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Lee D, Kim S, Gim Y, Lee C. Genotypic characterization of novel S-DEL variants of porcine epidemic diarrhea virus identified in South Korea. Arch Virol 2024; 169:158. [PMID: 38970647 DOI: 10.1007/s00705-024-06088-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2024] [Accepted: 05/24/2024] [Indexed: 07/08/2024]
Abstract
The highly pathogenic genotype 2b (HP-G2b) of porcine epidemic diarrhea virus (PEDV), which caused a pandemic in 2013-2014, evolved in South Korea and became endemic, affecting the domestic pig industry. This study describes the genotypic traits of novel HP-G2b PEDV strains identified on affected farms experiencing low disease severity with < 10% neonatal mortality. Nucleotide sequencing revealed common deletion patterns, termed S-DEL2, resulting in a two-amino-acid deletion at positions 60 and 61, 61 and 62, or 63 and 64 in the N-terminal domain of the spike (S) protein of all isolates. The S barcode profiles of S-DEL2 variants differed from each other and shared 96.0-99.4% and 98.5-99.6% nt sequence identity with other South Korean HP-G2b PEDV strains in the S gene and in the complete genome sequence, respectively. Genetic and phylogenetic analysis showed that the S-DEL2 strains belonged to diverse domestic clades: CK, CK.1, CK.2, or NC. The emergence of novel S-DEL2 strains suggests that continuous evolution of PEDV occurs under endemic circumstances, resulting in genetic diversity and distinct clinical presentations. This study advances our knowledge regarding the genetic and pathogenic heterogeneity of PEDV and emphasizes the importance of active monitoring and surveillance to identify novel variants and determine their genotypic and phenotypic characteristics.
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Affiliation(s)
- Duri Lee
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Sungrae Kim
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Yunhee Gim
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju, 52828, Republic of Korea
| | - Changhee Lee
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju, 52828, Republic of Korea.
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Suwan P, Boonsoongnern A, Phuttapatimok S, Sukmak M, Jirawattanapong P, Chumsing W, Boodde O, Woramahatthanon K, Woonwong Y. Effectiveness of gilt acclimatization - improvement procedures in a farm with recurrent outbreaks of porcine epidemic diarrhea. Vet World 2023; 16:1695-1701. [PMID: 37766703 PMCID: PMC10521180 DOI: 10.14202/vetworld.2023.1695-1701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2023] [Accepted: 07/18/2023] [Indexed: 09/29/2023] Open
Abstract
Background and Aim Porcine epidemic diarrhea (PED) is a severe infectious disease that causes very high mortality in newborn piglets up to 2-3 weeks age. The main cause of repeated outbreaks of PED in infected farms is the continuing circulation of the PED virus (PEDV). Improper gilt management, including inappropriate gut feedback, commingling, and inadequate immunization, causes a prolonged virus circulation in breeding herds. Moreover, insufficient transfer of passive immunity through the colostrum to newborn piglets can also increase infection risk. Therefore, a gilt management program that controls infection should focus on infection monitoring and acclimatization. We investigated the source of recurrent PEDV outbreaks and examined how the effect of immunization methods, specifically using gut feedback mechanism and vaccination, can reduce PEDV circulation and improve immune responses in replacement gilts. Materials and Methods The study site was a segregated commercial production farm with endemic PEDV. The acclimatization methods included gut feedback and vaccination. This longitudinal study evaluated two strategies of gilt acclimatization against PEDV: Program 1 (routine farm management) and Program 2 (early feedback program and all-in-all-out system). Levels of PED RNA in fecal samples were measured using quantitative reverse transcription-polymerase chain reaction, and the PEDV S gene was sequenced. Porcine epidemic diarrhea-specific immune responses were assessed using enzyme-linked immunosorbent assay and the serum neutralization test. Results Porcine epidemic diarrhea outbreaks occurred in the farrowing, nursery, and finishing units and farrowed litters 5-10 days old were symptomatic of PED. Phylogenetic analyses of the S gene showed PEDV sequence divergence between PEDV field strains and vaccine strain, which may contribute to periodic outbreaks and continued persistence of PEDV in the farm. After gut feedback and acclimatization, replacement gilts from Program 1 continued to shed PEDV before being introduced to sow herds, while those from Program 2 did not shed PEDV before being introduced to sow herds. However, the components of the immune response against PEDV in serum samples, including specific immunoglobulin (Ig)G, specific IgA, and neutralizing antibodies were lower in gilts of Program 2 than those in Program 1. Conclusion We speculate that implementing the appropriate gilt acclimatization program can control PEDV circulation in farm. However, the acclimatization methods in Program 2 did not induce a strong and adequate immune response in replacement gilts. Therefore, maternal immunity levels and the degree of protection against PEDV require further study.
