Gene Variations in Cis-Acting Elements between the Taiwan and Prototype Strains of Porcine Epidemic Diarrhea Virus Alter Viral Gene Expression

In 2013, the outbreak of porcine epidemic diarrhea (PED) in Taiwan caused serious economic losses. In this study, we examined whether the variations of the cis-acting elements between the porcine epidemic diarrhea virus (PEDV) Taiwan (TW) strain and the prototype strain CV777 alter gene expression. For this aim, we analyzed the variations of the cis-acting elements in the 5’ and 3’ untranslated regions (UTRs) between the PEDV TW, CV777, and other reference strains. We also determined the previously unidentified transcription regulatory sequence (TRS), a sequence motif required for coronavirus transcription, and found that a nucleotide deletion in the TW strain, in comparison with CV777 strain, immediately downstream of the leader core sequence alters the identity between the leader TRS and the body TRS. Functional analyses using coronavirus defective interfering (DI) RNA revealed that such variations in cis-acting elements for the TW strain compared with the CV777 strain have an influence on the efficiency of gene expression. The current data show for the first time the evolution of PEDV in terms of cis-acting elements and their effects on gene expression, and thus may contribute to our understanding of recent PED outbreaks worldwide.

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Structural Basis for the Inhibition of Host Gene Expression by Porcine Epidemic Diarrhea Virus nsp1

Journal of Virology ◽

10.1128/jvi.01896-17 ◽

2017 ◽

Vol 92 (5) ◽

Cited By ~ 10

Author(s):

Zhou Shen ◽

Gang Ye ◽

Feng Deng ◽

Gang Wang ◽

Min Cui ◽

...

Keyword(s):

Gene Expression ◽

Porcine Epidemic Diarrhea Virus ◽

Host Gene ◽

Structural Basis ◽

Economic Losses ◽

Host Gene Expression ◽

Functional Region ◽

Content Type ◽

Diarrhea Virus ◽

Porcine Epidemic Diarrhea

ABSTRACT Porcine epidemic diarrhea virus (PEDV), an enteropathogenic Alphacoronavirus , has caused enormous economic losses in the pork industry. Nonstructural protein 1 (nsp1) is a characteristic feature of alpha- and betacoronaviruses, which exhibits both functional conservation and mechanistic diversity in inhibiting host gene expression and antiviral responses. However, the detailed structure and molecular mechanisms underlying the Alphacoronavirus nsp1 inhibition of host gene expression remain unclear. Here, we report the first full-length crystal structure of Alphacoronavirus nsp1 from PEDV. The structure displays a six-stranded β-barrel fold in the middle of two α-helices. The core structure of PEDV nsp1 shows high similarity to those of severe acute respiratory syndrome coronavirus (SARS-CoV) nsp1 and transmissible gastroenteritis virus (TGEV) nsp1, despite its low degree of sequence homology. Using ribopuromycylation and Renilla luciferase reporter assays, we showed that PEDV nsp1 can dramatically inhibit general host gene expression. Furthermore, three motifs (amino acids [aa] 67 to 71, 78 to 85, and 103 to 110) of PEDV nsp1 create a stable functional region for inhibiting protein synthesis, differing considerably from Betacoronavirus nsp1. These results elucidate the detailed structural basis through which PEDV nsp1 inhibits host gene expression, providing insight into the development of a new attenuated vaccine with nsp1 modifications. IMPORTANCE Porcine epidemic diarrhea virus (PEDV) has led to tremendous economic losses in the global swine industry. PEDV nsp1 plays a crucial role in inhibiting host gene expression, but its functional mechanism remains unclear. Here, we report the full-length structure of PEDV nsp1, the first among coronaviruses to be reported. The 1.25-Å resolution crystal structure of PEDV nsp1 shows high similarity to severe acute respiratory syndrome coronavirus (SARS-CoV) nsp1 13–128 and transmissible gastroenteritis virus (TGEV) nsp1 1–104 , despite a lack of sequence homology. Structural and biochemical characterization demonstrated that PEDV nsp1 possesses a stable functional region for inhibition of host protein synthesis, which is formed by loops at residues 67 to 71, 78 to 85, and 103 to 110. The different functional regions in PEDV nsp1 and SARS-CoV nsp1 may explain their distinct mechanisms. Importantly, our structural data are conducive to understanding the mechanism of PEDV nsp1 inhibition of the expression of host genes and may aid in the development of a new attenuated vaccine.

