scholarly journals The S Gene Is Necessary but Not Sufficient for the Virulence of Porcine Epidemic Diarrhea Virus Novel Variant Strain BJ2011C

2018 ◽  
Vol 92 (13) ◽  
Author(s):  
Di Wang ◽  
Xinna Ge ◽  
Dongjie Chen ◽  
Jie Li ◽  
Yueqi Cai ◽  
...  
Keyword(s):  
Porcine Epidemic Diarrhea Virus ◽  
Vaccine Development ◽  
Economic Losses ◽  
Avirulent Strain ◽  
Diarrhea Virus ◽  
Severe Diarrhea ◽  
S Gene ◽  
Viral Virulence ◽  
Porcine Epidemic Diarrhea ◽  
Highly Virulent

ABSTRACT The recently emerged highly virulent variants of porcine epidemic diarrhea virus (PEDV) have caused colossal economic losses to the worldwide swine industry. In this study, we investigated the viral virulence determinants by constructing a series of chimeric mutants between the highly virulent strain BJ2011C and the avirulent strain CHM2013. When tested in the 2-day-old piglet model, wild-type (WT) BJ2011C caused severe diarrhea and death of the piglets within 72 h. In contrast, its chimeric derivative carrying the S gene from CHM2013 (BJ2011C-S CHM ) was avirulent to the piglets. Moreover, reciprocal substitution of the BJ2011C S gene (CHM2013-S BJ ) did not enable CHM2013 to gain any virulence. However, when the whole structural protein-coding region of BJ2011C (CHM2013-SP BJ ) was swapped, CHM2013 started to gain the ability to efficiently colonize the intestinal tract and caused diarrhea in piglets. A further gain of virulence required additional acquisition of the 3′ untranslated region (UTR) of BJ2011C, and the resultant virus (CHM2013-SP + 3UTR BJ ) caused more severe diarrhea and death of piglets. Together, our findings suggest that the virulence of PEDV epidemic strains is a multigenic event and that the S gene is only one of the necessary determinants. IMPORTANCE The recently emerged highly virulent PEDV variants are the major cause of the global porcine epidemic diarrhea (PED) pandemic. The S gene of the variants undergoes remarkable variations and has been thought to be the virulence determinant for the enhanced pathogenesis. Our studies here showed that the S gene is only part of the story and that full virulence requires cooperation from other genes. Our findings provide insight into the pathogenic mechanism of the highly virulent PEDV variants and have implications for future vaccine development.

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

Viruses ◽  
2019 ◽  
Vol 12 (1) ◽  
pp. 41 ◽  
Author(s):  
Chi-Fei Kao ◽  
Hui-Wen Chang
Keyword(s):  
Mortality Rate ◽  
Porcine Epidemic Diarrhea Virus ◽  
Rational Design ◽  
Economic Losses ◽  
Diarrhea Virus ◽  
Viral Shedding ◽  
S Gene ◽  
Porcine Epidemic Diarrhea ◽  
Highly Virulent

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

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

2019 ◽  
Vol 93 (15) ◽  
Author(s):  
Yixuan Hou ◽  
Hanzhong Ke ◽  
Jineui Kim ◽  
Dongwan Yoo ◽  
Yunfang Su ◽  
...  
Keyword(s):  
Porcine Epidemic Diarrhea Virus ◽  
Vaccine Development ◽  
Vaccine Candidate ◽  
Spike Protein ◽  
Economic Losses ◽  
High Dose ◽  
Type I ◽  
Viral Pathogen ◽  
Diarrhea Virus ◽  
Porcine Epidemic Diarrhea

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

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

2020 ◽  
Vol 7 ◽  
Author(s):  
Linyang Yu ◽  
Yanling Liu ◽  
Shuangyun Wang ◽  
Leyi Zhang ◽  
Pengshuai Liang ◽  
...  
Keyword(s):  
Porcine Epidemic Diarrhea Virus ◽  
Vero Cells ◽  
Economic Losses ◽  
Molecular Characteristics ◽  
Phylogenetic Tree Analysis ◽  
Genetic Characteristics ◽  
Diarrhea Virus ◽  
Severe Diarrhea ◽  
Positive Rate ◽  
Porcine Epidemic Diarrhea

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

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

Viruses ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 391 ◽  
Author(s):  
Pengwei Zhao ◽  
Song Wang ◽  
Zhi Chen ◽  
Jiang Yu ◽  
Rongzhi Tang ◽  
...  
Keyword(s):  
Amino Acids ◽  
Porcine Epidemic Diarrhea Virus ◽  
Vero Cells ◽  
Economic Losses ◽  
Diarrhea Virus ◽  
S Gene ◽  
Successive Passage ◽  
Porcine Epidemic Diarrhea