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Affiliation(s)
- Pimpakarn Suwan
- Graduate Program in Veterinary Clinical Studies, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Alongkot Boonsoongnern
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Sahathat Phuttapatimok
- Kamphaengsaen Veterinary Diagnostic Center, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Manakorn Sukmak
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Pichai Jirawattanapong
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Wilairat Chumsing
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Orawan Boodde
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Krithiran Woramahatthanon
- Kamphaengsaen Veterinary Diagnostic Center, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
| | - Yonlayong Woonwong
- Department of Farm Resources and Production Medicine, Faculty of Veterinary Medicine, Kasetsart University, Kamphaeng Saen, Nakhon Pathom, 73140, Thailand
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Jang G, Lee D, Shin S, Lim J, Won H, Eo Y, Kim CH, Lee C. Porcine epidemic diarrhea virus: an update overview of virus epidemiology, vaccines, and control strategies in South Korea. J Vet Sci 2023; 24:e58. [PMID: 37532301 PMCID: PMC10404706 DOI: 10.4142/jvs.23090] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Revised: 05/30/2023] [Accepted: 06/04/2023] [Indexed: 08/04/2023] Open
Abstract
Porcine epidemic diarrhea virus (PEDV) has posed significant financial threats to the domestic pig industry over the last three decades in South Korea. PEDV infection will mostly result in endemic persistence in the affected farrow-to-finish (FTF) herds, leading to endemic porcine epidemic diarrhea (PED) followed by year-round recurrent outbreaks. This review aims to encourage collaboration among swine producers, veterinarians, and researchers to offer answers that strengthen our understanding of PEDV in efforts to prevent and control endemic PED and to prepare for the next epidemics or pandemics. We found that collaboratively implementing a PED risk assessment and customized four-pillar-based control measures is vital to interrupt the chain of endemic PED in affected herds: the former can identify on-farm risk factors while the latter aims to compensate for or improve weaknesses via herd immunity stabilization and virus elimination. Under endemic PED, long-term virus survival in slurry and asymptomatically infected gilts ("Trojan Pigs") that can transmit the virus to farrowing houses are key challenges for PEDV eradication in FTF farms and highlight the necessity for active monitoring and surveillance of the virus in herds and their environments. This paper underlines the current knowledge of molecular epidemiology and commercially available vaccines, as well as the risk assessment and customized strategies to control PEDV. The intervention measures for stabilizing herd immunity and eliminating virus circulation may be the cornerstone of establishing regional or national PED eradication programs.
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Affiliation(s)
- Guehwan Jang
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju 52828, Korea
| | - Duri Lee
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju 52828, Korea
| | - Sangjune Shin
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju 52828, Korea
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea
| | - Jeonggyo Lim
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea
| | - Hokeun Won
- ChoongAng Vaccine Laboratories, Daejeon 34055, Korea
| | - Youngjoon Eo
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju 52828, Korea
- Nawoo Veterinary Group, Yangsan 50573, Korea
| | - Cheol-Ho Kim
- Gyeongnam Veterinary Service Laboratory Quarantine Agency, Jinju 52733, Korea
| | - Changhee Lee
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju 52828, Korea.
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Lee D, Jang G, Min KC, Lee IH, Won H, Yoon IJ, Kang SC, Lee C. Coinfection with porcine epidemic diarrhea virus and Clostridium perfringens type A enhances disease severity in weaned pigs. Arch Virol 2023; 168:166. [PMID: 37217624 DOI: 10.1007/s00705-023-05798-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 04/25/2023] [Indexed: 05/24/2023]
Abstract
Clostridium perfringens is a constituent of the normal gut microbiome in pigs; however, it can potentially cause pre- and post-weaning diarrhea. Nevertheless, the importance of this bacterium as a primary pathogen of diarrhea in piglets needs to be better understood, and the epidemiology of C. perfringens in Korean pig populations is unknown. To study the prevalence and typing of C. perfringens, 203 fecal samples were collected from diarrheal piglets on 61 swine farms during 2021-2022 and examined for the presence of C. perfringens and enteric viruses, including porcine epidemic diarrhea virus (PEDV). We determined that the most frequently identified type of C. perfringens was C. perfringens type A (CPA; 64/203, 31.5%). Among the CPA infections, single infections with CPA (30/64, 46.9%) and coinfections with CPA and PEDV (29/64, 45.3%) were the most common in diarrheal samples. Furthermore, we conducted animal experiments to investigate the clinical outcome of single infections and coinfections with highly pathogenic (HP)-PEDV and CPA in weaned piglets. The pigs infected with HP-PEDV or CPA alone showed mild or no diarrhea, and none of them died. However, animals that were co-inoculated with HP-PEDV and CPA showed more-severe diarrheal signs than those of the singly infected pigs. Additionally, CPA promoted PEDV replication in coinfected piglets, with high viral titers in the feces. A histopathological examination revealed more-severe villous atrophy in the small intestine of coinfected pigs than in singly infected pigs. This indicates a synergistic effect of PEDV and CPA coinfection on clinical disease in weaned piglets.
