Genetic characterization and phylogenetic analysis of porcine deltacoronavirus (PDCoV) in Shandong Province, China

Cell-surface d-glucuronyl C5-epimerase binds to porcine deltacoronavirus spike protein facilitating viral entry

Porcine deltacoronavirus (PDCoV) is an emerging swine enteric coronavirus with zoonotic potential. The coronavirus spike (S) glycoprotein, especially the S1 subunit, mediates viral entry by binding to cellular receptors. However, the functional receptor of PDCoV remains poorly understood. In this study, we used the soluble PDCoV S1 protein as bait to capture the S1-binding cellular transmembrane proteins in combined immunoprecipitation and mass spectrometry analyses. A single guide RNA screen identified d-glucuronyl C5-epimerase (GLCE), a heparan sulfate-modifying enzyme, as a proviral host factor for PDCoV infection. GLCE knockout significantly inhibited the attachment and internalization stages of PDCoV infection. We also demonstrated the interaction between GLCE and PDCoV S with coimmunoprecipitation in both an overexpression system and PDCoV-infected cells. GLCE could be localized to the cell membrane, and an anti-GLCE antibody suppressed PDCoV infection. Although GLCE expression alone did not render nonpermissive cells susceptible to PDCoV infection, GLCE promoted the binding of PDCoV S to porcine amino peptidase N (pAPN), acting synergistically with pAPN to enhance PDCoV infection. In conclusion, our results demonstrate that GLCE is a novel cell-surface factor facilitating PDCoV entry and provide new insights into PDCoV infection.

IMPORTANCE

The identification of viral receptors is of great significance, potentially extending our understanding of viral infection and pathogenesis. Porcine deltacoronavirus (PDCoV) is an emerging enteropathogenic coronavirus with the potential for cross-species transmission. However, the receptors or coreceptors of PDCoV are still poorly understood. The present study confirms that d-glucuronyl C5-epimerase (GLCE) is a positive regulator of PDCoV infection, promoting viral attachment and internalization. The anti-GLCE antibody suppressed PDCoV infection. Mechanically, GLCE interacts with PDCoV S and promotes the binding of PDCoV S to porcine amino peptidase N (pAPN), acting synergistically with pAPN to enhance PDCoV infection. This work identifies GLCE as a novel cell-surface factor facilitating PDCoV entry and paves the way for further insights into the mechanisms of PDCoV infection.

Pyrococcus furiosus Argonaute Based Detection Assays for Porcine Deltacoronavirus

Porcine deltacoronavirus (PDCoV) is a major cause of diarrhea and diarrhea-related deaths among piglets and results in massive losses to the overall porcine industry. The clinical manifestations of porcine diarrhea brought on by the porcine epidemic diarrhea virus (PEDV), porcine transmissible gastroenteritis virus (TGEV), and PDCoV are oddly similar to each other. Hence, the identification of different pathogens through molecular diagnosis and serological techniques is crucial. Three novel detection methods for identifying PDCoV have been developed utilizing recombinase-aided amplification (RAA) or reverse transcription recombinase-aided amplification (RT-RAA) in conjunction with Pyrococcus furiosus Argonaute (PfAgo): RAA-PfAgo, one-pot RT-RAA-PfAgo, and one-pot RT-RAA-PfAgo-LFD. The indicated approaches have a detection limit of around 60 copies/μL of PDCoV and do not cross-react with other viruses including PEDV, TGEV, RVA, PRV, PCV2, or PCV3. The applicability of one-pot RT-RAA-PfAgo and one-pot RT-RAA-PfAgo-LFD were examined using clinical samples and showed a positive rate comparable to the qPCR method. These techniques offer cutting-edge technical assistance for identifying, stopping, and managing PDCoV.

