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Huang YL, Meyer D, Postel A, Tsai KJ, Liu HM, Yang CH, Huang YC, Chang HW, Deng MC, Wang FI, Becher P, Crooke H, Chang CY. Identification of neutralizing epitopes on the D/A domain of the E2 glycoprotein of classical swine fever virus. Virus Res 2023; 336:199209. [PMID: 37633596 PMCID: PMC10485151 DOI: 10.1016/j.virusres.2023.199209] [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: 03/31/2023] [Revised: 08/19/2023] [Accepted: 08/23/2023] [Indexed: 08/28/2023]
Abstract
Classical swine fever virus (CSFV) shares high antigenic homology with other members of the genus Pestivirus. Because several pestivirus species can also infect swine, eliciting cross-reactive antibodies, it is important to define CSFV-specific epitopes for the differential diagnosis of classical swine fever (CSF) by serology. For this purpose, epitope mapping of seven monoclonal antibodies (mAbs), recognizing sites on the D/A domain of glycoprotein E2, was performed using recombinant expressed antigenic domains and mutants of E2, as well as an overlapping peptide library. Three CSFV-specific epitopes, i.e., 780-IEEMGDDFGFGLCPF-794, 810-NGSAFYLVCPIGWTG-824, and 846-REKPF-850, were identified within the D/A domain of E2. Site-directed mutagenesis further confirmed that residues 783-MGD-785, 789-FGLCPF-794, 813-AFYLVCPIGWTG-824, and 846-REK-848 were critical residues in these regions. In addition, a F789S difference within the epitope 780-IEEMGDDFGFGLCPF-794 was responsible for the absence of binding of two mAbs to the E2 protein of the live attenuated CSFV vaccine strain Riems. Structural modeling revealed that, the three epitopes are located near each other, suggesting that they may form a more complex conformational epitope on the D/A domain in vivo. Six of the mAbs neutralized viruses of diverse genotypes, indicating that the target epitopes are involved in virus interaction with cells. The binding of CSFV to cells was significantly reduced after pre-incubation with either truncated E2 proteins comprising the D/A domain or with the CSFV-specific mAbs targeting the domain D/A. These epitopes identified on the D/A domain are important targets for virus neutralization that might be involved in the early steps of CSFV infection. These findings reveal potential candidates for improving the differential diagnosis of pestiviruses by serology.
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Affiliation(s)
- Yu-Liang Huang
- WOAH Reference Laboratory for Classical Swine Fever, Veterinary Research Institute, Ministry of Agriculture, 376 Chung-Cheng Road, Tamsui, New Taipei City 25158, Taiwan
| | - Denise Meyer
- WOAH Reference Laboratory for Classical Swine Fever, Institute of Virology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Alexander Postel
- WOAH Reference Laboratory for Classical Swine Fever, Institute of Virology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Kuo-Jung Tsai
- WOAH Reference Laboratory for Classical Swine Fever, Veterinary Research Institute, Ministry of Agriculture, 376 Chung-Cheng Road, Tamsui, New Taipei City 25158, Taiwan
| | - Hsin-Meng Liu
- WOAH Reference Laboratory for Classical Swine Fever, Veterinary Research Institute, Ministry of Agriculture, 376 Chung-Cheng Road, Tamsui, New Taipei City 25158, Taiwan
| | - Chia-Huei Yang
- WOAH Reference Laboratory for Classical Swine Fever, Veterinary Research Institute, Ministry of Agriculture, 376 Chung-Cheng Road, Tamsui, New Taipei City 25158, Taiwan
| | - Yu-Chun Huang
- WOAH Reference Laboratory for Classical Swine Fever, Veterinary Research Institute, Ministry of Agriculture, 376 Chung-Cheng Road, Tamsui, New Taipei City 25158, Taiwan
| | - Hui-Wen Chang
- School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Ming-Chung Deng
- WOAH Reference Laboratory for Classical Swine Fever, Veterinary Research Institute, Ministry of Agriculture, 376 Chung-Cheng Road, Tamsui, New Taipei City 25158, Taiwan
| | - Fun-In Wang
- School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Paul Becher
- WOAH Reference Laboratory for Classical Swine Fever, Institute of Virology, University of Veterinary Medicine Hannover, 30559 Hannover, Germany
| | - Helen Crooke
- WOAH Reference Laboratory for Classical Swine Fever, Animal and Plant Health Agency, New Haw, Surrey, KT15 3NB, UK.
| | - Chia-Yi Chang
- School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan.
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Han Y, Xie L, Yuan M, Ma Y, Sun H, Sun Y, Li Y, Qiu HJ. Development of a marker vaccine candidate against classical swine fever based on the live attenuated vaccine C-strain. Vet Microbiol 2020; 247:108741. [PMID: 32768202 DOI: 10.1016/j.vetmic.2020.108741] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2020] [Revised: 05/26/2020] [Accepted: 05/26/2020] [Indexed: 12/29/2022]
Abstract
Classical swine fever (CSF) is a highly contagious and economically damaging disease. Classical swine fever virus (CSFV) lapinized vaccine C-strain against CSF worldwide lacks the capacity for the serological differentiation between infected and vaccinated animals (DIVA). To develop a marker C-strain complying with the DIVA principle, we generated and evaluated mutants rHCLV-E2F117A, rHCLV-E2G119A, and rHCLV-E2P122A, which harbor the single amino acid mutation at 117F, 119G or 122P of the monoclonal antibody HQ06-recognized epitope on the E2 glycoprotein in rabbits and pigs. Viral intravenous administration demonstrated that all the mutants retain the phenotype of C-strain in rabbits, including fever response induction and replication in the spleen. Notably, the HQ06-recognized epitope did not react with the antibodies induced by rHCLV-E2P122A in rabbits, in contrast with C-strain and other two mutants. Intramuscular administration of rHCLV-E2P122A in pigs induced anti-CSFV neutralizing antibodies but not antibodies against the HQ06-recognized epitope at 28 days post-inoculation. Collectively, our data demonstrate that rHCLV-E2P122A is a promising marker vaccine candidate against CSF.