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Affiliation(s)
- Duri Lee
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, 52828, Jinju, Republic of Korea
| | - Guehwan Jang
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, 52828, Jinju, Republic of Korea
| | - Kyeng-Cheol Min
- ChoongAng Vaccine Laboratories, 34055, Daejeon, Republic of Korea
| | - Inn Hong Lee
- ChoongAng Vaccine Laboratories, 34055, Daejeon, Republic of Korea
| | - Hokeun Won
- ChoongAng Vaccine Laboratories, 34055, Daejeon, Republic of Korea
| | - In-Joong Yoon
- ChoongAng Vaccine Laboratories, 34055, Daejeon, Republic of Korea
| | | | - Changhee Lee
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, 52828, Jinju, Republic of Korea.
- College of Veterinary Medicine, Gyeongsang National University, 52828, Jinju, Republic of Korea.
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Bai J, Du C, Lu Y, Wang R, Su X, Yu K, Qin Q, Chen Y, Wei Z, Huang W, Ouyang K. Phylogenetic and Spatiotemporal Analyses of Porcine Epidemic Diarrhea Virus in Guangxi, China during 2017–2022. Animals (Basel) 2023; 13:ani13071215. [PMID: 37048471 PMCID: PMC10093014 DOI: 10.3390/ani13071215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2023] [Revised: 03/24/2023] [Accepted: 03/26/2023] [Indexed: 04/03/2023] Open
Abstract
Since 2010, porcine epidemic diarrhea virus (PEDV) has swept across China and spread throughout the country, causing huge economic losses. In this study, 673 diarrhea samples from 143 pig farms in Guangxi during 2017–2022 were collected and detected for PEDV. Ninety-eight strains were selected for S1 gene analyses and these strains were classified into four subgroups (G1b, G2a, G2b and G2c), accounting for 1.02 (1/98), 75.51 (74/98), 16.33 (16/98) and 7.14% (7/98) of the total, respectively. Importantly, an increased number of strains in the G2c subgroup was found from 2019 onwards. Bayesian analysis revealed that Guigang may have been the epicenter of PEDVs in Guangxi. In addition, Guigang was identified as the primary hub from which PEDVs spread via two routes, namely Guigang–Wuzhou and Guigang–Laibin. Moreover, several coinfections of novel PEDV variants bearing large deletions in the partial S1 protein and PEDVs possessing an intact partial S1 protein were found in pigs. Further recombination analyses indicated that two of the strains, 18-GXNN-6 and 19-GXBH-2, originated from intra-genogroup recombination. Together, our data revealed a new profile of PEDV in Guangxi, China, which enhances our understanding of the distribution, genetic characteristics and evolutionary profile of the circulating PEDV strains in China.