Porcine deltacoronavirus nsp5 antagonizes type I interferon signaling by cleaving IFIT3

Porcine deltacoronavirus (PDCoV) has caused enormous economic losses to the global pig industry. However, the immune escape mechanism of PDCoV remains to be fully clarified. Transcriptomic analysis revealed a high abundance of interferon (IFN)-induced protein with tetratricopeptide repeats 3 (IFIT3) transcripts after PDCoV infection, which initially implied a correlation between IFIT3 and PDCoV. Further studies showed that PDCoV nsp5 could antagonize the host type I interferon signaling pathway by cleaving IFIT3. We demonstrated that PDCoV nsp5 cleaved porcine IFIT3 (pIFIT3) at Gln-406. Similar cleavage of endogenous IFIT3 has also been observed in PDCoV-infected cells. The pIFIT3-Q406A mutant was resistant to nsp5-mediated cleavage and exhibited a greater ability to inhibit PDCoV infection than wild-type pIFIT3. Furthermore, we found that cleavage of IFIT3 is a common characteristic of nsp5 proteins of human coronaviruses, albeit not alphacoronavirus. This finding suggests that the cleavage of IFIT3 is an important mechanism by which PDCoV nsp5 antagonizes IFN signaling. Our study provides new insights into the mechanisms by which PDCoV antagonizes the host innate immune response.IMPORTANCEPorcine deltacoronavirus (PDCoV) is a potential emerging zoonotic pathogen, and studies on the prevalence and pathogenesis of PDCoV are ongoing. The main protease (nsp5) of PDCoV provides an excellent target for antivirals due to its essential and conserved function in the viral replication cycle. Previous studies have revealed that nsp5 of PDCoV antagonizes type I interferon (IFN) production by targeting the interferon-stimulated genes. Here, we provide the first demonstration that nsp5 of PDCoV antagonizes IFN signaling by cleaving IFIT3, which affects the IFN response after PDCoV infection. Our findings reveal that PDCoV nsp5 is an important interferon antagonist and enhance the understanding of immune evasion by deltacoronaviruses.

Genetic and Evolutionary Analysis of Porcine Deltacoronavirus in Guangxi Province, Southern China, from 2020 to 2023

Porcine deltacoronavirus (PDCoV) has shown large-scale global spread since its discovery in Hong Kong in 2012. In this study, a total of 4897 diarrheal fecal samples were collected from the Guangxi province of China from 2020 to 2023 and tested using RT-qPCR. In total, 362 (362/4897, 7.39%) of samples were positive for PDCoV. The S, M, and N gene sequences were obtained from 34 positive samples after amplification and sequencing. These PDCoV gene sequences, together with other PDCoV S gene reference sequences from China and other countries, were analyzed. Phylogenetic analysis revealed that the Chinese PDCoV strains have diverged in recent years. Bayesian analysis revealed that the new China 1.3 lineage began to diverge in 2012. Comparing the amino acids of the China 1.3 lineage with those of other lineages, the China 1.3 lineage showed variations of mutations, deletions, and insertions, and some variations demonstrated the same as or similar to those of the China 1.2 lineage. In addition, recombination analysis revealed interlineage recombination in CHGX-MT505459-2019 and CHGX-MT505449-2017 strains from Guangxi province. In summary, the results provide new information on the prevalence and evolution of PDCoV in Guangxi province in southern China, which will facilitate better comprehension and prevention of PDCoV.

Development of an RT-PCR-based RspCas13d system to detect porcine deltacoronavirus

Porcine deltacoronavirus (PDCoV) is an enteropathogen that causes diarrhea in piglets and may undergo cross-species transmission. The prevention and control of PDCoV are complicated, and a sensitive, specific, and accessible method of diagnosis would be advantageous. Whereas qPCR is a standard approach for detecting PDCoV, it is not effectively sensitive. In the present study, we report such a strategy using an RT-PCR-based RspCas13d detection system and its efficacy in clinical sample diagnosis. The detection limit of this method was 4 copies/μL and no cross-reaction with other viruses such as the porcine epidemic diarrhea virus, classical swine fever virus, pseudorabies virus, porcine reproductive and respiratory syndrome virus, transmissible gastroenteritis virus and porcine rotavirus. The method was also effective in clinical samples. In summary, we demonstrate that RT-PCR-based RspCas13d detection system is an extremely sensitive and specific nucleic acid-based approach for detecting PDCoV. KEY POINTS: • RspCas13d can be used as a candidate molecular diagnostic tool to diagnose viral genomes. • A novel method is proposed using an RT-PCR-based RspCas13d detection system and its effectiveness in the detection of PDCoV. • The RT-PCR-based RspCas13d detection system has excellent sensitivity and specificity.