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

scholarly journals Porcine Epidemic Diarrhea Virus 3C-Like Protease-Mediated Nucleocapsid Processing: Possible Link to Viral Cell Culture Adaptability

2016 ◽  
Vol 91 (2) ◽  
Author(s):  
Peera Jaru-Ampornpan ◽  
Juggragarn Jengarn ◽  
Asawin Wanitchang ◽  
Anan Jongkaewwattana
Keyword(s):  
Cell Culture ◽  
Growth Retardation ◽  
Porcine Epidemic Diarrhea Virus ◽  
Vaccine Development ◽  
Wild Type Virus ◽  
Economic Losses ◽  
Swine Industry ◽  
Diarrhea Virus ◽  
Porcine Epidemic Diarrhea

ABSTRACT Porcine epidemic diarrhea virus (PEDV) causes severe diarrhea and high mortality rates in newborn piglets, leading to massive losses to the swine industry worldwide during recent epidemics. Intense research efforts are now focusing on defining viral characteristics that confer a growth advantage, pathogenicity, or cell adaptability in order to better understand the PEDV life cycle and identify suitable targets for antiviral or vaccine development. Here, we report a unique phenomenon of PEDV nucleocapsid (N) cleavage by the PEDV-encoded 3C-like protease (3Cpro) during infection. The identification of the 3Cpro cleavage site at the C terminus of N supported previous observations that PEDV 3Cpro showed a substrate requirement slightly different from that of severe acute respiratory syndrome coronavirus (SARS-CoV) 3Cpro and revealed a greater flexibility in its substrate recognition site. This cleavage motif is present in the majority of cell culture-adapted PEDV strains but is missing in emerging field isolates. Remarkably, reverse-genetics-derived cell culture-adapted PEDVAVCT12 harboring uncleavable N displayed growth retardation in Vero E6-APN cells compared to the wild-type virus. These observations altogether shed new light on the investigation and characterization of the PEDV nucleocapsid protein and its possible link to cell culture adaptation. IMPORTANCE Recurrent PEDV outbreaks have resulted in enormous economic losses to swine industries worldwide. To gain the upper hand in combating this disease, it is necessary to understand how this virus replicates and evades host immunity. Characterization of viral proteins provides important clues to mechanisms by which viruses survive and spread. Here, we characterized an intriguing phenomenon in which the nucleocapsids of some PEDV strains are proteolytically processed by the virally encoded main protease. Growth retardation in recombinant PEDV carrying uncleavable N suggests a replication advantage provided by the cleavage event, at least in the cell culture system. These findings may direct us to a more complete understanding of PEDV replication and pathogenicity.

scholarly journals Complete Genome Sequence of a Porcine Epidemic Diarrhea Virus Strain from Vietnam, HUA-14PED96, with a Large Genomic Deletion

2016 ◽  
Vol 4 (1) ◽  
Author(s):  
Se-Eun Choe ◽  
Kee-Hwan Park ◽  
Seong-In Lim ◽  
Van Phan Le ◽  
Nguyen Ba Hien ◽  
...  
Keyword(s):  
Complete Genome Sequence ◽  
Porcine Epidemic Diarrhea Virus ◽  
Virulent Strain ◽  
Open Reading Frame ◽  
High Identity ◽  
Reading Frame ◽  
Diarrhea Virus ◽  
Severe Diarrhea ◽  
Porcine Epidemic Diarrhea ◽  
Highly Virulent

A highly virulent strain of Porcine epidemic diarrhea virus (PEDV) causing severe diarrhea has recently emerged in Vietnam. Genomic sequences from a novel strain, HUA-14PED96, isolated from a Vietnamese piglet with serious diarrhea show relatively high identity with U.S.-like PEDV strains, and have a 72-nt deletion in the open reading frame 1a (ORF1a) gene.

scholarly journals Expression of the recombinant C-terminal of the S1 domain and N-terminal of the S2 domain of the spike protein of porcine epidemic diarrhea virus

2021 ◽  
pp. 2913-2918
Author(s):  
Jiraporn Sritun ◽  
Natnaree Inthong ◽  
Siriluk Jala ◽  
Sakuna Phatthanakunanan ◽  
Khomson Satchasataporn ◽  
...  
Keyword(s):  
Induction Time ◽  
Porcine Epidemic Diarrhea Virus ◽  
Polyclonal Antibodies ◽  
Optimum Concentration ◽  
Economic Losses ◽  
S Protein ◽  
Thai Isolate ◽  
Diarrhea Virus ◽  
S Gene ◽  
Porcine Epidemic Diarrhea

