diarrhea virus/genetics* ; Reproducibility of Results ; Sensitivity and Specificity ; Single-Domain Antibodies ; Swine ; Swine Diseases

ORF3 protein, the single accessory protein encoded by porcine epidemic diarrhea virus (PEDV), is related to viral pathogenicity. In order to determine the cytoplasmic location signal of PEDV ORF3, we constructed a series of recombinant plasmids carrying full-length or truncated segments of PEDV DR13 ORF3 protein. When the acquired plasmids were transfected into Vero cells, expression and distribution of the EGFP-fused full-length ORF3 protein and its truncated forms in the cells were observed by laser confocal microscopy. The results showed that ORF3 protein or their truncated forms containing 40-91 aa segment including two transmembrane domains were localized in the cytoplasm, whereas ORF3 truncated peptides without the 40-91 aa segment were distributed in the whole cell (in both cytoplasm and nucleus). This suggests that the 40-91 aa is the key structural domain determining cytoplasmic location of PEDV ORF3 protein. The discovery provides reference for further clarifying intracellular transport and biological function of PEDV ORF3 protein.
Amino Acid Sequence ; Animals ; Chlorocebus aethiops ; Coronavirus Infections ; virology ; Cytoplasm ; virology ; Porcine epidemic diarrhea virus ; genetics ; Protein Domains ; Swine ; Vero Cells ; Viral Proteins ; chemistry ; metabolism

The recent emergence and re-emergence of porcine epidemic diarrhea virus (PEDV) underscore the urgent need for the development of novel, safe, and effective vaccines against the prevailing strain. In this study, we generated a cold-adapted live attenuated vaccine candidate (Aram-P29-CA) by short-term passage of a virulent PEDV isolate at successively lower temperatures in Vero cells. Whole genome sequencing identified 12 amino acid changes in the cold-adapted strain with no insertions and deletions throughout the genome. Animal inoculation experiments confirmed the attenuated phenotype of Aram-P29-CA virus in the natural host. Pregnant sows were orally administered P29-CA live vaccines two doses at 2-week intervals prior to parturition, and the newborn piglets were challenged with the parental virus. The oral homologous prime-boost vaccination of P29-CA significantly improved the survival rate of the piglets and notably mitigated the severity of diarrhea and PEDV fecal shedding after the challenge. Furthermore, strong antibody responses to PEDV were detected in the sera and colostrum of immunized sows and in the sera of their offspring. These results demonstrated that the cold-adapted attenuated virus can be used as a live vaccine in maternal vaccination strategies to provide durable lactogenic immunity and confer passive protection to litters against PEDV.
Animals ; Antibody Formation ; Colostrum ; Diarrhea ; Genome ; Genotype ; Humans ; Infant, Newborn ; Parents ; Parturition ; Phenotype ; Porcine epidemic diarrhea virus ; Survival Rate ; Vaccination ; Vaccines ; Vero Cells

Porcine epidemic diarrhea (PED) is a highly contagious enteric swine disease. The large economic impact of PED on the swine industry worldwide has made the development of an effective PED vaccine a necessity. S0, a truncated region of the porcine epidemic diarrhea virus (PEDV) spike protein, has been suggested as a candidate antigen for PED subunit vaccines; however, poor solubility problems when the protein is expressed in Escherichia coli, and the inherent problems of subunit vaccines, such as low immunogenicity, remain. Flagellin has been widely used as a fusion partner to enhance the immunogenicity and solubility of many difficult-to-express proteins; however, the conjugation effect of flagellin varies depending on the target antigen or the position of the fusion placement. Here, we conjugated flagellin, Vibrio vulnificus FlaB, to the N- and C-termini of S0 and evaluated the ability of the fusion to enhance the solubility and immunogenicity of S0. Flagellin conjugation in the presence of the trigger factor chaperone tig greatly improved the solubility of the fusion protein (up to 99%) regardless of its conjugation position. Of importance, flagellin conjugated to the N-terminus of S0 significantly enhanced S0-specific humoral immune responses compared to other recombinant antigens in Balb/c mice. The mechanism of this phenomenon was investigated through in vitro and in vivo studies. These findings provide important information for the development of a novel PED vaccine and flagellin-based immunotherapeutics.
Animals ; Diarrhea ; Escherichia coli ; Flagellin ; Immunity, Humoral ; In Vitro Techniques ; Mice ; Porcine epidemic diarrhea virus ; Solubility ; Swine ; Swine Diseases ; Vaccines, Subunit ; Vibrio vulnificus ; Vibrio

Porcine epidemic diarrhea virus (PEDV) is a contagious coronavirus infecting pigs that leads to significant economic losses in the swine industry. Given that PEDV infection occurs in gut epithelial cells mainly via the fecal-oral route, induction of PEDV-specific immune responses in the mucosal compartment is required for protective immunity against viral infection. However, an effective mucosal vaccine against the currently prevalent PEDV strain is not available. In this study, we demonstrated that the N-terminal domain (NTD) of the spike (S) protein of PEDV represents a new vaccine candidate molecule to be applied via the mucosal route. We first established an Escherichia coli expression system producing the partial NTD (NTD231–501) of the PEDV S protein. Orally administered NTD231–501 protein specifically interacted with the apical area of M cells in the follicle-associated epithelium of Peyer's patch. Additionally, the NTD protein induced antigen-specific immune responses in both the systemic and mucosal immune compartments when administered orally. Collectively, we propose the NTD of the PEDV S protein to be a candidate mucosal vaccine molecule.
Coronavirus ; Epithelial Cells ; Epithelium ; Escherichia coli ; Immunity, Mucosal ; Porcine epidemic diarrhea virus* ; Swine