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Affiliation(s)
- Jiaguo Bai
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
| | - Chen Du
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
| | - Ying Lu
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
| | - Ruomu Wang
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
| | - Xueli Su
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
| | - Kechen Yu
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
| | - Qiuying Qin
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
| | - Ying Chen
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Nanning 530005, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Nanning 530005, China
- Key Laboratory of Prevention and Control for Animal Disease, Guangxi University, Nanning 530005, China
| | - Zuzhang Wei
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Nanning 530005, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Nanning 530005, China
- Key Laboratory of Prevention and Control for Animal Disease, Guangxi University, Nanning 530005, China
| | - Weijian Huang
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Nanning 530005, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Nanning 530005, China
- Key Laboratory of Prevention and Control for Animal Disease, Guangxi University, Nanning 530005, China
| | - Kang Ouyang
- Laboratory of Animal Infectious Diseases and Molecular Immunology, College of Animal Science and Technology, Guangxi University, Nanning 530005, China
- Guangxi Zhuang Autonomous Region Engineering Research Center of Veterinary Biologics, Nanning 530005, China
- Guangxi Key Laboratory of Animal Breeding, Disease Control and Prevention, Nanning 530005, China
- Key Laboratory of Prevention and Control for Animal Disease, Guangxi University, Nanning 530005, China
- Correspondence:
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Jang G, Min KC, Lee IH, Won H, Yoon IJ, Kang SC, Lee C. Deletion of pentad residues in the N-terminal domain of spike protein attenuates porcine epidemic diarrhea virus in piglets. Vet Microbiol 2023; 280:109727. [PMID: 36958068 DOI: 10.1016/j.vetmic.2023.109727] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Revised: 03/16/2023] [Accepted: 03/18/2023] [Indexed: 03/25/2023]
Abstract
Our previous study revealed that tissue culture-adapted porcine epidemic diarrhea virus (PEDV) strains, namely KNU-141112-S DEL2/ORF3 and -S DEL5/ORF3, were attenuated to different extents in vivo, suggesting that their independent deletion (DEL) signatures, including 2-amino acid (aa; residues 56-57) or 5-aa (residues 56-60) DEL in the N-terminal domain (NTD) of the spike (S) protein, may contribute to the reduced virulence of each strain. To investigate whether each DEL in the NTD of the S1 subunit is a determinant for the virulence of PEDV, we generated two mutant viruses, named icS DEL2 and icS DEL5, by introducing the identical double or quintuple aa DEL into S1 using reverse genetics with an infectious cDNA clone of KNU-141112 (icKNU-141112). We then orally inoculated conventional suckling piglets with icKNU-141112, icS DEL2, or icS DEL5 to compare their pathogenicities. The virulence of both DEL mutant viruses was significantly diminished compared to that of icKNU-141112, which causes severe clinical signs and 100 % mortality. Interestingly, the degree of attenuation differed between the two mutant viruses: icS DEL5 caused neither diarrhea nor mortality, whereas icS DEL2 caused mild to moderate diarrhea, higher viral titers in feces and intestinal tissues, and 25 % mortality. Furthermore, the icS DEL5-infected piglets displayed no remarkable macroscopic and microscopic intestinal lesions, while the icS DEL2-infected piglets showed histopathological changes in small intestine tissues, including moderate-to-severe villous atrophy. Our data indicate that the loss of the pentad (56GENQG60) residues in S alone can be sufficient to give rise to an attenuated phenotype of PEDV.
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Affiliation(s)
- Guehwan Jang
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju 52828, Republic of Korea
| | - Kyeng-Cheol Min
- ChoongAng Vaccine Laboratories, Daejeon 34055, Republic of Korea
| | - Inn Hong Lee
- ChoongAng Vaccine Laboratories, Daejeon 34055, Republic of Korea
| | - Hokeun Won
- ChoongAng Vaccine Laboratories, Daejeon 34055, Republic of Korea
| | - In-Joong Yoon
- ChoongAng Vaccine Laboratories, Daejeon 34055, Republic of Korea
| | | | - Changhee Lee
- College of Veterinary Medicine and Virus Vaccine Research Center, Gyeongsang National University, Jinju 52828, Republic of Korea.
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Trostle P, Corzo CA, Reich BJ, Machado G. A discrete-time survival model for porcine epidemic diarrhoea virus. Transbound Emerg Dis 2022; 69:3693-3703. [PMID: 36217910 PMCID: PMC10369857 DOI: 10.1111/tbed.14739] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2022] [Revised: 09/30/2022] [Accepted: 10/03/2022] [Indexed: 02/07/2023]
Abstract
Since the arrival of porcine epidemic diarrhea virus (PEDV) in the United States in 2013, elimination and control programmes have had partial success. The dynamics of its spread are hard to quantify, though previous work has shown that local transmission and the transfer of pigs within production systems are most associated with the spread of PEDV. Our work relies on the history of PEDV infections in a region of the southeastern United States. This infection data is complemented by farm-level features and extensive industry data on the movement of both pigs and vehicles. We implement a discrete-time survival model and evaluate different approaches to modelling the local-transmission and network effects. We find strong evidence in that the local-transmission and pig-movement effects are associated with the spread of PEDV, even while controlling for seasonality, farm-level features and the possible spread of disease by vehicles. Our fully Bayesian model permits full uncertainty quantification of these effects. Our farm-level out-of-sample predictions have a receiver-operating characteristic area under the curve (AUC) of 0.779 and a precision-recall AUC of 0.097. The quantification of these effects in a comprehensive model allows stakeholders to make more informed decisions about disease prevention efforts.