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Engineering a Live Attenuated Porcine Epidemic Diarrhea Virus Vaccine Candidate via Inactivation of the Viral 2'-O-Methyltransferase and the Endocytosis Signal of the Spike Protein

Journal of Virology ◽

10.1128/jvi.00406-19 ◽

2019 ◽

Vol 93 (15) ◽

Cited By ~ 10

Author(s):

Yixuan Hou ◽

Hanzhong Ke ◽

Jineui Kim ◽

Dongwan Yoo ◽

Yunfang Su ◽

...

Keyword(s):

Porcine Epidemic Diarrhea Virus ◽

Vaccine Development ◽

Vaccine Candidate ◽

Spike Protein ◽

Economic Losses ◽

High Dose ◽

Type I ◽

Viral Pathogen ◽

Diarrhea Virus ◽

Porcine Epidemic Diarrhea

ABSTRACT Porcine epidemic diarrhea virus (PEDV) causes high mortality in neonatal piglets; however, effective and safe vaccines are still not available. We hypothesized that inactivation of the 2′-O-methyltransferase (2′-O-MTase) activity of nsp16 and the endocytosis signal of the spike protein attenuates PEDV yet retains its immunogenicity in pigs. We generated a recombinant PEDV, KDKE4A, with quadruple alanine substitutions in the catalytic tetrad of the 2′-O-MTase using a virulent infectious cDNA clone, icPC22A, as the backbone. Next, we constructed another mutant, KDKE4A-SYA, by abolishing the endocytosis signal of the spike protein of KDKE4A. Compared with icPC22A, the KDKE4A and KDKE4A-SYA mutants replicated less efficiently in vitro but induced stronger type I and type III interferon responses. The pathogenesis and immunogenicities of the mutants were evaluated in gnotobiotic piglets. The virulence of KDKE4A-SYA and KDKE4A was significantly reduced compared with that of icPC22A. Mortality rates were 100%, 17%, and 0% in the icPC22A-, KDKE4A-, and KDKE4A-SYA-inoculated groups, respectively. At 21 days postinoculation (dpi), all surviving pigs were challenged orally with a high dose of icPC22A. The KDKE4A-SYA- and KDKE4A-inoculated pigs were protected from the challenge, because no KDKE4A-SYA- and one KDKE4A-inoculated pig developed diarrhea whereas all the pigs in the mock-inoculated group had severe diarrhea, and 33% of them died. Furthermore, we serially passaged the KDKE4A-SYA mutant in pigs three times and did not find any reversion of the introduced mutations. The data suggest that KDKE4A-SYA may be a PEDV vaccine candidate. IMPORTANCE PEDV is the most economically important porcine enteric viral pathogen and has caused immense economic losses in the pork industries in many countries. Effective and safe vaccines are desperately required but still not available. 2′-O-MTase (nsp16) is highly conserved among coronaviruses (CoVs), and the inactivation of nsp16 in live attenuated vaccines has been attempted for several betacoronaviruses. We show that inactivation of both 2′-O-MTase and the endocytosis signal of the spike protein is an approach to designing a promising live attenuated vaccine for PEDV. The in vivo passaging data also validated the stability of the KDKE4A-SYA mutant. KDKE4A-SYA warrants further evaluation in sows and their piglets and may be used as a platform for further optimization. Our findings further confirmed that nsp16 can be a universal target for CoV vaccine development and will aid in the development of vaccines against other emerging CoVs.

