猪流行性腹泻病毒(PEDV)与抗病毒天然免疫

猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)是引起猪流行性腹泻病等肠道疾病的一种动物冠状病毒.PEDV与宿主系统相互作用,特别是其对宿主抗病毒天然免疫调节作用和机制是目前动物冠状病毒研究的基础科学问题之一.基于作者近几年来对人类重要冠状病毒对宿主抗病毒天然免疫系统调节作用的研究,本文对PEDV基因组与编码蛋白主要功能以及PEDV调节宿主抗病毒天然免疫反应及其可能机制的进展和现状进行了分析.与人类冠状病毒相似,PEDV编码的木瓜样蛋白酶(papain like protease,PLP)是一个多功能蛋白酶,除了蛋白酶活性外,还具有去泛素化酶(DUB)活性和宿主干扰素拮抗活性,是PEDV编码的一种新型病毒来源DUB和宿主干扰素拮抗蛋白.这些研究为阐明PEDV对宿主抗病毒天然免疫反应调节作用和其致病机制提供了重要的理论依据,为研制新型PEDV免疫防治措施提供了重要理论基础.     

猪流行性腹泻病毒核衣壳蛋白与感染细胞核磷蛋白的共定位分析

【目的】阐明猪流行性腹泻病毒(PEDV)核衣壳蛋白与病毒感染细胞核仁成分B23.1蛋白的共定位特征。【方法】分别参照GenBank中PEDV CV777株的N基因序列(AF353511)和编码人细胞核仁蛋白B23.1基因序列(BC050628.1),设计、合成扩增N基因和B23.1基因的引物,利用RT-PCR技术扩增了N基因和Vero E6细胞的B23.1基因的cDNA,分别克隆到真核表达载体pAcGFP1-C1和pDsRed2-N1,获得重组质粒pAcGFP1-C1/N和pDsRed2-N1/B23.1,共转染Vero E6细胞。【结果】Western blots分析表明这些融合蛋白在转染的Vero E6细胞中表达;共聚焦显微镜技术分析表明在共转染Vero E6细胞中猪流行性腹泻病毒N蛋白与Vero E6细胞核磷蛋白B23.1发生共定位。【结论】为进一步鉴定PEDV N蛋白中核仁定位信号和N蛋白核仁定位机制提供可靠依据。     

猪流行性腹泻病毒功能性受体的鉴定

为研究猪氨基肽酶(Porcine Aminopeptidase N,pAPN)是否作为猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV)的细胞感染受体,通过转染技术,使PEDV非容许性细胞MDCK表达pAPN,并用PEDV感染转染细胞。结果发现转染的MDCK细胞可以感染PEDV,并且该病毒可以在转染细胞中连续传代。免疫荧光法鉴定存在病毒抗原。进一步实验证实,抗pAPN血清可以抑制PEDV感染转染的MDCK细胞。这些结果展示转染的MDCK细胞、pAPN表达及PEDV病毒复制之间存在直接联系,证明pAPN是PEDV的细胞感染受体之一。     

Aminopeptidase N Knockout Pigs Are Not Resistant to Porcine Epidemic Diarrhea Virus Infection

<正>Dear Editor,Porcine epidemic diarrhea virus(PEDV) is the etiologic agent of porcine epidemic diarrhea(PED), which is an acute, highly contagious, and devastating enteric viral disease in pigs(Lee 2015). PEDV is a coronavirus that mainly infects and replicates in villous enterocytes of the small intestine in pigs(Li et al. 2016). PEDV can infect     

HMCES蛋白促进猪流行性腹泻病毒在Vero细胞中的复制

【目的】鉴定能够调控猪流行性腹泻病毒(porcine epidemic diarrhea virus,PEDV)复制的关键宿主蛋白。【方法】利用LC-MS/MS技术结合串联质谱标签(tandem mass tag,TMT)，分析PEDV感染Vero细胞36 h后和未感染组的蛋白组学差异。鉴定筛选了114个显著差异表达蛋白，其中宿主胚胎干细胞特异性5-羟甲基胞嘧啶结合蛋白(5-hydroxymethylcytosine binding,ES cell-specific protein,HMCES)显著上调。进一步构建HMCES真核表达质粒，通过蛋白免疫印迹和实时荧光定量PCR检测过表达HMCES对PEDV复制的影响；合成针对HMCES基因的特异性si RNA，利用Western blotting和RT-q PCR检测si RNA对HMCES表达的干扰效果及HMCES被干扰后对PEDV复制的影响。【结果】过表达HMCES能显著促进PEDV在Vero细胞中复制，并且复制水平随着HMCES的剂量递增呈现剂量依赖式增加；si RNA-341下调内源性HMCES表达进而抑制PEDV复制。【结论】H...     

