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Porcine Health Management Mar 2024Diarrheal diseases caused by viral agents have led to a great morbidity, mortality, and economic loss in global pig industry. Porcine epidemic diarrhea virus (PEDV),...
BACKGROUND
Diarrheal diseases caused by viral agents have led to a great morbidity, mortality, and economic loss in global pig industry. Porcine epidemic diarrhea virus (PEDV), transmissible gastroenteritis virus (TGEV), porcine deltacoronavirus (PDCoV), and group A porcine rotavirus (RVA) are main causative agents of swine viral diarrhea with similar clinical signs on Chinese farms and their co-infection is also common. However, it is still lack of a convenient method to detect these four agents.
METHODS
A TaqMan multiplex qPCR method was developed to detect PEDV, TGEV, PDCoV, and RVA, simultaneously. This method was then applied to investigate 7,342 swine fecal samples or rectal swabs, as well as 1,246 swine intestinal samples collected from 2075 farms in China in 2022.
RESULTS
Minimum detection limits of this method were 3 copies/µL for PEDV, 4 copies/µL for TGEV, 8 copies/µL for RVA, and 8 copies/µL for PDCoV, suggesting a good sensitivity. No signals were observed by using this method detecting other viral agents commonly prevalent in pigs, which is suggestive of a good specificity. Application of this method on investigating clinical samples demonstrated a relatively high positive rate for PEDV (22.21%, 1907/8588) and RVA (44.00%, 3779/8588). In addition, co-infection between PEDV and RVA was observed on 360 investigated farms, accounting for 17.35% (360/2075) of the farms where co-infection events were screened.
CONCLUSIONS
A TaqMan multiplex qPCR method targeting PEDV, TGEV, PDCoV, and RVA was developed in this study. This method demonstrated a good specificity and sensitivity on investigating these four common viruses responsible for viral diarrhea on Chinese pig farms, which represents a convenient method for the monitoring and differential diagnosis of swine viral diarrhea.
PubMed: 38444040
DOI: 10.1186/s40813-024-00364-y -
Journal of Virology Mar 2024Continuously emerging highly pathogenic coronaviruses remain a major threat to human and animal health. Porcine deltacoronavirus (PDCoV) is a newly emerging enterotropic...
Continuously emerging highly pathogenic coronaviruses remain a major threat to human and animal health. Porcine deltacoronavirus (PDCoV) is a newly emerging enterotropic swine coronavirus that causes large-scale outbreaks of severe diarrhea disease in piglets. Unlike other porcine coronaviruses, PDCoV has a wide range of species tissue tropism, including primary human cells, which poses a significant risk of cross-species transmission. Nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain-containing 1 (NLRP1) has a key role in linking host innate immunity to microbes and the regulation of inflammatory pathways. We now report a role for NLRP1 in the control of PDCoV infection. Overexpression of NLRP1 remarkably suppressed PDCoV infection, whereas knockout of NLRP1 led to a significant increase in PDCoV replication. A mechanistic study revealed that NLRP1 suppressed PDCoV replication in cells by upregulating IL-11 expression, which in turn inhibited the phosphorylation of the ERK signaling pathway. Furthermore, the ERK phosphorylation inhibitor U0126 effectively hindered PDCoV replication in pigs. Together, our results demonstrated that NLRP1 exerted an anti-PDCoV effect by IL-11-mediated inhibition of the phosphorylation of the ERK signaling pathway, providing a novel antiviral signal axis of NLRP1-IL-11-ERK. This study expands our understanding of the regulatory network of NLRP1 in the host defense against virus infection and provides a new insight into the treatment of coronaviruses and the development of corresponding drugs.IMPORTANCECoronavirus, which mainly infects gastrointestinal and respiratory epithelial cells , poses a huge threat to both humans and animals. Although porcine deltacoronavirus (PDCoV) is known to primarily cause fatal diarrhea in piglets, reports detected in plasma samples from Haitian children emphasize the potential risk of animal-to-human spillover. Finding effective therapeutics against coronaviruses is crucial for controlling viral infection. Nucleotide-binding oligomerization-like receptor (NLR) family pyrin domain-containing 1 (NLRP1), a key regulatory factor in the innate immune system, is highly expressed in epithelial cells and associated with the pathogenesis of viruses. We demonstrate here that NLRP1 inhibits the infection of the intestinal coronavirus PDCoV through IL-11-mediated phosphorylation inhibition of the ERK signaling pathway. Furthermore, the ERK phosphorylation inhibitor can control the infection of PDCoV in pigs. Our study emphasizes the importance of NLRP1 as an immune regulatory factor and may open up new avenues for the treatment of coronavirus infection.