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Investigation of the Role of the Spike Protein in Reversing the Virulence of the Highly Virulent Taiwan Porcine Epidemic Diarrhea Virus Pintung 52 Strains and Its Attenuated Counterpart

Viruses ◽

10.3390/v12010041 ◽

2019 ◽

Vol 12 (1) ◽

pp. 41 ◽

Cited By ~ 2

Author(s):

Chi-Fei Kao ◽

Hui-Wen Chang

Keyword(s):

Mortality Rate ◽

Porcine Epidemic Diarrhea Virus ◽

Rational Design ◽

Economic Losses ◽

Diarrhea Virus ◽

Viral Shedding ◽

S Gene ◽

Porcine Epidemic Diarrhea ◽

Highly Virulent

Porcine epidemic diarrhea virus (PEDV) has continuously caused severe economic losses to the global swine industries; however, no successful vaccine against PEDV has been developed. In this study, we generated four autologous recombinant viruses, including the highly virulent iPEDVPT-P5, attenuated iPEDVPT-P96, and two chimeric viruses (iPEDVPT-P5-96S and iPEDVPT-P96-5S) with the reciprocally exchanged spike (S) gene, to study the role of the S gene in PEDV pathogenesis. A deeper understanding of PEDV attenuation will aid in the rational design of a live attenuated vaccine (LAV) using reverse genetics system. Our results showed that replacing the S gene from the highly virulent iPEDVPT-P5 led to complete restoration of virulence of the attenuated iPEDVPT-P96, with nearly identical viral shedding, diarrhea pattern, and mortality rate as the parental iPEDVPT-P5. In contrast, substitution of the S gene with that from the attenuated iPEDVPT-P96 resulted in partial attenuation of iPEDVPT-P5, exhibiting similar viral shedding and diarrhea patterns as the parental iPEDVPT-P96 with slightly severe histological lesions and higher mortality rate. Collectively, our data confirmed that the attenuation of the PEDVPT-P96 virus is primarily attributed to mutations in the S gene. However, mutation in S gene alone could not fully attenuate the virulence of iPEDVPT-P5. Gene (s) other than S gene might also play a role in determining virulence.

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A novel biotinylated nanobody-based blocking ELISA for the rapid and sensitive clinical detection of porcine epidemic diarrhea virus

Journal of Nanobiotechnology ◽

10.1186/s12951-019-0531-x ◽

2019 ◽

Vol 17 (1) ◽

Cited By ~ 4

Author(s):

Zhiqian Ma ◽

Tianyu Wang ◽

Zhiwei Li ◽

Xuyang Guo ◽

Yangsheng Tian ◽

...

Keyword(s):

Phage Display ◽

Porcine Epidemic Diarrhea Virus ◽

Diagnostic Methods ◽

Watery Diarrhea ◽

Economic Losses ◽

Serum Samples ◽

Phage Display Technology ◽

Diarrhea Virus ◽

Blocking Elisa ◽

Porcine Epidemic Diarrhea

Abstract Background Porcine epidemic diarrhea virus (PEDV), which is characterized by severe watery diarrhea, vomiting, dehydration and a high mortality rate in piglets, leads to enormous economic losses to the pork industry and remains a large challenge worldwide. Thus, a rapid and reliable method is required for epidemiological investigations and to evaluate the effect of immunization. However, the current diagnostic methods for PEDV are time-consuming and very expensive and rarely meet the requirements for clinical application. Nanobodies have been used in the clinic to overcome these problems because of the advantages of their easy expression and high level of stability. In the present work, a novel biotinylated nanobody-based blocking ELISA (bELISA) was developed to detect anti-PEDV antibodies in clinical pig serum. Results Using phage display technology and periplasmic extraction ELISA (PE-ELISA), anti-PEDV N protein nanobodies from three strains of PEDV were successfully isolated after three consecutive rounds of bio-panning from a high quality phage display VHH library. Then, purified Nb2-Avi-tag fusion protein was biotinylated in vitro. A novel bELISA was subsequently developed for the first time with biotinylated Nb2. The cutoff value for bELISA was 29.27%. One hundred and fifty clinical serum samples were tested by both newly developed bELISA and commercial kits. The sensitivity and specificity of bELISA were 100% and 93.18%, respectively, and the coincidence rate between the two methods was 94%. Conclusions In brief, bELISA is a rapid, low-cost, reliable and useful nanobody-based tool for the serological evaluation of current PEDV vaccines efficacy and indirect diagnosis of PEDV infection.