A Single Point Mutation Creating a Furin Cleavage Site in the Spike Protein Renders Porcine Epidemic Diarrhea Coronavirus Trypsin Independent for Cell Entry and Fusion

The emerging porcine epidemic diarrhea virus (PEDV) requires trypsin supplementation to activate its S protein for membrane fusion and virus propagation in cell culture. By substitution of a single amino acid in the S protein, we created a recombinant PEDV with an artificial furin protease cleavage site N terminal of the putative fusion peptide (PEDV-S^FCS). PEDV-S^FCS exhibited trypsin-independent cell-cell fusion and was able to replicate in culture cells independently of trypsin, though to low titer.     

Complete Genome Sequence of Porcine Epidemic Diarrhea Virus Strain AJ1102 Isolated from a Suckling Piglet with Acute Diarrhea in China

A diarrhea outbreak caused by porcine epidemic diarrhea virus (PEDV) has been observed in China since December 2010. We report here the complete genome sequence of PEDV strain AJ1102 isolated from a suckling piglet with acute diarrhea, which will help toward understanding the molecular and evolutionary characteristics of the epidemic PEDV in China.     

Time-calibrated phylogenomics of the porcine epidemic diarrhea virus: genome-wide insights into the spatio-temporal dynamics

Porcine epidemic diarrhea virus (PEDV), the causative agent of porcine epidemic diarrhea (PED), has led to tremendous economic losses in the global swine industry. Although the phylogeny of PEDV has been investigated extensively at the molecular level, there was no time-calibrated phylogenomic study on the virus. To improve insight into this topic, we analyzed 138 published genome sequences using the Bayesian coalescent analyses as well as Bayesian inferences and maximum likelihood methods. All of the global PEDV isolates were divided into six groups, except for one unclassified isolate. Of the six groups, Groups 1–5 comprised pandemic viruses while the remaining Group 6 contained classical isolates. Interestingly, the two clades, both pandemic and classical, consisted of clade-specific amino acid sequences in five genes: ORF1a, ORF1b, S, ORF3, and N. Within the pandemic clade, Group 1 and Group 2 originated from North America, whereas Group 3–Group 5 were derived from Asia. In Group 2, there was a common origin of S INDEL isolates. Within each group, there was no apparent association between temporal or geographic origin and heterogeneity of PEDVs. Our findings also showed that the PEDV virus evolved at a rate of 3.38?×?10^?4 substitutions/site/year, and the most recent common ancestor of the virus emerged 75.9 years ago. Our Bayesian skyline plot analysis indicated that the PEDV had maintained constant effective population size excluding only a short period, around 2012, when a valley shaped decline in the effective number of infections occurred.     

In vitro antiviral activity of phlorotannins isolated from Ecklonia cava against porcine epidemic diarrhea coronavirus infection and hemagglutination

Despite the prepdominat agent causing severe entero-pathogenic diarrhea in swine, there are no effective therapeutical treatment of porcine epidemic diarrhea virus (PEDV). In this study, we evaluated the antiviral activity of five phlorotannins isolated from Ecklonia cava (E. cava) against PEDV. In vitro antiviral activity was tested using two different assay strategies: (1) blockage of the binding of virus to cells (simultaneous-treatment assay) and (2) inhibition of viral replication (post-treatment assay). In simultaneous-treatment assay, compounds 2–5 except compound 1 exhibited antiviral activities of a 50% inhibitory concentration (IC₅₀) with the ranging from 10.8 ± 1.4 to 22.5 ± 2.2 μM against PEDV. Compounds 1–5 were completely blocked binding of viral spike protein to sialic acids at less than 36.6 μM concentrations by hemagglutination inhibition. Moreover, compounds 4 and 5 of five phlorotannins inhibited viral replication with IC₅₀ values of 12.2 ± 2.8 and 14.6 ± 1.3 μM in the post-treatment assay, respectively. During virus replication steps, compounds 4 and 5 exhibited stronger inhibition of viral RNA and viral protein synthesis in late stages (18 and 24 h) than in early stages (6 and 12 h). Interestingly, compounds 4 and 5 inhibited both viral entry by hemagglutination inhibition and viral replication by inhibition of viral RNA and viral protein synthesis, but not viral protease. These results suggest that compounds isolated from E. cava have strong antiviral activity against PEDV, inhibiting viral entry and/or viral replication, and may be developed into natural therapeutic drugs against coronavirus infection.     