Topics: Animals; Child; Humans; Coronavirus Infections; Deltacoronavirus; Diarrhea; Haiti; Interleukin-11; NLR Proteins; Nucleotides; Phosphorylation; Signal Transduction; Swine; Swine Diseases; Zoonoses
PubMed: 38411106
DOI: 10.1128/jvi.01982-23 -
Microorganisms Feb 2024Porcine 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...
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.
PubMed: 38399820
DOI: 10.3390/microorganisms12020416 -
Pathogens (Basel, Switzerland) Feb 2024Swine enteric coronaviruses (SECoVs), including porcine deltacoronavirus (PDCoV), transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), and...
Swine enteric coronaviruses (SECoVs), including porcine deltacoronavirus (PDCoV), transmissible gastroenteritis virus (TGEV), porcine epidemic diarrhea virus (PEDV), and swine acute diarrhea syndrome coronavirus (SADS-CoV), have caused high mortality in piglets and, therefore, pose serious threats to the pork industry. Coronaviruses exhibit a trend of interspecies transmission, and understanding the host range of SECoVs is crucial for improving our ability to predict and control future epidemics. Here, the replication of PDCoV, TGEV, and PEDV in cells from different host species was compared by measuring viral genomic RNA transcription and protein synthesis. We demonstrated that PDCoV had a higher efficiency in infecting human lung adenocarcinoma cells (A549), Madin-Darby bovine kidney cells (MDBK), Madin-Darby canine kidney cells (MDCK), and chicken embryonic fibroblast cells (DF-1) than PEDV and TGEV. Moreover, trypsin can enhance the infectivity of PDCoV to MDCK cells that are nonsusceptible to TGEV. Additionally, structural analyses of the receptor ectodomain indicate that PDCoV S1 engages Aminopeptidase N (APN) via domain II, which is highly conserved among animal species of different vertebrates. Our findings provide a basis for understanding the interspecies transmission potential of these three porcine coronaviruses.
PubMed: 38392912
DOI: 10.3390/pathogens13020174 -
Journal of Virology Mar 2024The microtubule (MT) is a highly dynamic polymer that functions in various cellular processes through MT hyperacetylation. Thus, many viruses have evolved mechanisms to...
The microtubule (MT) is a highly dynamic polymer that functions in various cellular processes through MT hyperacetylation. Thus, many viruses have evolved mechanisms to hijack the MT network of the cytoskeleton to allow intracellular replication of viral genomic material. Coronavirus non-structural protein 8 (nsp8), a component of the viral replication transcriptional complex, is essential for viral survival. Here, we found that nsp8 of porcine deltacoronavirus (PDCoV), an emerging enteropathogenic coronavirus with a zoonotic potential, inhibits interferon (IFN)-β production by targeting melanoma differentiation gene 5 (MDA5), the main pattern recognition receptor for coronaviruses in the cytoplasm. Mechanistically, PDCoV nsp8 interacted with MDA5 and induced autophagy to degrade MDA5 in wild-type cells, but not in autophagy-related (ATG)5 or ATG7 knockout cells. Further screening for autophagic degradation receptors revealed that nsp8 interacts with sequestosome 1/p62 and promotes p62-mediated selective autophagy to degrade MDA5. Importantly, PDCoV nsp8 induced hyperacetylation of MTs, which in turn triggered selective autophagic degradation of MDA5 and subsequent inhibition of IFN-β production. Overall, our study uncovers a novel mechanism employed by PDCoV nsp8 to evade host innate immune defenses. These findings offer new insights into the interplay among viruses, IFNs, and MTs, providing a promising target to develop anti-viral drugs against PDCoV.IMPORTANCECoronavirus nsp8, a component of the viral replication transcriptional complex, is well conserved and plays a crucial role in viral replication. Exploration of the role mechanism of nsp8 is conducive to the understanding of viral pathogenesis and development of anti-viral strategies against coronavirus. Here, we found that nsp8 of PDCoV, an emerging enteropathogenic coronavirus with a zoonotic potential, is an interferon antagonist. Further studies showed that PDCoV nsp8 interacted with MDA5 and sequestosome 1/p62, promoting p62-mediated selective autophagy to degrade MDA5. We further found that PDCoV nsp8 could induce hyperacetylation of MT, therefore triggering selective autophagic degradation of MDA5 and inhibiting IFN-β production. These findings reveal a novel immune evasion strategy used by PDCoV nsp8 and provide insights into potential therapeutic interventions.