Modified diffusive epidemic process on Apollonian networks

We present an analysis of an epidemic spreading process on an Apollonian network that can describe an epidemic spreading in a non-sedentary population. We studied the modified diffusive epidemic process using the Monte Carlo method by computational analysis. Our model may be helpful for modeling systems closer to reality consisting of two classes of individuals: susceptible (A) and infected (B). The individuals can diffuse in a network according to constant diffusion rates [Formula: see text] and [Formula: see text], for the classes A and B, respectively, and obeying three diffusive regimes, i.e., [Formula: see text], [Formula: see text], and [Formula: see text]. Into the same site i, the reaction occurs according to the dynamical rule based on Gillespie's algorithm. Finite-size scaling analysis has shown that our model exhibits continuous phase transition to an absorbing state with a set of critical exponents given by [Formula: see text], [Formula: see text], and [Formula: see text] familiar to every investigated regime. In summary, the continuous phase transition, characterized by this set of critical exponents, does not have the same exponents of the mean-field universality class in both regular lattices and complex networks.

Evolutionary plasticity of zoonotic porcine Deltacoronavirus (PDCoV): genetic characteristics and geographic distribution

The emergence and rapid spread of the acute respiratory syndrome coronavirus-2 have confirmed that animal coronaviruses represent a potential zoonotic source. Porcine deltacoronavirus is a worldwide evolving enteropathogen of swine, detected first in Hong Kong, China, before its global identification. Following the recent detection of PDCoV in humans, we attempted in this report to re-examine the status of PDCoV phylogenetic classification and evolutionary characteristics. A dataset of 166 complete PDCoV genomes was analyzed using the Maximum Likelihood method in IQ-TREE with the best-fitting model GTR + F + I + G4, revealing two major genogroups (GI and GII), with further seven and two sub-genogroups, (GI a-g) and (GII a-b), respectively. PDCoV strains collected in China exhibited the broadest genetic diversity, distributed in all subgenotypes. Thirty-one potential natural recombination events were identified, 19 of which occurred between China strains, and seven involved at least one China strain as a parental sequence. Importantly, we identified a human Haiti PDCoV strain as recombinant, alarming a possible future spillover that could become a critical threat to human health. The similarity and recombination analysis showed that PDCoV spike ORF is highly variable compared to ORFs encoding other structural proteins. Prediction of linear B cell epitopes of the spike glycoprotein and the 3D structural mapping of amino acid variations of two representative strains of GI and GII showed that the receptor-binding domain (RBD) of spike glycoprotein underwent a significant antigenic drift, suggesting its contribution in the genetic diversity and the wider spread of PDCoV.

The recombinant pseudorabies virus expressing porcine deltacoronavirus spike protein is safe and effective for mice

BACKGROUND

Porcine deltacoronavirus (PDCoV) is a new pathogenic porcine intestinal coronavirus, which has appeared in many countries since 2012. PDCoV disease caused acute diarrhea, vomiting, dehydration and death in piglets, resulted in significant economic loss to the pig industry. However, there is no commercially available vaccine for PDCoV. In this study, we constructed recombinant pseudorabies virus (rPRVXJ-delgE/gI/TK-S) expressing PDCoV spike (S) protein and evaluated its safety and immunogenicity in mice.

RESULTS

The recombinant strain rPRVXJ-delgE/gI/TK-S obtained by CRISPR/Cas gE gene editing technology and homologous recombination technology has genetic stability in baby hamster syrian kidney-21 (BHK-21) cells and is safe to mice. After immunizing mice with rPRVXJ-delgE/gI/TK-S, the expression levels of IFN-γ and IL-4 in peripheral blood of mice were up-regulated, the proliferation of spleen-specific T lymphocytes and the percentage of CD4⁺ and CD8⁺ lymphocytes in mice spleen was increased. rPRVXJ-delgE/gI/TK-S showed good immunogenicity for mice. On the seventh day after booster immunity, PRV gB and PDCoV S specific antibodies were detected in mice, and the antibody level continued to increase, and the neutralizing antibody level reached the maximum at 28 days post- immunization (dpi). The recombinant strain can protect mice with 100% from the challenge of virulent strain (PRV XJ) and accelerate the detoxification of PDCoV in mice.

CONCLUSION

The recombinant rPRVXJ-delgE/gI/TK-S strain is safe and effective with strong immunogenicity and is expected to be a candidate vaccine against PDCoV and PRV.