Background and Aim: Porcine epidemic diarrhea virus (PEDV) causes severe diarrhea in suckling piglets, leading to severe economic losses in the swine industry. Commercial vaccines have limited effectiveness against different genogroups of PEDV and the shedding of virus. The C-terminal of the S1 domain and the N-terminal of the S2 domain (S1-2) protein of the spike (S) protein have four neutralizing epitopes. However, research on the expression of the S1-2 segment of the S gene has been limited. In this study, we expressed a recombinant S1-2 protein of the S protein of the PEDV Thai isolate and characterized the immunological properties of the recombinant S1-2 protein. Materials and Methods: The S1-2 segment of the S gene of the PEDV Thai isolate (G2b) was amplified, cloned into the pBAD202/D-TOPO® vector (Invitrogen, Carlsbad, CA, USA), and expressed in Escherichia coli. The optimum concentration of arabinose and the optimum induction time for the expression of the recombinant S1-2 protein were determined using sodium dodecyl sulfate-polyacrylamide gel electrophoresis. The immunogenic reactivity of the recombinant S1-2 protein was determined using Western blot analysis with rabbit polyclonal antibodies against the SM98 strain of PEDV (G1a). Results: The recombinant S1-2 segment of the S gene of the PEDV Thai isolate protein was cloned and the recombinant S1-2 protein was successfully expressed. The optimum concentration of arabinose and the optimum induction time for the induction of the recombinant S1-2 protein were 0.2% and 8 h, respectively. The recombinant S1-2 protein reacted specifically with both rabbit anti-histidine polyclonal antibodies and rabbit anti-PEDV polyclonal antibodies. Conclusion: The recombinant S1-2 protein reacted with rabbit anti-PEDV polyclonal antibodies induced by the different PEDV genogroup. Therefore, the recombinant S1-2 protein may be a useful tool for the development of a diagnostic test for PEDV or for a vaccine against PEDV.

scholarly journals Emerging Highly Virulent Porcine Epidemic Diarrhea Virus: Molecular Mechanisms of Attenuation and Rational Design of Live Attenuated Vaccines

2019 ◽  
Vol 20 (21) ◽  
pp. 5478 ◽  
Author(s):  
Yixuan Hou ◽  
Qiuhong Wang
Keyword(s):  
Porcine Epidemic Diarrhea Virus ◽  
Rational Design ◽  
Molecular Mechanisms ◽  
Current Knowledge ◽  
Economic Losses ◽  
Live Attenuated Vaccines ◽  
Diarrhea Virus ◽  
Porcine Epidemic Diarrhea ◽  
Highly Virulent

The highly virulent porcine epidemic diarrhea virus (PEDV) emerged in China in 2010. It infects pigs of all ages, and causes severe diarrhea and high mortality rates in newborn pigs, leading to devastating economic losses in the pork industry worldwide. Effective and safe vaccines against highly virulent PEDV strains are still unavailable, hampering the further prevention, control and eradication of the disease in herds. Vaccination of pregnant sows with live attenuated vaccines (LAVs) is the most effective strategy to induce lactogenic immunity in the sows, which provides A passive protection of suckling piglets against PEDV via the colostrum (beestings, or first milk) and milk. Several LAV candidates have been developed via serially passaging the highly virulent PEDV isolates in non-porcine Vero cells. However, their efficacies in the induction of sufficient protection against virulent PEDV challenge vary in vivo. In this review, we summarize the current knowledge of the virulence-related mutations of PEDV and their potential roles in PEDV attenuation in vivo. With the successful development of reverse genetics systems for PEDV, we also discuss how to use them to generate promising LAV candidates that are safe, effective and genetically stable. This article provides timely insight into the rational design of effective and safe PEDV LAV candidates.

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

Genes ◽  
2018 ◽  
Vol 9 (12) ◽  
pp. 591
Author(s):  
Tsung-Lin Tsai ◽  
Chen-Chang Su ◽  
Ching-Chi Hsieh ◽  
Chao-Nan Lin ◽  
Hui-Wen Chang ◽  
...  
Keyword(s):  
Gene Expression ◽  
Porcine Epidemic Diarrhea Virus ◽  
The Body ◽  
Economic Losses ◽  
Viral Gene ◽  
Sequence Motif ◽  
Cis Acting ◽  
Diarrhea Virus ◽  
Porcine Epidemic Diarrhea ◽  
In Cis

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

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