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Affiliation(s)
- Parker Trostle
- Department of Statistics, North Carolina State University, Raleigh, North Carolina, USA
| | - Cesar A Corzo
- Veterinary Population Medicine Department, College of Veterinary Medicine, University of Minnesota, Saint Paul, Minnesota, USA
| | - Brian J Reich
- Department of Statistics, North Carolina State University, Raleigh, North Carolina, USA
| | - Gustavo Machado
- Department of Population Health and Pathobiology, College of Veterinary Medicine, North Carolina State University, Raleigh, North Carolina, USA
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Development of a Next-Generation Vaccine Platform for Porcine Epidemic Diarrhea Virus Using a Reverse Genetics System. Viruses 2022; 14:v14112319. [PMID: 36366417 PMCID: PMC9692715 DOI: 10.3390/v14112319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2022] [Revised: 10/14/2022] [Accepted: 10/21/2022] [Indexed: 11/06/2022] Open
Abstract
For the past three decades, the porcine epidemic diarrhea virus (PEDV) has remained an enormous threat to the South Korean swine industry. The scarcity of an effective method for manipulating viral genomes has impeded research progress in PEDV biology and vaccinology. Here, we report the development of reverse genetics systems using two novel infectious full-length cDNA clones of a Korean highly pathogenic-G2b strain, KNU-141112, and its live attenuated vaccine strain, S DEL5/ORF3, in a bacterial artificial chromosome (BAC) under the control of a eukaryotic promoter. Direct transfection of cells with each recombinant BAC clone induced cytopathic effects and produced infectious progeny. The reconstituted viruses, icKNU-141112 and icS DEL5/ORF3, harboring genetic markers, displayed phenotypic and genotypic properties identical to their respective parental viruses. Using the DNA-launched KNU-141112 infectious cDNA clone as a backbone, two types of recombinant viruses were generated. First, we edited the open reading frame 3 (ORF3) gene, as cell-adapted strains lose full-length ORF3, and replaced this region with an enhanced green fluorescent protein (EGFP) gene to generate icPEDV-EGFP. This mutant virus presented parental virus-like growth kinetics and stably retained robust EGFP expression, indicating that ORF3 is dispensable for PEDV replication in cell culture and is a tolerant location for exogeneous gene acceptance. However, the plaque size and syncytia phenotypes of ORF3-null icPEDV-EGFP were larger than those of icKNU-141112 but similar to ORF3-null icS DEL5/ORF3, suggesting a potential role of ORF3 in PEDV cytopathology. Second, we substituted the spike (S) gene with a heterologous S protein, designated S51, from a variant of interest (VOI), which was the most genetically and phylogenetically distant from KNU-141112. The infectious recombinant VOI, named icPEDV-S51, could be recovered, and the rescued virus showed indistinguishable growth characteristics compared to icKNU-141112. Virus cross-neutralization and structural analyses revealed antigenic differences in S between icKNU-141112 and icPEDV-S51, suggesting that genetic and conformational changes mapped within the neutralizing epitopes of S51 could impair the neutralization capacity and cause considerable immune evasion. Collectively, while the established molecular clones afford convenient, versatile platforms for PEDV genome manipulation, allowing for corroborating the molecular basis of viral replication and pathogenesis, they also provide key infrastructural frameworks for developing new vaccines and coronaviral vectors.
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Molecular analysis reveals a distinct subgenogroup of porcine epidemic diarrhea virus in northern Vietnam in 2018-2019. Arch Virol 2022; 167:2337-2346. [PMID: 36036306 PMCID: PMC9421642 DOI: 10.1007/s00705-022-05580-x] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2022] [Accepted: 07/18/2022] [Indexed: 11/13/2022]
Abstract
The spike protein (S) of porcine epidemic diarrhea virus (PEDV), in particular, the C-terminal domain of the S1 subunit (S1-CTD), which contains the conserved CO26K-equivalent (COE) region (aa 499–638), which is recognized by neutralizing antibodies, exhibits a high degree of genetic and antigenic diversity. We analyzed 61 PEDV S1-CTD sequences (630 nt), including 26 from samples collected from seven provinces in northern Vietnam from 2018 to 2019 and 35 other sequences, representing the G1a and 1b, G2a and 2b, and recombinant (G1c) genotypes and vaccines. The majority (73.1%) of the strains (19/26) belonged to subgroup G2b. In a phylogenetic analysis, seven strains were clustered into an independent, distinct subgenogroup named dsG with strong nodal support (98%), separate from both G1a and G1b as well as G2a, 2b, and G1c. Sequence analysis revealed distinct changes (513T>S, 520G>D, 527V>(L/M), 591L>F, 669A>(S/P), and 691V>I) in the COE and S1D regions that were only identified in these Vietnamese strains. This cluster is a new antigenic variant subgroup, and further studies are required to investigate the antigenicity of these variants. The results of this study demonstrated the continuous evolution in the S1 region of Vietnamese PEDV strains, which emphasizes the need for frequent updates of vaccines for effective protection.