Genetic Characteristics and Pathogenicity of a Novel Porcine Deltacoronavirus Southeast Asia-Like Strain Found in China

Farmers involved in the lucrative pork trading business between China and Southeast Asian countries should be aware of a recently discovered novel porcine deltacoronavirus (PDCoV) in Guangxi province, China. A PDCoV strain, CHN/GX/1468B/2017, was isolated from the small intestinal contents of piglets with diarrhea from this region, with a titer of 1 × 10^8.0 TCID₅₀/mL on LLC-PK cells. The full-length genome sequence consists of 25,399 nt as determined by next-generation sequencing and this was deposited in the GenBank (accession number MN025260.1). Genomic analysis showed that CHN/GX/1468B/2017 strain had 96.9~99.4% nucleotide homology with other 87 referenced PDCoV strains from different areas, and contained 6 and 9-nt deletions at positions 1,733~1,738 and 2,804~2,812, respectively, in the ORF1a gene. Phylogenetic analyses based on the whole gene sequence as well as S protein and ORF1a/1b protein sequences all showed that this strain was closely related to the Southeast Asia strain. When 7-day-old piglets were inoculated orally with the CHN/GX/1468B/2017 strain, they developed severe diarrhea, with a peak of fecal viral shedding at 4 days post-infection. Although no death or fever were observed, the CHN/GX/1468B/2017 strain produced a wide range of tissue tropism, with the main target being the intestine. Importantly, the VH:CD ratios of the jejunum and ileum in infected piglets were significantly lower than controls. These results indicate that CHN/GX/1468B/2017, isolated in China, is a novel PDCoV Southeast Asia-like strain with distinct genetic characteristics and pathogenicity. This finding enriches the international information on the genetic diversity of PDCoV.

Phylogenetic Classification of Global Porcine Deltacoronavirus (PDCoV) Reference Strains and Molecular Characterization of PDCoV in Taiwan

Porcine deltacoronavirus (PDCoV), a highly transmissible intestinal pathogen, causes mild to severe clinical symptoms, such as anorexia, vomiting and watery diarrhea, in piglets and/or sows. Since the first report of PDCoV infection in Hong Kong in 2012, the virus has readily disseminated to North America and several countries in Asia. However, to date, no unified phylogenetic classification system has been developed. To fill this gap, we classified historical PDCoV reference strains into two major genogroups (G-I and G-II) and three subgroups (G-II-a, G-II-b and G-II-c). In addition, no genetic research on the whole PDCoV genome or spike gene has been conducted on isolates from Taiwan so far. To delineate the genetic characteristics of Taiwanese PDCoV, we performed whole-genome sequencing to decode the viral sequence. The PDCoV/104-553/TW-2015 strain is closely related to the G-II-b group, which is mainly composed of PDCoV variants from China. Additionally, various mutations in the Taiwanese PDCoV (104-553/TW-2015) strain might be linked to the probability of recombination with other genogroups of PDCoVs or other porcine coronaviruses. These results represent a pioneering phylogenetic characterization of the whole genome of a PDCoV strain isolated in Taiwan in 2015 and will potentially facilitate the development of applicable preventive strategies against this problematic virus.

Emergence of porcine circovirus-like viruses associated with porcine diarrheal disease in China

Background

The circular replication‐associated protein (Rep)‐encoding single‐stranded (CRESS) DNA virus emergence in diverse host has been associated with severe disease. Porcine circovirus‐like virus (Po‐Circo‐like [PCL] virus) is a CRESS DNA virus, the prevalence and pathogenicity of which are rarely studied.

Methods

We obtained two blood samples, four faecal samples, and two intestinal samples from a pig farm suffered from diarrheal disease in the delivery room in September 2020 and attempted to isolate and identify a causative pathogen. Subsequently, only PCL virus was positive, and qRT‐PCR was designed to detect the loading titre of PCL virus. We then initiated a heightened surveillance program on the pathogenicity and epidemiology of PCL virus.

Results

Six PCL virus strains, with severe diarrhoea and haemorrhagic enteritis, have been found in six different pig farms in Guangdong province, China. A multiple sequence alignment of these PCL viruses and bovine circovirus‐like virus/CH showed a similarity of 92.5‐94.8% for the Rep protein, indicating these PCL viruses are highly homologous to Bo‐Circo‐like virus associated with calf diarrhoea. There were striking similarities between the PCL virus and bovine circovirus‐like virus outbreaks in aetiological settings and Genomic sequence. We found that 11.2% (20/178) of diarrhoea samples and 13.3% (6/45) of pig farms were positive for PCL virus, suggesting that PCL virus may have spread widely in Pig farms. Moreover, this article underscores the risk of PCL virus spilling over and adapting to new species.

