Porcine Epidemic Diarrhea Outbreaks Research Articles

New Chimeric Porcine Coronavirus in Swine Feces, Germany, 2012 [Letter

Porcine epidemic diarrhea virus (PEDV) and transmissible gastroenteritis virus (TGEV) can cause severe enteritis in pigs accompanied by diarrhea, vomiting, and dehydration. Clinical signs are most prominent in young suckling pigs, in which high mortality rates are common. As seen in recent porcine epidemic diarrhea outbreaks in the United States and Asia, the effect on the pig industry can be tremendous. [...]

Using heterogeneity in the population structure of U.S. swine farms to compare transmission models for porcine epidemic diarrhoea.

In 2013, U.S. swine producers were confronted with the disruptive emergence of porcine epidemic diarrhoea (PED). Movement of animals among farms is hypothesised to have played a role in the spread of PED among farms. Via this or other mechanisms, the rate of spread may also depend on the geographic density of farms and climate. To evaluate such effects on a large scale, we analyse state-level counts of outbreaks with variables describing the distribution of farm sizes and types, aggregate flows of animals among farms, and an index of climate. Our first main finding is that it is possible for a correlation analysis to be sensitive to transmission model parameters. This finding is based on a global sensitivity analysis of correlations on simulated data that included a biased and noisy observation model based on the available PED data. Our second main finding is that flows are significantly associated with the reports of PED outbreaks. This finding is based on correlations of pairwise relationships and regression modeling of total and weekly outbreak counts. These findings illustrate how variation in population structure may be employed along with observational data to improve understanding of disease spread.

Collection and review of updated scientific epidemiological data on porcine epidemic diarrhoea.

Porcine epidemic diarrhoea (PED) is a non‐zoonotic viral disease of pigs caused by a coronavirus and characterised by watery diarrhoea and weight loss. PED is not notifiable to the EU or World Organisation for Animal Health listed but it is notifiable at the national level in Finland, France, Ireland and Sweden. PED case reports from seven countries and PED surveillance and monitoring activities in thirteen countries were reported. This information was combined with an extensive literature review to provide an update on global PED occurrence, circulating strains and impact in 2014–2015. PED confirmed cases have been reported in North America, South America, Asia and Europe. PED virus (PEDV) sequences originating from EU pig herds indicate that the strains currently in circulation share nearly 100% sequence identity and have greater than 99% sequence identity with the reference INDEL (insertion/deletion) strain USA/OH851/2014. In 2014–2015, greater genetic variability has been reported in strains circulating in Asia compared with EU Member States and a non‐INDEL strain has been detected in the Ukraine in 2014. Data on impact confirms that mortality is higher in suckling piglets and diarrhoea is observed in all age groups. The reported impact is in agreement with that reported in EFSA AHAW Panel (2014) indicating that the impact of recently reported PED outbreaks in Asia and the USA seems to be more severe than that described in EU countries, although the impact of different PEDV strains is difficult to compare between one country and another, as impact is dependent not only on pathogenicity but also on factors such as biosecurity, herd size, farm management, sanitary status or herd immune status.

The role of porcine reproductive and respiratory syndrome virus as a risk factor in the outbreak of porcine epidemic diarrhea in immunized swine herds

The aim of the study was to investigate the relation between porcine epidemic diarrhea (PED) and porcine reproductive and respiratory syndrome virus (PRRSV). Here, we constructed a dynamic clinical experimental model in which sows were infected with PRRSV. The stability of the experimental model was surveyed by detecting the levels of antibodies against classical swine fever virus (CSFV) or PRRSV, respectively. In both group A (infected group) and group B (healthy group), the CSFV antibody level was not significantly different (P > 0.05). In group B, the PRRSV antibody level was also not significantly different (P > 0.05) at the three times of testing. The incidence of porcine epidemic diarrhea virus (PEDV) in piglets and PEDV-carrying rate of sows was detected by real-time fluorescent RT-PCR. In group A, PEDV infection of piglets and the PEDV-carrying rate of sows were significantly higher than in group B (P < 0.01) and the PEDV strains were within the same group according to the phylogenetic analysis based on the complete S gene. The results suggested that PRRSV was a risk factor in the outbreak of PED in immunized swine herds. Besides that, the experimental model was stable and no interference factors affected the results of the study.

Impact of a porcine epidemic diarrhea outbreak on swine productivity in Japan: a retrospective cohort study.