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Development of indirect enzyme-linked immunosorbent assay for detection of porcine epidemic diarrhea virus specific antibodies (IgG) in serum of naturally infected pigs

BMC Veterinary Research ◽

10.1186/s12917-019-2123-2 ◽

2019 ◽

Vol 15 (1) ◽

Cited By ~ 1

Author(s):

Ohnmar Myint ◽

Ayako Yoshida ◽

Satoshi Sekiguchi ◽

Nguyen Van Diep ◽

Naoyuki Fuke ◽

...

Keyword(s):

Sensitivity And Specificity ◽

High Mortality ◽

Porcine Epidemic Diarrhea Virus ◽

Indirect Elisa ◽

Neutralization Test ◽

Elisa Test ◽

Watery Diarrhea ◽

Economic Losses ◽

Diarrhea Virus ◽

Porcine Epidemic Diarrhea

Abstract Background Porcine epidemic diarrhea virus (PEDV) infection is a highly contagious infectious disease causing watery diarrhea, vomiting, dehydration and high mortality rate in newborn piglets. PEDV infection can cause high economic losses in pig industry. In Japan, a PEDV outbreak occurred with high mortality from 2013 to 2015. Even though until now, PEDV infection occurs sporadically. For the control and monitoring of PEDV infection, not only symptomatic pigs, but also asymptomatic pigs should be identified. The objective of this study is to develop and optimize novel indirect ELISA as a simple, rapid, sensitive and specific method for the detection of anti-PEDV antibodies and evaluate the efficacy of the assay as a diagnostic method for PED. Results One hundred sixty-two serum samples, consisting of 81 neutralization test (NT) positive and 81 NT negative sera, were applied to the assay. Indirect ELISA test based on whole virus antigen (NK94P6 strain) derived from Vero cell culture was evaluated by receiver operating characteristic (ROC) analysis with neutralization test (NT) as a reference method, and cut-off value was determined as 0.320 with sensitivity and specificity of 92.6 and 90.1%, respectively. The area under curve (AUC) was 0.949, indicating excellent accuracy of indirect ELISA test. There was significant positive correlation between indirect ELISA and neutralization test (R = 0.815, P < 0.05). Furthermore, the kappa statics showed the excellent agreement between these two tests (kappa value = 0.815). In addition, the sensitivity and specificity of preserved plates with different periods (1 day, 2 weeks, 1, 2, 3, 4, 5 and 6 months) after drying antigen coated plates were 100% and 80–100%, respectively. Conclusions The developed indirect ELISA test in our study would be useful as a reliable test for serological survey and disease control of PEDV infection, and our pre-antigen coated ELISA plates can be preserved at 4 °C until at least 6 months.

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Characterization and pathogenicity of Vero cell-attenuated porcine epidemic diarrhea virus CT strain

Virology Journal ◽

10.1186/s12985-019-1232-7 ◽

2019 ◽

Vol 16 (1) ◽

Cited By ~ 2

Author(s):

Yu Wu ◽

Wei Li ◽

Qingfeng Zhou ◽

Qunhui Li ◽

Zhichao Xu ◽

...

Keyword(s):

Porcine Epidemic Diarrhea Virus ◽

Clinical Symptoms ◽

Vero Cells ◽

Economic Losses ◽

Protective Effects ◽

Diarrhea Virus ◽

Cytopathic Effects ◽

Porcine Epidemic Diarrhea ◽

Piglet Survival

Abstract Background Porcine epidemic diarrhea virus (PEDV) has caused enormous economic losses to the global pig industry. Currently available PEDV vaccine strains have limited protective effects against PEDV variant strains. Methods In this study, the highly virulent epidemic virus strain CT was serially passaged in Vero cells for up to 120 generations (P120). Characterization of the different passages revealed that compared with P10 and P64, P120 had a higher viral titer and more obvious cytopathic effects, thereby demonstrating better cell adaptability. Results Pathogenicity experiments using P120 in piglets revealed significant reductions in clinical symptoms, histopathological lesions, and intestinal PEDV antigen distribution; the piglet survival rate in the P120 group was 100%. Furthermore, whole-genome sequencing identified 13 amino acid changes in P120, which might be responsible for the attenuated virulence of P120. Conclusions Thus, an attenuated strain was obtained via cell passaging and that this strain could be used in preparing attenuated vaccines.