Proteome analysis of porcine epidemic diarrhea virus (PEDV)‐infected Vero cells

Porcine epidemic diarrhea virus (PEDV) causes an acute, highly contagious, and devastating viral enteric disease with a high mortality rate in suckling pigs. A large‐scale outbreak of PED occurred in China in 2010, with PEDV emerging in the United States in 2013 and spreading rapidly, posing significant economic and public health concerns. In this study, LC–MS/MS coupled to iTRAQ labeling was used to quantitatively identify differentially expressed cellular proteins in PEDV‐infected Vero cells. We identified 49 differentially expressed cellular proteins, of which 8 were upregulated and 41 downregulated. These differentially expressed proteins were involved in apoptosis, signal transduction, and stress responses. Based on these differentially expressed proteins, we propose that PEDV might utilize apoptosis and extracellular signal regulated kinases pathways for maximum viral replication. Our study is the first attempt to analyze the protein profile of PEDV‐infected cells by quantitative proteomics, and we believe our findings provide valuable information with respect to better understanding the host response to PEDV infection.     

猪流行性腹泻病毒S基因片段的克隆及原核表达

为研究猪流行性腹泻病毒(porcine epidemic diarrhea virus PEDV)S基因片段的原核表达产物是否具有抗原性,分析S基因抗原位点后,用PCR技术扩增S蛋白主要抗原区的核酸序列,经克隆后将目的片段连接到原核表达载体pET-28a(+)中,成功构建了重组质粒pET-28a-PEDV-Sp,其重组菌于37℃、0.5 mmol/L IPTG诱导表达4 h后进行SDS-PAGE分析,在分子质量约为29 kDa处出现一新蛋白带,与预期相符。质谱鉴定表明,已成功表达了目的蛋白。纯化后的重组蛋白免疫兔制备多克隆抗体,抗体效价检测结果显示该蛋白具有良好的抗原性。该研究为猪流行性腹泻基因工程疫苗的研制奠定基础。     

Role of proteases in the release of porcine epidemic diarrhea virus from infected cells

Porcine epidemic diarrhea virus (PEDV), a causative agent of pig diarrhea, requires a protease(s) for multicycle replication in cultured cells. However, the potential role of proteases in the infection process remains unclear. In order to explore this, we used two different approaches: we infected either Vero cells in the presence of trypsin or Vero cells that constitutively express the membrane-associated protease TMPRSS2 (Vero/TMPRSS2 cells). We found that PEDV infection was enhanced, and viruses were efficiently released into the culture fluid, from Vero cells infected in the presence of protease, while in cells without protease, the virus grew, but its release into the culture fluid was strongly hampered. Cell-to-cell fusion of PEDV-infected cells and cleavage of the spike (S) protein were observed in cells with protease. When infected Vero cells were cultured for 3 days in the absence of trypsin but were then treated transiently with trypsin, infectious viruses were immediately released from infected cells. In addition, treatment of infected Vero/TMPRSS2 cells with the protease inhibitor leupeptin strongly blocked the release of virus into the culture fluid. Under electron microscopy, PEDV-infected Vero cells, as well as PEDV-infected Vero/TMPRSS2 cells treated with leupeptin, retained huge clusters of virions on their surfaces, while such clusters were rarely seen in the presence of trypsin and the absence of leupeptin in Vero and Vero/TMPRSS2 cells, respectively. Thus, the present study indicates that proteases play an important role in the release of PEDV virions clustered on cells after replication occurs. This unique observation in coronavirus infection suggests that the actions of proteases are reminiscent of that of the influenza virus neuraminidase protein.     

Manipulation of the Porcine Epidemic Diarrhea Virus Genome Using Targeted RNA Recombination

Porcine epidemic diarrhea virus (PEDV) causes severe economic losses in the swine industry in China and other Asian countries. Infection usually leads to an acute, often lethal diarrhea in piglets. Despite the impact of the disease, no system is yet available to manipulate the viral genome which has severely hampered research on this virus until today. We have established a reverse genetics system for PEDV based on targeted RNA recombination that allows the modification of the 3′-end of the viral genome, which encodes the structural proteins and the ORF3 protein. Using this system, we deleted the ORF3 gene entirely from the viral genome and showed that the ORF3 protein is not essential for replication of the virus in vitro. In addition, we inserted heterologous genes (i.e. the GFP and Renilla luciferase genes) at two positions in the viral genome, either as an extra expression cassette or as a replacement for the ORF3 gene. We demonstrated the expression of both GFP and Renilla luciferase as well as the application of these viruses by establishing a convenient and rapid virus neutralization assay. The new PEDV reverse genetics system will enable functional studies of the structural proteins and the accessory ORF3 protein and will allow the rational design and development of next generation PEDV vaccines.     

Complete genome sequences of a Korean virulent porcine epidemic diarrhea virus and its attenuated counterpart

A virulent porcine epidemic diarrhea virus (PEDV) strain, DR13, was obtained from suckling pigs suspected of having porcine epidemic diarrhea in 1999 in Korea, and its attenuated counterpart was derived from virulent strain DR13 by serial propagation in Vero cells. This report describes the first complete genome sequences of virulent PEDV and its attenuated counterpart, which will provide important insights into the molecular basis of the attenuation of PEDV.     