The objective was to investigate porcine epidemic diarrhea (PED) outbreak that occurred in 2014 in Japan and its effects on herd-level productivity using a data recording system (PigINFO). The study herds were selected from farrow-to-finish herds (n=99) that entered in the PigINFO system between July 2013 and March 2015. From 1 April to 30 June 2014 (PED epidemic), any herds with clinical signs of PED and feces positive for porcine epidemic diarrhea virus (PEDV) on polymerase chain reaction analysis and/or immunohistochemical staining were defined as PED-positive (n=38). They were further classified into those with long PED periods (L-PED-positive; n=28) and those with short PED periods (S-PED-positive; n=10). Herds with no clinical signs of PED were classified as PED-negative (n=61). Herd-level production data, including preweaning mortality (%; PRWM), postweaning mortality (%; POWM), pigs weaned per litter (PWL), pigs born alive per litter, litters per mated female per year and pigs marketed per sow (MP), were calculated every 3 months during study period. During the PED epidemic, L-PED-positive herds had significantly higher PRWM and POWM than PED-negative herds, and L-PED-positive and S-PED-positive herds had significantly lower PWL. During October–December 2014, L-PED-positive herds had significantly fewer MP than PED-negative herds. The PED outbreak increased mortality and consequently reduced the numbers of marketed pigs. The rapid control of an outbreak is important for reducing the financial losses arising from PED infections.

Porcine Epidemic Diarrhea Virus among Farmed Pigs, Ukraine.

An outbreak of porcine epidemic diarrhea occurred in the summer of 2014 in Ukraine, severely affecting piglets <10 days of age; the mortality rate approached 100%. Full genome sequencing showed the virus to be closely related to strains reported from North America, showing a sequence identity of up to 99.8%.

Epidemiology and vaccine of porcine epidemic diarrhea virus in China: a mini-review.

Porcine epidemic diarrhea (PED) is an intestinal infectious disease caused by porcine epidemic diarrhea virus (PEDV); manifestations of the disease are diarrhea, vomiting and dehydration. Starting from the end of 2010, a PED outbreak occurred in several pig-producing provinces in southern China. Subsequently, the disease spread throughout the country and caused enormous economic losses to the pork industry. Accumulating studies demonstrated that new PEDV variants that appeared in China were responsible for the PED outbreak. In the current mini-review, we summarize PEDV epidemiology and vaccination in China.

Comparative Genomic Analysis of Classical and Variant Virulent Parental/Attenuated Strains of Porcine Epidemic Diarrhea Virus

Since 2010, the variant porcine epidemic diarrhea virus (PEDV) has been the etiological agent responsible for the outbreak of porcine epidemic diarrhea (PED) worldwide. In this study, a variant PEDV strain YN1 was isolated, serially propagated on the Vero cells and was characterized for 200 passages. To better elucidate the molecular basis of Vero cell adaptation of variant PEDV strains, we sequenced, compared, and analyzed the full-genome sequences of parental YN1 and passages 15, 30, 60, 90, 144, and 200. The results showed that the variations increased with the viral passage. The nucleotides sequences of non-structural protein (NSP)2, NSP4-7, NSP10, NSP12 and NSP13 genes did not change during the Vero cell adaptation process. After comparison of the variation characteristic of classical, variant virulent/attenuated strains, it was found that attenuation of PEDV virus was associated with 9−26 amino acid (aa) changes in open reading frames (ORF) 1a/b and S protein, early termination in ORF3, 1–3 aa changes in E, M and N protein and some nucleotide sequences’ synonymous mutations. The aa deletion at about 144 aa of S protein could be the attenuation marker for the PEDV. The pig study showed that the early termination in ORF3 was more important for virus cell adaptation than virus attenuation.

Molecular characterization of pig epidemic diarrhoea viruses isolated in Japan from 2013 to 2014