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A Comprehensive View on the Host Factors and Viral Proteins Associated With Porcine Epidemic Diarrhea Virus Infection

Frontiers in Microbiology ◽

10.3389/fmicb.2021.762358 ◽

2021 ◽

Vol 12 ◽

Author(s):

Yi Hu ◽

Xiaohong Xie ◽

Lingchen Yang ◽

Aibing Wang

Keyword(s):

Virus Infection ◽

Porcine Epidemic Diarrhea Virus ◽

Molecular Mechanisms ◽

Viral Proteins ◽

Host Factors ◽

Watery Diarrhea ◽

Economic Losses ◽

Target Cells ◽

Diarrhea Virus ◽

Porcine Epidemic Diarrhea

Porcine epidemic diarrhea virus (PEDV), a coronavirus pathogen of the pig intestinal tract, can cause fatal watery diarrhea in piglets, thereby causing huge economic losses to swine industries around the world. The pathogenesis of PEDV has intensively been studied; however, the viral proteins of PEDV and the host factors in target cells, as well as their interactions, which are the foundation of the molecular mechanisms of viral infection, remain to be summarized and updated. PEDV has multiple important structural and functional proteins, which play various roles in the process of virus infection. Among them, the S and N proteins play vital roles in biological processes related to PEDV survival via interacting with the host cell proteins. Meanwhile, a number of host factors including receptors are required for the infection of PEDV via interacting with the viral proteins, thereby affecting the reproduction of PEDV and contributing to its life cycle. In this review, we provide an updated understanding of viral proteins and host factors, as well as their interactions in terms of PEDV infection. Additionally, the effects of cellular factors, events, and signaling pathways on PEDV infection are also discussed. Thus, these comprehensive and profound insights should facilitate for the further investigations, control, and prevention of PEDV infection.

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Molecular Characteristics and Pathogenicity of Porcine Epidemic Diarrhea Virus Isolated in Some Areas of China in 2015–2018

Frontiers in Veterinary Science ◽

10.3389/fvets.2020.607662 ◽

2020 ◽

Vol 7 ◽

Author(s):

Linyang Yu ◽

Yanling Liu ◽

Shuangyun Wang ◽

Leyi Zhang ◽

Pengshuai Liang ◽

...

Keyword(s):

Porcine Epidemic Diarrhea Virus ◽

Vero Cells ◽

Economic Losses ◽

Molecular Characteristics ◽

Phylogenetic Tree Analysis ◽

Genetic Characteristics ◽

Diarrhea Virus ◽

Severe Diarrhea ◽

Positive Rate ◽

Porcine Epidemic Diarrhea

Since 2010, Porcine epidemic diarrhea virus (PEDV) has caused severe diarrhea disease in piglets in China, resulting in large economic losses. To understand the genetic characteristics of the PEDV strains that circulated in some provinces of China between 2015 and 2018, 375 samples of feces and small intestine were collected from pigs and tested. One hundred seventy-seven samples tested positive and the PEDV-positive rate was 47.20%. A phylogenetic tree analysis based on the entire S gene showed that these strains clustered into four subgroups, GI-a, GI-b, GII-a, and GII-b, and that the GII-b strains have become dominant in recent years. Compared with previous strains, these strains have multiple variations in the SP and S1-NTD domains and in the neutralizing epitopes of the S protein. We also successfully isolated and identified a new virulent GII-b strain, GDgh16, which is well-adapted to Vero cells and caused a high mortality rate in piglets in challenge experiments. Our study clarifies the genetic characteristics of the prevalent PEDV strains in parts of China, and suggests that the development of effective novel vaccines is both necessary and urgent.

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Successive Passage In Vitro Led to Lower Virulence and Higher Titer of A Variant Porcine Epidemic Diarrhea Virus

Viruses ◽

10.3390/v12040391 ◽

2020 ◽

Vol 12 (4) ◽

pp. 391 ◽

Cited By ~ 1

Author(s):

Pengwei Zhao ◽

Song Wang ◽

Zhi Chen ◽

Jiang Yu ◽

Rongzhi Tang ◽

...