Significant Inhibition of Porcine Epidemic Diarrhea Virus In Vitro by Remdesivir,Its Parent Nucleoside and β-d-N4-hydroxycytidine

Virologica Sinica - Porcine epidemic diarrhea (PED) caused by porcine epidemic diarrhea virus (PEDV) is widespread in the world. In recent years, the increased virulence of the virus due to viral...     

Development of a porcine epidemic diarrhea virus M protein-based ELISA for virus detection

A membrane (M), protein-based ELISA was developed to detect porcine epidemic diarrhea virus (PEDV). The M gene of PEDV was expressed in Escherichia coli. The purified recombinant M protein was used to immunize rabbits to generate a polyclonal antibody. Immunofluorescence analysis indicated that the anti-PEDV-M antibody reacted with PEDV-infected cells. The antibody was utilized to develop an indirect ELISA to detect PEDV. Other viruses, porcine transmissible gastroenteritis coronavirus, avian infectious bronchitis coronavirus, porcine reproductive and respiratory syndrome virus, classic swine fever virus and porcine pseudorabies virus, were unreactive.     

Cloning and sequence analysis of the Korean strain of spike gene of porcine epidemic diarrhea virus and expression of its neutralizing epitope in plants

Porcine epidemic diarrhea virus (PEDV) causes acute diarrhea and dehydration in pigs and leads to death with a high mortality rate, which has been reported notably in Korea. The spike (S) gene of the PEDV isolated in Korea was cloned and sequenced. The nucleotide sequence encoding the entire S gene open reading frame of Korean strain was 4161 bases long encoding 1387 amino acids. The neutralizing epitope of Korean PEDV (K-COE) was expressed in tobacco plants using Agrobacterium-mediated protein transformation. The recombinant K-COE constituted up to 0.1% of the total soluble protein in the leaves of transgenic tobacco plants. The result of this study opens the way for the development of an edible vaccine against PEDV infection in Korea.     

Complete Genome Sequence of a Variant Porcine Epidemic Diarrhea Virus Strain Isolated in China

Since October 2010, an outbreak of porcine epidemic diarrhea (PED) has been observed in some provinces of China. Here we report the complete genome sequence of porcine epidemic diarrhea virus (PEDV) strain LC, which was recently isolated from sucking piglets that suffered from severe watery diarrhea in Guangdong. It will help in understanding the epidemiological and molecular characteristics of PEDV in China.     

表达PEDV S和PoRV VP7蛋白的重组伪狂犬毒株构建

【背景】猪流行性腹泻、猪轮状病毒病与猪伪狂犬病是严重危害全球养猪业的3种重要传染病,混合感染往往导致猪场更严重的损失。【目的】利用同源重组技术构建共表达猪流行性腹泻病毒(Porcine epidemic diarrhea virus,PEDV) S蛋白和猪轮状病毒(Rotavirus,PoRV) VP7蛋白的猪伪狂犬三联基因工程疫苗株,并研究其部分生物学特性。【方法】通过序列比对、蛋白结构分析筛选s基因的475?804 aa和vp7基因的17?339 aa作为毒株构建的目的片段,依次构建了pMD-S、pMD-VP7、pMD-VP7.S克隆载体和pEGFP-VP7.S转移载体。将质粒pEGFP-VP7.S和PRV XJ亲本株同源重组,空斑纯化得到重组毒株PRV (CM),对其稳定性和增殖特性进行研究。【结果】构建了共表达S蛋白和VP7蛋白的伪狂犬基因工程病毒,连续传代20次,均能检测到vp7和s基因,而gE基因阴性;Western blotting证实2种外源基因在重组病毒中均能实现良好的表达;测定亲本毒株和重组毒株的TCID50分别是10?7.59/0.1 mL和10?7.25/0.1 mL。【结论】获得了伪狂犬基因工程重组弱毒株PRV (CM),外源基因稳定存在,毒力基因稳定缺失,增殖特性差异不大,为PRV、PEDV和PoRV基因工程三联苗研究奠定了基础。     

Expression of neutralizing epitope of porcine epidemic diarrhea virus in potato plants

Transgenic plants expressing recombinant proteins from pathogenic microorganisms provide an inexpensive edible vaccine for induction of local immunity. A neutralizing epitope of porcine epidemic diarrhea virus (PEDV) gene containing SEKDEL was expressed in potato using Agrobacterium-mediated transformation system. Putative transgenic plants were regenerated, and genomic PCR confirmed the presence of PEDV epitope gene in the potato plants. Based on the ELISA results, epitope of PEDV protein made up approximately 0.1% of the total soluble tuber protein.