Since October 2013, approximately 1000 outbreaks of porcine epidemic diarrhoea (PED) have occurred, spanning almost all prefectures of Japan, after a period of seven years without a reported case. In order to consider occurrence factor of PED outbreaks, we determined the whole-genome sequences of 38 PED virus (PEDV) strains from diarrheal samples collected at swine farms in 18 prefectures between 2013 and 2014 using next-generation sequencing technology. Using these data, we investigated genetic variation among the recent Japanese PEDV strains and the genetic relationships between these strains and global PEDV strains isolated recently from multiple swine-industrial countries. Eleven out of 38 PEDV strains were isolated successfully on Vero cells with trypsin treatment and subjected to genome sequence analysis. In a comparative genome analysis, we detected two novel PEDV variants, TTR-2/JPN/2014 and MYG-1/JPN/2014, with large deletions in the spike and ORF3 genes, respectively. A phylogenetic analysis based on the spike gene showed that the 38 Japanese PEDV strains were classified into two PEDV types: the North American type with high virulence (n=34) and the INDEL type (n=4). In addition, the recent Japanese PEDV isolates had a close relationship to global PEDV strains isolated in recent years than to the classical PEDV strains detected in Japan the past decades ago. Moreover, the phylogenetic dendrogram of the complete genomes also indicated that the 38 Japanese PEDV strains, including the two novel PEDV variants discovered in this study, are closely related to the PEDV strains that were widespread in the United States and Korea in 2013–2014. These findings suggest that the re-emergence of PED outbreaks since the last reported case in 2006 was caused by the introduction of recent PEDV strains to Japan from overseas.

Case report describing the clinical course of porcine epidemic diarrhea in a commercial boar stud and return of the stud to service after whole-herd inoculation with porcine epidemic diarrhea virus

In January 2014, an outbreak of porcine epidemic diarrhea (PED) occurred in a PED-naive commercial boar stud. This report documents the outbreak following whole-herd PED virus (PEDV) inoculation with fecal material, cleaning procedures, sentinel exposure, and semen supply to naive sow farms. Boar saliva samples were diagnostically comparable to rectal swabs and collection dummy Swiffer (Proctor and Gamble, Cincinnati, Ohio) samples for PEDV RNA detection. Viral RNA was not detected in semen samples collected during the outbreak, yet reproductive organs from sacrificed boars 5 days after exposure were positive by polymerase chain reaction. Placed sentinel and replacement animals in the stud remained clinically negative following cleaning procedures, and semen shipments started 13 weeks post inoculation (WPI) to one PED-naive sow farm, with six other naive sow farms resuming shipments after 17 WPI. All sow farms remained naive 10 months later. This report demonstrates that it is possible for a commercial boar stud to experience a PED outbreak without infecting naive sow farms at the onset, retain valuable genetics, and resume semen delivery to PED-naive sow farms after cleaning, disinfection, and testing, without infecting sows upon re-opening.

Emergence of porcine epidemic diarrhea virus in southern Germany.

BackgroundOver the last years, porcine epidemic diarrhea virus (PEDV) has caused devastating enteric diseases in the US and several countries in Asia, while outbreaks in Europe have only been reported sporadically since the 1980s. At present, only insufficient information is available on currently circulating PEDV strains in Europe and their impact on the European swine industry. In this case report, we present epidemic outbreaks of porcine epidemic diarrhea in three farms in South-Western Germany.Case presentationEpidemic outbreaks of diarrhea affecting pigs of all age groups were reported in three farms, one fattening farm and two piglet producing farms, in South-Western Germany between May and November 2014. In the fattening farm yellowish, watery diarrhea without evidence of mucus or blood was associated with a massive reduction of feed consumption. Severity of clinical signs and mortality in young suckling pigs varied significantly between the two affected sow farms. While mortality in suckling piglets reached almost 70 % in one sow herd, no increase in suckling piglet mortality was observed in the second sow farm. In all three cases, PEDV was confirmed in feces and small intestines by RT-qPCR. Phylogenetic analyses based on full-length PEDV genomes revealed high identity among strains from all three herds. Moreover, the German strains showed very high nucleotide identity (99.4 %) with a variant of PEDV (OH851) that was isolated in the United States in January 2014. This strain with insertions and deletions in the S-gene (so called INDEL strains) was reported to show lower virulence. Slightly lower identities were found with other strains from the US and Asia.ConclusionPhylogenetic information on the distribution of PEDV strains in Europe is severely lacking. In this case report we demonstrate that acute outbreaks of PEDV occurred in southern Germany in 2014. Current strains were clearly different from isolates found in the 1980s and were closely related to a PEDV variant found in the US in 2014. Moreover, the present case report indicates that variant strains of PEDV, containing insertions and deletions in the S gene, which were reported to be of lower virulence, might be able to cause high mortality in suckling piglets.

A novel pathogenic Mammalian orthoreovirus from diarrheic pigs and Swine blood meal in the United States.