Topics: Animals; Autophagy; Coronavirus Infections; Deltacoronavirus; Interferons; Microtubules; Sequestosome-1 Protein; Swine; Swine Diseases
PubMed: 38353538
DOI: 10.1128/jvi.00003-24 -
MSystems Mar 2024Porcine deltacoronavirus (PDCoV) is an enteropathogenic coronavirus that mainly causes diarrhea in suckling piglets, and also has the potential for cross-species...
Porcine deltacoronavirus (PDCoV) is an enteropathogenic coronavirus that mainly causes diarrhea in suckling piglets, and also has the potential for cross-species transmission. However, there are still no commercial vaccines available to prevent and control PDCoV infection. In this study, PDCoV strain HNZK-02 was serially propagated for up to 150 passages and the amino acid changes have mainly occurred in the S protein during serial passage which caused structure change. PDCoV HNZK-02-passage 5 (P5)-infected piglets exhibited acute and severe watery diarrhea, an obvious intestinal damage, while the piglets infected with PDCoV HNZK-02-P150 showed no obvious clinical signs, weak intestinal lesions, and lower viral loads in rectal swabs and various tissues. Compared with the PDCoV HNZK-02-P5 infection, HNZK-02-P150 infection resulted in a decrease in intestinal mucosal permeability and pro-inflammatory cytokines. Moreover, PDCoV HNZK-02-P5 infection had significantly reduced bacterial diversity and increased relative abundance of opportunistic pathogens, while PDCoV HNZK-02-P150 infection did not significantly affect the bacterial diversity, and the relative abundance of probiotics increased. Furthermore, the alterations of gut microbiota were closely related to the change of pro-inflammatory factor. Metagenomics prediction analysis demonstrated that HNZK-02-P150 modulated the tyrosine metabolism, Nucleotide-binding and oligomerization domain (NOD)-like receptor signaling pathway, and lipopolysaccharide biosynthesis, which coincided with lower inflammatory response and intestinal permeability in the piglets infected with HNZK-02-P150. In conclusion, the PDCoV HNZK-02 was successfully attenuated by serial passage , and the changes of S gene, metabolic function, and gut microbiota may contribute to the attenuation. The PDCoV HNZK-02-P150 may have the potential for developing live-attenuated vaccine.IMPORTANCEPorcine deltacoronavirus (PDCoV) is an enteropathogen causing severe diarrhea, dehydration, and death in nursing piglets, devastating great economic losses for the global swine industry, and has cross-species transmission and zoonotic potential. There are currently no approved treatments or vaccines available for PDCoV. In addition, gut microbiota has an important relationship with the development of many diseases. Here, the PDCoV virulent HNZK-02 strain was successfully attenuated by serial passage on cell cultures, and the pathogenesis and effects on the gut microbiota composition and metabolic function of the PDCoV HNZK-02-P5 and P150 strains were investigated in piglets. We also found the genetic changes in the S protein during passage and the gut microbiota may contribute to the pathogenesis of PDCoV, while their interaction molecular mechanism would need to be explored further.
Topics: Animals; Swine; Virulence; Gastrointestinal Microbiome; Serial Passage; Swine Diseases; Cell Culture Techniques; Diarrhea; Vaccines; Homeostasis
PubMed: 38349151
DOI: 10.1128/msystems.01346-23 -
Journal of Virology Feb 2024Porcine deltacoronavirus (PDCoV) has caused enormous economic losses to the global pig industry. However, the immune escape mechanism of PDCoV remains to be fully...
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.
Topics: Animals; Humans; Coronavirus 3C Proteases; Coronavirus Infections; Deltacoronavirus; Immunity, Innate; Interferon Type I; Intracellular Signaling Peptides and Proteins; Proteolysis; Signal Transduction; Swine; Swine Diseases; Transcription Factors; Viral Zoonoses; Virus Replication
PubMed: 38289117
DOI: 10.1128/jvi.01682-23 -
Journal of Virology Feb 2024HDAC6, a structurally and functionally unique member of the histone deacetylase (HDAC) family, is an important host factor that restricts viral infection. The...