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Nguyen Thi TH, Chen CC, Chung WB, Chaung HC, Huang YL, Cheng LT, Ke GM. Antibody Evaluation and Mutations of Antigenic Epitopes in the Spike Protein of the Porcine Epidemic Diarrhea Virus from Pig Farms with Repeated Intentional Exposure (Feedback). Viruses 2022; 14:551. [PMID: 35336958 PMCID: PMC8954129 DOI: 10.3390/v14030551] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2022] [Revised: 02/28/2022] [Accepted: 03/01/2022] [Indexed: 02/01/2023] Open
Abstract
The feedback strategy, or controlled exposure of pig herd to the porcine epidemic diarrhea virus (PEDV), significantly decreased losses during a severe outbreak in late 2013 in Taiwan. However, some pig farms still suffered from recurrent outbreaks. To evaluate the association between antibody titers and clinical manifestations, sera and colostra were analyzed from one pig farm that employed the feedback strategy. Furthermore, spike (S) gene full sequences from six positive samples of two farms with and without using feedback were compared to investigate the evolution of PEDV variants circulating in pig herds. The results in this study showed that high PEDV antibody titers do not correlate with the high rate of protection from PEDV infection. In addition, repeated feedback generated the emergence of PEDV variants with unique substitutions of N537S and Y561H in the COE domain and S769F in the SS6 epitopes. These mutations indicated the pathogenetic evolution of PEDV strains existing in the cycle of the feedback method. A very strict biosecurity practice to block the routes of pathogen transfer should be followed to achieve successful control of PEDV infections in pig herds.
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Affiliation(s)
- Thu Hien Nguyen Thi
- International Degree Program of Animal Vaccine Technology, International College, National Pingtung University of Science and Technology, No.1, Shuefu Road, Neipu, Pingtung 91201, Taiwan;
| | - Chi-Chih Chen
- Research Centre for Animal Biologics, National Pingtung University of Science and Technology, No. 1 Shuefu Road, Neipu, Pingtung 91201, Taiwan; (C.-C.C.); (W.-B.C.); (H.-C.C.); (Y.-L.H.)
| | - Wen-Bin Chung
- Research Centre for Animal Biologics, National Pingtung University of Science and Technology, No. 1 Shuefu Road, Neipu, Pingtung 91201, Taiwan; (C.-C.C.); (W.-B.C.); (H.-C.C.); (Y.-L.H.)
| | - Hso-Chi Chaung
- Research Centre for Animal Biologics, National Pingtung University of Science and Technology, No. 1 Shuefu Road, Neipu, Pingtung 91201, Taiwan; (C.-C.C.); (W.-B.C.); (H.-C.C.); (Y.-L.H.)
| | - Yen-Li Huang
- Research Centre for Animal Biologics, National Pingtung University of Science and Technology, No. 1 Shuefu Road, Neipu, Pingtung 91201, Taiwan; (C.-C.C.); (W.-B.C.); (H.-C.C.); (Y.-L.H.)
| | - Li-Ting Cheng
- Graduate Institute of Animal Vaccine Technology, College of Veterinary Medicine, National Pingtung University of Science and Technology, No. 1 Shuefu Road, Neipu, Pingtung 91201, Taiwan
| | - Guan-Ming Ke
- Research Centre for Animal Biologics, National Pingtung University of Science and Technology, No. 1 Shuefu Road, Neipu, Pingtung 91201, Taiwan; (C.-C.C.); (W.-B.C.); (H.-C.C.); (Y.-L.H.)
- Graduate Institute of Animal Vaccine Technology, College of Veterinary Medicine, National Pingtung University of Science and Technology, No. 1 Shuefu Road, Neipu, Pingtung 91201, Taiwan
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