Keyword(s):

Amino Acids ◽

Porcine Epidemic Diarrhea Virus ◽

Vero Cells ◽

Economic Losses ◽

Diarrhea Virus ◽

S Gene ◽

Successive Passage ◽

Porcine Epidemic Diarrhea

A highly virulent porcine epidemic diarrhea virus (PEDV) appeared in China and spread rapidly to neighbor countries, which have led to great economic losses to the pig industry. In the present study, we isolated a PEDV using Vero cells and serially propagated 100 passages. PEDV SDSX16 was characterized in vitro and in vivo. The viral titers increased to 107.6 TCID50/mL (100th) by serial passages. The spike (S) gene and the whole gene of the SDSX16 virus was fully sequenced to assess the genetic stability and relatedness to previously identified PEDV. Along with successive passage in vitro, there were 18 nucleotides (nt) deletion occurred in the spike (S) gene resulting in a deletion of six amino acids when the SDSX16 strain was passaged to the 64th generation, and this deletion was stable until the P100. However, the ORF1a/b, M, N, E, and ORF3 genes had only a few point mutations in amino acids and no deletions. According to growth kinetics experiments, the SDSX16 deletion strain significantly enhanced its replication in Vero cells since it was passaged to the 64th generation. The animal studies showed that PEDV SDSX16-P10 caused more severe diarrhea and vomiting, fecal shedding, and acute atrophic enteritis than SDSX16-P75, indicating that SDSX16-P10 is enteropathogenic in the natural host, and the pathogenicity of SDSX16 decreased with successive passage in vitro. However, SDSX16-P10 was found to cause lower levels of cytokine expression than SDSX16-P75 using real-time PCR and flow cytometry, such as IL1β, IL6, IFN-β, TNF-α, indicating that SDSX16-P10 might inhibit the expression of cytokines. Our data indicated that successive passage in vitro resulted in virulent attenuation in vivo of the PEDV variant strain SDSX16.

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Tomatidine inhibits porcine epidemic diarrhea virus replication by targeting 3CL protease

Veterinary Research ◽

10.1186/s13567-020-00865-y ◽

2020 ◽

Vol 51 (1) ◽

Author(s):

Pengcheng Wang ◽

Juan Bai ◽

Xuewei Liu ◽

Mi Wang ◽

Xianwei Wang ◽

...

Keyword(s):

Porcine Epidemic Diarrhea Virus ◽

Economic Losses ◽

Titration Calorimetry ◽

Respiratory Syndrome Virus ◽

Transmissible Gastroenteritis Virus ◽

Diarrhea Virus ◽

Infected Cells ◽

Porcine Epidemic Diarrhea ◽

3Cl Protease

Abstract Porcine epidemic diarrhea virus (PEDV) causes lethal diarrhea in suckling piglets, leading to severe economic losses worldwide. There is an urgent need to find new therapeutic methods to prevent and control PEDV. Not only is there a shortage of commercial anti-PEDV drugs, but available commercial vaccines fail to protect against highly virulent PEDV variants. We screened an FDA-approved library of 911 natural products and found that tomatidine, a steroidal alkaloid extracted from the skin and leaves of tomatoes, demonstrates significant inhibition of PEDV replication in Vero and IPEC-J2 cells in vitro. Molecular docking and molecular dynamics analysis predicted interactions between tomatidine and the active pocket of PEDV 3CL protease, which were confirmed by fluorescence spectroscopy and isothermal titration calorimetry (ITC). The inhibiting effect of tomatidine on 3CL protease was determined using cleavage visualization and FRET assay. Tomatidine-mediated blocking of 3CL protease activity in PEDV-infected cells was examined by western blot detection of the viral polyprotein in PEDV-infected cells. It indicates that tomatidine inhibits PEDV replication mainly by targeting 3CL protease. In addition, tomatidine also has antiviral activity against transmissible gastroenteritis virus (TGEV), porcine reproductive and respiratory syndrome virus (PRRSV), encephalo myocarditis virus (EMCV) and seneca virus A (SVA) in vitro. These results may be helpful in developing a new prophylactic and therapeutic strategy against PEDV and other swine disease infections.

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