ABSTRACTSince May 2013, outbreaks of porcine epidemic diarrhea have devastated the U.S. swine industry, causing immense economic losses. Two different swine enteric coronaviruses (porcine epidemic diarrhea virus and Delta coronavirus) have been isolated from the affected swine population. The disease has been reported from at least 32 states of the United States and other countries, including Mexico, Peru, Dominican Republic, Canada, Columbia, Ecuador, and Ukraine, with repeated outbreaks in previously infected herds. Here we report the isolation and characterization of a novel mammalian orthoreovirus 3 (MRV3) from diarrheic feces of piglets from these outbreaks in three states and ring-dried swine blood meal from multiple sources. MRV3 could not be isolated from healthy or pigs that had recovered from epidemic diarrhea from four states. Several MRV3 isolates were obtained from chloroform-extracted pig feces or blood meal in cell cultures or developing chicken embryos. Biological characterization of two representative isolates revealed trypsin resistance and thermostability at 90°C. NextGen sequencing of ultrapurified viruses indicated a strong homology of the S1 segment to mammalian and bat MRV3. Neonatal piglets experimentally infected with these viruses or a chloroform extract of swine blood meal developed severe diarrhea and acute gastroenteritis with 100% mortality within 3 days postinfection. Therefore, the novel porcine MRV3 may contribute to enteric disease along with other swine enteric viruses. The role of MRV3 in the current outbreaks of porcine epidemic diarrhea in the United States remains to be determined, but the pathogenic nature of the virus warrants further investigations on its epidemiology and prevalence.

Phylogenetic Analysis of the Spike (S) Gene of the New Variants of Porcine Epidemic Diarrhoea Virus in Taiwan.

New variants of porcine epidemic diarrhoea virus (PEDV), which emerged in Taiwan in late 2013, have caused a high morbidity and mortality in neonatal piglets. To investigate the molecular characteristics of the spike (S) gene of the emerging Taiwan PEDV strains for a better understanding of the genetic diversity and relationship among the Taiwan new variants and the global PEDVs, full-length S genes of PEDVs from nine 1-7day-old piglets from three pig farms in the central and southern Taiwan were sequenced and analysed. The result of phylogenetic analysis of the S gene showed that all the Taiwan PEDV strains were closely related to the non-S INDEL strains from US, Canada and China, suggesting a common ancestor for these strains. As compared with the historic PEDVs and CV777-based vaccine strains, the nine Taiwan PEDV variants shared almost the same genetic signatures as the global non-S INDEL strains, including a series of insertions, deletions and mutations in the amino terminal as well as identical mutations in the neutralizing epitopes of the S gene. The high similarity of the S protein among the Taiwan and the globally emerged non-S INDEL PEDV strains suggests that the Taiwan new variants may share similar pathogenesis and immunogenicity as the global outbreak variants. The development of a novel vaccine based on the Taiwan or the global non-S INDEL strains may be contributive to the control of the current global porcine epidemic diarrhoea outbreaks.

Genetic characterization of porcine epidemic diarrhea virus in Korea from 1998 to 2013.

The number of porcine epidemic diarrhea (PED) cases has increased over the past 20 years in Korea, with a major outbreak in 2013. A total of 27 Korean strains from 1998 to 2013 were analyzed (excluding the noncoding regions) and divided into two groups for comparison of the spike (S), ORF3, envelope (E), membrane (M), and nucleocapsid (N) genes with those of reference strains, vaccine strains, and previously identified strains based on phylogenetic analysis. Analysis of the selection patterns of PEDV isolated in Korea indicated positive selection of nine nonsynonymous sites in the S and N proteins and negative selection at 97 sites for all of the proteins. Interestingly, eight nonsynonymous mutations in S showed no significant pattern change over the 15-year period, and one of eight mutation sites was found only in IC05TK, GN05DJ, and KNU0802 in the epidemic years 2005 and 2008. These eight mutations were also present during the epidemic years in China. Furthermore, of the signs of positive selection in the S protein, the conservative substitutions were more frequent than radical substitutions in PEDVs, suggesting that the evolution of Korean strains has been slow. Serological cross-reactivity was detected between three field PEDVs and two vaccine strains, with different serum neutralization titers. In conclusion, although Korean PEDVs have been evolving slowly, their diverse antigenicity and genetics imply that multilateral efforts to prevent future PED outbreaks are required.Electronic supplementary materialThe online version of this article (doi:10.1007/s00705-015-2353-y) contains supplementary material, which is available to authorized users.

Scientific Opinion on porcine epidemic diarrhoea and emerging porcine deltacoronavirus.