HDAC6, a structurally and functionally unique member of the histone deacetylase (HDAC) family, is an important host factor that restricts viral infection. The broad-spectrum antiviral activity of HDAC6 makes it a potent antiviral agent. Previously, we found that HDAC6 functions to antagonize porcine deltacoronavirus (PDCoV), an emerging enteropathogenic coronavirus with zoonotic potential. However, the final outcome is typically a productive infection that materializes as cells succumb to viral infection, indicating that the virus has evolved sophisticated mechanisms to combat the antiviral effect of HDAC6. Here, we demonstrate that PDCoV nonstructural protein 5 (nsp5) can cleave HDAC6 at glutamine 519 (Q519), and cleavage of HDAC6 was also detected in the context of PDCoV infection. More importantly, the anti-PDCoV activity of HDAC6 was damaged by nsp5 cleavage. Mechanistically, the cleaved HDAC6 fragments (amino acids 1-519 and 520-1159) lost the ability to degrade PDCoV nsp8 due to their impaired deacetylase activity. Furthermore, nsp5-mediated cleavage impaired the ability of HDAC6 to activate RIG-I-mediated interferon responses. We also tested three other swine enteric coronaviruses (transmissible gastroenteritis virus, porcine epidemic diarrhea virus, and swine acute diarrhea syndrome-coronavirus) and found that all these coronaviruses have adopted similar mechanisms to cleave HDAC6 in both an overexpression system and virus-infected cells, suggesting that cleavage of HDAC6 is a common strategy utilized by swine enteric coronaviruses to antagonize the host's antiviral capacity. Together, these data illustrate how swine enteric coronaviruses antagonize the antiviral function of HDAC6 to maintain their infection, providing new insights to the interaction between virus and host.IMPORTANCEViral infections and host defenses are in constant opposition. Once viruses combat or evade host restriction, productive infection is achieved. HDAC6 is a broad-spectrum antiviral protein that has been demonstrated to inhibit many viruses, including porcine deltacoronavirus (PDCoV). However, whether HDAC6 is reciprocally targeted and disabled by viruses remains unclear. In this study, we used PDCoV as a model and found that HDAC6 is targeted and cleaved by nsp5, a viral 3C-like protease. The cleaved HDAC6 loses its deacetylase activity as well as its ability to degrade viral proteins and activate interferon responses. Furthermore, this cleavage mechanism is shared among other swine enteric coronaviruses. These findings shed light on the intricate interplay between viruses and HDAC6, highlighting the strategies employed by viruses to evade host antiviral defenses.
Topics: Animals; Coronavirus; Coronavirus Infections; Deltacoronavirus; Interferons; Swine; Swine Diseases
PubMed: 38289103
DOI: 10.1128/jvi.01814-23 -
Vaccines Dec 2023Swine enteric coronaviruses (SECs) cause significant economic losses to the pig industry in China. Although many commercialized vaccines against transmissible... (Review)
Review
Swine enteric coronaviruses (SECs) cause significant economic losses to the pig industry in China. Although many commercialized vaccines against transmissible gastroenteritis virus (TGEV) and porcine epidemic diarrhea virus (PEDV) are available, viruses are still widespread. The recent emergence of porcine deltacoronavirus (PDCoV) and swine acute diarrhea syndrome coronavirus (SADS-CoV), for which no vaccines are available, increases the disease burden. In this review, we first introduced the genomic organization and epidemiology of SECs in China. Then, we discussed the current vaccine development and application in China, aiming to provide suggestions for better prevention and control of SECs in China and other countries.
PubMed: 38276670
DOI: 10.3390/vaccines12010011 -
Virus Research Mar 2024Porcine deltacoronavirus (PDCoV) is a novel enteric coronavirus that can cause vomiting, watery diarrhea in pigs and the death of piglets. The open reading frame (ORF) 5...
Porcine deltacoronavirus (PDCoV) is a novel enteric coronavirus that can cause vomiting, watery diarrhea in pigs and the death of piglets. The open reading frame (ORF) 5 is one of the accessory genes in PDCoV genome and encodes an accessory protein NS6. To date, the function of NS6 is still unclear. In this study, the recombinant NS6 was successfully expressed in prokaryotic expression system and purified. To prepare monoclonal antibody (mAb), six-week-old female BALB/c mice were primed subcutaneously with purified NS6. A novel mouse mAb against NS6 was obtained and designated as 3D5. The isotype of 3D5 is IgG2b with kappa (κ) light chain. 3D5 can specifically recognizes the natural NS6 in swine testis (ST) cells infected with PDCoV and expressed NS6 in human embryonic kidney 293T (HEK 293T) cells transfected with mammalian vector. The minimal linear B cell epitope recognised by 3D5 on NS6 was VPELIDPLVK determined by peptide scanning and named EP-3D5. The sequence of EP-3D5 is completely conserved among PDCoV strains. Moreover, six to nine residues of EP-3D5 were identified to be conserved in non-PDCoV strains. These results provide valuable insights into the antigenic structure and function of NS6 in virus pathogenesis, and aid for the development of PDCoV epitope-associated diagnostics and vaccine design.
Topics: Male; Mice; Swine; Animals; Female; Humans; Deltacoronavirus; Swine Diseases; Diarrhea; Epitopes, B-Lymphocyte; Coronavirus Infections; Mammals
PubMed: 38262568
DOI: 10.1016/j.virusres.2024.199329