Conclusions

Porcine circovirus‐like virus was found to be associated with porcine diarrheal disease in China.

Genetic characterization and phylogenetic analysis of porcine epidemic diarrhea virus in Guangdong, China, between 2018 and 2019

Porcine epidemic diarrhea virus (PEDV), a leading cause of piglet diarrhea outbreaks, poses a significant danger to the swine industry. The aim of this study was to investigate the epidemic characteristics of PEDV that was circulating in Guangdong province, one of China's major pig producing provinces. Clinical samples were collected from eight pig farms in Guangdong province between 2018 and 2019 and tested for the major porcine enteric pathogens, including PEDV, transmissible gastroenteritis virus (TGEV), Swine enteric coronavirus (SeCoV), Swine acute diarrhea syndrome coronavirus (SADS-CoV), porcine deltacoronavirus (PDCoV), and porcine rotavirus (RV). As a result, only PEDV and RV were detected at a rate of 47.0% (16/34) and 18.6% (8/34), respectively. Coinfectoin with PEDV and RV occurred at a rate of PEDV 12.5% (2/16). Subsequently, the full-length S gene sequences of 13 PEDV strains were obtained, and phylogenetic analysis suggested the presence of GII-c group PEDV strains in this region (non-S-INDEL). Two novel common amino acid insertions (55T/IG56 and 551L) and one novel glycosylation site (1199G+) were detected when the CV777 and ZJ08 vaccine strains were compared. Furthermore, intragroup recombination events in the S gene regions 51-548 and 2478-4208 were observed in the PEDV strains studied. In summary, the observations provide current information on the incidence of viral agents causing swine diarrhea in southern China and detailed the genetic characteristics and evolutionary history of the dominant PEDV field strains. Our findings will aid in the development of an updated vaccine for the prevention and control of PEDV variant strains.

Attenuation of porcine deltacoronavirus disease severity by porcine reproductive and respiratory syndrome virus coinfection in a weaning pig model

Porcine deltacoronavirus (PDCoV) is a potentially emerging zoonotic pathogen that causes severe diarrhea in young pigs, with a risk of fatal dehydration. Its pathogenicity on neonatal piglet has been previously reported, however, it is less known if the coinfection with immunosuppressive pathogens can influence PDCoV disease manifestation. Here, a coinfection model of PDCoV and porcine reproductive and respiratory syndrome virus (PRRSV), a global-spread immunosuppressive virus, was set to study their interaction. Weaning pigs in the coinfection group were intranasally inoculated with PRRSV NADC30-like virus and latterly orally inoculated with PDCoV at three day-post-inoculation (DPI). Unexpectedly, compared with pigs in the PDCoV single-infected group, the coinfected pigs did not show any obvious diarrhea, as PDCoV fecal shedding, average daily weight gain (ADWG), gross and microscopic lesions and PDCoV IHC scores consistently indicated that PRRSV coinfection lessened PDCoV caused diarrhea. Additionally, three proinflammatory cytokines TNF-α, IL-1 and IL-6, which can be secreted by PRRSV infected macrophages, were detected to be highly expressed at the intestine from both PRRSV infected groups. By adding to PDCoV-infected cells, these three cytokines were further confirmed to be able to inhibit the PDCoV replication post its cellular entry. Meanwhile, the inhibition effect of the supernatant from PRRSV-infected PAMs could be obviously blocked by the antagonist of these three cytokines. In conclusion, PRRSV coinfection increased TNF-α, IL-1, and IL-6 in the microenvironment of intestines, which inhibits the PDCoV proliferation, leading to lessened severity of diarrhea. The findings provide some new insight into the pathogenesis and replication regulation of PDCoV.

Coronaviruses in farm animals: Epidemiology and public health implications

Coronaviruses (CoVs) are documented in a wide range of animal species, including terrestrial and aquatic, domestic and wild. The geographic distribution of animal CoVs is worldwide and prevalences were reported in several countries across the five continents. The viruses are known to cause mainly gastrointestinal and respiratory diseases with different severity levels. In certain cases, CoV infections are responsible of huge economic losses associated or not to highly public health impact. Despite being enveloped, CoVs are relatively resistant pathogens in the environment. Coronaviruses are characterized by a high mutation and recombination rate, which makes host jumping and cross-species transmission easy. In fact, increasing contact between different animal species fosters cross-species transmission, while agriculture intensification, animal trade and herd management are key drivers at the human-animal interface. If contacts with wild animals are still limited, humans have much more contact with farm animals, during breeding, transport, slaughter and food process, making CoVs a persistent threat to both humans and animals. A global network should be established for the surveillance and monitoring of animal CoVs.