In the last decade, many porcine epidemic diarrhoea (PED) outbreaks have been reported by several countries in Asia whereas only a few Member States of the European Union (EU) have reported PED clinical cases and/or PED virus (PEDV)‐seropositive animals. This alphacoronavirus was first reported in the USA in May 2013, followed by rapid spread throughout the country and outbreaks reported by several countries in the Americas. The recent PEDV‐EU isolates have high level of sequence identity to PEDV‐Am isolates. Based on nucleotide sequencing, multiple variants of PEDV are circulating in Europe, the Americas and Asia but any difference in virulence and antigenicity is currently unknown. Serological cross‐reactivity has been reported between PEDV isolated in Europe and in the Americas; however no data regarding cross‐protection are available. The impact of different PEDV strains is difficult to compare between one country and another, since impact is dependent not only on pathogenicity but also on factors such as biosecurity, farm management, sanitary status or herd immune status. However, the clinical signs of PEDV infections in naive pigs are similar in different countries with mortalities up to 100% in naive newborn piglets. The impact of recently reported PED outbreaks in Asia and the USA seems to be more severe than what has been described in Europe. Infected animals, faeces, feed and objects contaminated with faeces are matrices that have been reported to transmit PEDV between farms. Infectious PEDV has been detected in spray‐dried porcine plasma (SDPP) in one study but the origin of the infectious PEDV in SDPP is not clear. Detection of porcine deltacoronavirus (PDCoV) has been reported in a few countries but only limited testing has been done. Based on the currently available information, it seems that PDCoV would have a lower impact than PEDV.

Reemergence of porcine epidemic diarrhea virus on Jeju Island

Abstract : Porcine epidemic diarrhea virus (PEDV) strains responsible for recent outbreaks in the United States havebeen occurring in Mainland Korea since late 2013. Over the past 10 years, PEDV outbreaks have not been reportedon Jeju Island. However, in late March of 2014, PEDV re-emerged on Jeju Island and was found to be geneticallyidentical to PEDV strains currently circulating in Mainland Korea. The present study was conducted to provide a betterunderstanding of the epidemiology of PEDV and more effective preventive measures against PED.Keywords : Jeju Island, Korea, porcine epidemic diarrhea virus, reemergence, US strain-like strains Porcine epidemic diarrhea (PED) is a devastating pig entericdisease causing lethal watery diarrhea followed by severedehydration with high mortality in neonatal piglets [10]. Thedisease was first recognized in England in 1971 [7], andsince then, outbreaks have been reported in Europe, Asia,and recently, North America including the United States [1,9, 13, 14]. The causative agent of this disease, the PED virus(PEDV), belongs to the Alphacoronavirus genus within thefamily Coronaviridae of the order Nidovirales [8, 10]. Thespike (S) protein of PEDV is the major virion envelopeglycoprotein; interacts with the host cellular receptor forvirus entry and mediates neutralizing antibodies. Therefore,the PEDV S protein is an appropriate viral gene forsequencing and molecular analyses to investigate the geneticrelatedness of PEDV isolates and the epidemiological statusof PEDV in the field [4].The first case of PED in Korea was confirmed in 1992 [3]and since its emergence, PED outbreaks have continuouslyoccurred every year, leading to a serious production loss tothe Korean pork industry up until early 2010. However, aftersevere outbreaks of foot-and-mouth disease (FMD) in 2010and 2011, the prevalence of PEDV infections in Korea wassignificantly reduced with only sporadic outbreaks. InNovember of 2013, PEDV suddenly recurred and subsequently,has swept rapidly across Mainland Korea. Genetic andphylogenetic analyses revealed that PEDV isolates responsiblefor the recurrence in Mainland Korea are most highly relatedto PEDV strains currently circulating in the United States [5].The last PEDV outbreak on Jeju Island was reported in 2004and since then, PEDV has not emerged again on Jeju Islandin almost 10 years. Beginning in late March of 2014, PEDVre-emerged in the Hanlim area of Jeju Island and subsequentlyspread to other districts, resulting in high mortality innewborn piglets. To determine the origin and diversity ofPEDV responsible for the ongoing outbreaks on Jeju Island,we sought to determine the full-length sequences of the Sproteins of field isolates identified from affected pig farms.From late March 2014 through early April 2014, 5 stoolspecimens were taken from sows and piglets with acute waterydiarrhea at different swine farms. Fecal samples were processedinto 10% suspensions as described previously [4] and initiallysubjected to RT-PCR using a TGE/PED Detection Kit(iNtRON Biotechnology, Korea) according to the manufac-turer’s protocol. The PEDV-positive supernatants were storedat

Characterization of the porcine epidemic diarrhea virus codon usage bias

Porcine epidemic diarrhea virus (PEDV) has been responsible for several recent outbreaks of porcine epidemic diarrhea (PED) and has caused great economic loss in the swine-raising industry. Considering the significance of PEDV, a systemic analysis was performed to study its codon usage patterns. The relative synonymous codon usage value of each codon revealed that codon usage bias exists and that PEDV tends to use codons that end in T. The mean ENC value of 47.91 indicates that the codon usage bias is low. However, we still wanted to identify the cause of this codon usage bias. A correlation analysis between the codon compositions (A3s, T3s, G3s, C3s, and GC3s), the ENC values, and the nucleotide contents (A%, T%, G%, C%, and GC%) indicated that mutational bias plays role in shaping the PEDV codon usage bias. This was further confirmed by a principal component analysis between the codon compositions and the axis values. Using the Gravy, Aroma, and CAI values, a role of natural selection in the PEDV codon usage pattern was also identified. Neutral analysis indicated that natural selection pressure plays a more important role than mutational bias in codon usage bias. Natural selection also plays an increasingly significant role during PEDV evolution. Additionally, gene function and geographic distribution also influence the codon usage bias to a degree.

Porcine coronavirus HKU15 detected in 9 US states, 2014.

Porcine coronavirus HKU15 detected in 9 US states, 2014.

Investigation into the role of potentially contaminated feed as a source of the first-detected outbreaks of porcine epidemic diarrhea in Canada.

SummaryIn January 2014, approximately 9 months following the initial detection of porcine epidemic diarrhea (PED) in the USA, the first case of PED was confirmed in a swine herd in south‐western Ontario. A follow‐up epidemiological investigation carried out on the initial and 10 subsequent Ontario PED cases pointed to feed as a common risk factor. As a result, several lots of feed and spray‐dried porcine plasma (SDPP) used as a feed supplement were tested for the presence of PEDV genome by real‐time RT‐PCR assay. Several of these tested positive, supporting the notion that contaminated feed may have been responsible for the introduction of PEDV into Canada. These findings led us to conduct a bioassay experiment in which three PEDV‐positive SDPP samples (from a single lot) and two PEDV‐positive feed samples supplemented with this SDPP were used to orally inoculate 3‐week‐old piglets. Although the feed‐inoculated piglets did not show any significant excretion of PEDV, the SDPP‐inoculated piglets shed PEDV at a relatively high level for ≥9 days. Despite the fact that the tested PEDV genome positive feed did not result in obvious piglet infection in our bioassay experiment, contaminated feed cannot be ruled out as a likely source of this introduction in the field where many other variables may play a contributing role.

Porcine epidemic diarrhea virus nucleocapsid protein antagonizes beta interferon production by sequestering the interaction between IRF3 and TBK1.

Porcine epidemic diarrhea virus (PEDV), a porcine enteropathogenic coronavirus, causes lethal watery diarrhea in piglets and results in large economic losses in many Asian and European countries. A large-scale outbreak of porcine epidemic diarrhea occurred in China in 2010, and the virus emerged in the United States in 2013 and spread rapidly, posing significant economic and public health concerns. Previous studies have shown that PEDV infection inhibits the synthesis of type I interferon (IFN), and viral papain-like protease 2 has been identified as an IFN antagonist. In this study, we found that the PEDV-encoded nucleocapsid (N) protein also inhibits Sendai virus-induced IFN-β production, IFN-stimulated gene expression, and activation of the transcription factors IFN regulatory factor 3 (IRF3) and NF-κB. We also found that N protein significantly impedes the activation of the IFN-β promoter stimulated by TBK1 or its upstream molecules (RIG-I, MDA5, IPS-1, and TRAF3) but does not counteract its activation by IRF3. A detailed analysis revealed that the PEDV N protein targets TBK1 by direct interaction and that this binding sequesters the association between TBK1 and IRF3, which in turn inhibits both IRF3 activation and type I IFN production. Together, our findings demonstrate a new mechanism evolved by PEDV to circumvent the host's antiviral immunity. PEDV has received increasing attention since the emergence of a PEDV variant in China and the United States. Here, we identify nucleocapsid (N) protein as a novel PEDV-encoded interferon (IFN) antagonist and demonstrate that N protein antagonizes IFN production by sequestering the interaction between IRF3 and TBK1, a critical step in type I IFN signaling. This adds another layer of complexity to the immune evasion strategies evolved by this economically important viral pathogen. An understanding of its immune evasion mechanism may direct us to novel therapeutic targets and more effective vaccines against PEDV infection.