A comprehensive review of SARS-CoV-2 genetic mutations and lessons from animal coronavirus recombination in one health perspective

SARS-CoV-2 was originated from zoonotic coronaviruses and confirmed as a novel beta-coronavirus, which causes serious respiratory illness such as pneumonia and lung failure, COVID-19. In this review, we describe the genetic characteristics of SARS-CoV-2, including types of mutation, and molecular epidemiology, highlighting its key difference from animal coronaviruses. We further summarized the current knowledge on clinical, genetic, and pathological features of several animal coronaviruses and compared them with SARS-CoV-2, as well as recent evidences of interspecies transmission and recombination of animal coronaviruses to provide a better understanding of SARS-CoV-2 infection in One Health perspectives. We also discuss the potential wildlife hosts and zoonotic origin of this emerging virus in detail, that may help mitigate the spread and damages caused by the disease.

Emergence of Thailand-like strains of porcine deltacoronavirus in Guangxi Province, China

Porcine deltacoronavirus (PDCoV) has been detected sporadically in China since its first description in 2012. In our study, 62 faecal and intestinal samples from pigs with diarrhoea were collected in Guangxi Province, China, during 2017 and 2018. Twelve samples (19.4%, 12/62) were positive for PDCoV. Five complete genomes of PDCoV were then determined, and sequence alignment revealed that the five strains had discontinuous deletions at 400–401 aa in non‐structural protein 2 (NSP2) and 758–760 aa in non‐structural protein 3 (NSP3) compared with the respective proteins in the HKU15‐44 strain. Notably, the CHN‐GX81‐2018 strain contained two insertions in the S gene and 3′‐UTR. Multiple sequence alignment and phylogenetic analysis showed that four strains shared 98.2%–98.4% nucleotide identity with CHN‐AH‐2004 and were classified into a new cluster of China lineage strains, whereas the CHN‐GX81‐2018 strain shared 98.7% nucleotide identity with Vietnam/Binh21/2015 and belonged to the Vietnam/Laos/Thailand lineage. Recombination analyses revealed that four strains were the result of recombination between CHN‐HB‐2014 and Vietnam/Binh21/2015 strains. This study demonstrated the co‐existence of multiple lineages of PDCoV in China, and our findings will aid the reorganization and evolution of the virus.

Characterization, pathogenicity and protective efficacy of a cell culture-derived porcine deltacoronavirus

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A PDCoV strain, CH/XJYN/2016, was successfully isolated and its biological characteristics were determined.

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Pathogenicity of CH/XJYN/2016 in suckling piglets and conventional weaned pigs were determined.

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An inactivated cell-adapted CH/XJYN/2016-based vaccine candidate was developed and its efficacy was evaluated.

Porcine deltacoronavirus (PDCoV) is a novel swine enteropathogenic coronavirus that causes acute diarrhea, vomiting, dehydration and mortality in neonatal piglets, resulting in significant economic losses to the pig industry. However, there is currently little information on vaccine studies and commercially available vaccines for PDCoV. Hence, herein, a PDCoV strain, CH/XJYN/2016, was successfully isolated and serially propagated in vitro, and its biological characteristics were determined. Compared to that of previously reported and recently isolated PDCoV strains from China and the United States, the S gene of the CH/XJYN/2016 strain contains novel mutations. Infection studies revealed that CH/XJYN/2016 is pathogenic to suckling piglets and conventional weaned pigs. In addition, the median pig diarrhea dose (PDD₅₀) of PDCoV in conventional weaned pigs was determined (2.0 log₁₀PDD₅₀/3 mL). Furthermore, an inactivated cell-adapted CH/XJYN/2016-based vaccine candidate was developed with different adjuvants. Compared with nonvaccinated pigs, conventional weaned pigs given the inactivated vaccine developed a potent humoral immune response and showed no clinical signs or viral shedding after challenge, indicating a potent protective effect of the vaccine against PDCoV infection. Therefore, the PDCoV vaccine developed in this study is a promising vaccine candidate that can be used for the control of PDCoV infection in pigs.