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Affiliation(s)
- Yuying Han
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Libao Xie
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Mengqi Yuan
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yuteng Ma
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Huimin Sun
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yuan Sun
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China
| | - Yongfeng Li
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
| | - Hua-Ji Qiu
- State Key Laboratory of Veterinary Biotechnology, Harbin Veterinary Research Institute, Chinese Academy of Agricultural Sciences, Harbin, China.
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Complex Virus-Host Interactions Involved in the Regulation of Classical Swine Fever Virus Replication: A Minireview. Viruses 2017; 9:v9070171. [PMID: 28678154 PMCID: PMC5537663 DOI: 10.3390/v9070171] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2017] [Revised: 06/15/2017] [Accepted: 06/27/2017] [Indexed: 02/06/2023] Open
Abstract
Classical swine fever (CSF), caused by classical swine fever virus (CSFV), is one of the most devastating epizootic diseases of pigs in many countries. Viruses are small intracellular parasites and thus rely on the cellular factors for replication. Fundamental aspects of CSFV-host interactions have been well described, such as factors contributing to viral attachment, modulation of genomic replication and translation, antagonism of innate immunity, and inhibition of cell apoptosis. However, those host factors that participate in the viral entry, assembly, and release largely remain to be elucidated. In this review, we summarize recent progress in the virus-host interactions involved in the life cycle of CSFV and analyze the potential mechanisms of viral entry, assembly, and release. We conclude with future perspectives and highlight areas that require further understanding.
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Structures and Functions of Pestivirus Glycoproteins: Not Simply Surface Matters. Viruses 2015; 7:3506-29. [PMID: 26131960 PMCID: PMC4517112 DOI: 10.3390/v7072783] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2015] [Revised: 06/11/2015] [Accepted: 06/18/2015] [Indexed: 12/21/2022] Open
Abstract
Pestiviruses, which include economically important animal pathogens such as bovine viral diarrhea virus and classical swine fever virus, possess three envelope glycoproteins, namely Erns, E1, and E2. This article discusses the structures and functions of these glycoproteins and their effects on viral pathogenicity in cells in culture and in animal hosts. E2 is the most important structural protein as it interacts with cell surface receptors that determine cell tropism and induces neutralizing antibody and cytotoxic T-lymphocyte responses. All three glycoproteins are involved in virus attachment and entry into target cells. E1-E2 heterodimers are essential for viral entry and infectivity. Erns is unique because it possesses intrinsic ribonuclease (RNase) activity that can inhibit the production of type I interferons and assist in the development of persistent infections. These glycoproteins are localized to the virion surface; however, variations in amino acids and antigenic structures, disulfide bond formation, glycosylation, and RNase activity can ultimately affect the virulence of pestiviruses in animals. Along with mutations that are driven by selection pressure, antigenic differences in glycoproteins influence the efficacy of vaccines and determine the appropriateness of the vaccines that are currently being used in the field.
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Huang YL, Deng MC, Wang FI, Huang CC, Chang CY. The challenges of classical swine fever control: modified live and E2 subunit vaccines. Virus Res 2013; 179:1-11. [PMID: 24211665 DOI: 10.1016/j.virusres.2013.10.025] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2013] [Revised: 10/22/2013] [Accepted: 10/25/2013] [Indexed: 01/15/2023]
Abstract
Classical swine fever (CSF) is an economically important, highly contagious disease of swine worldwide. CSF is caused by classical swine fever virus (CSFV), and domestic pigs and wild boars are its only natural hosts. The two main strategies used to control CSF epidemic are systematic prophylactic vaccination and a non-vaccination stamping-out policy. This review compares the protective efficacy of the routinely used modified live vaccine (MLV) and E2 subunit vaccines and summarizes the factors that influence the efficacy of the vaccines and the challenges that both vaccines face to CSF control. Although MLV provide earlier and more complete protection than E2 subunit vaccines, it has the drawback of not allowing differentiation between infected and vaccinated animals (DIVA). The marker vaccine of E2 protein with companion discriminatory test to detect antibodies against E(rns) allows DIVA and is a promising strategy for future control and eradication of CSF. Maternal derived antibody (MDA) is the critical factor in impairing the efficacy of both MLV and E2 subunit vaccines, so the well-designed vaccination programs of sows and piglets should be considered together. Because of the antigen variation among various genotypes of CSFV, antibodies raised by either MLV or subunit vaccine neutralize genotypically homologous strains better than heterologous ones. However, although this is not a major concern for MLV as the induced immune responses can protect pigs against the challenge of various genotypes of CSFVs, it is critical for E2 subunit vaccines. It is thus necessary to evaluate whether the E2 subunit vaccine can completely protect against the current prevalent strains in the field. An ideal new generation of vaccine should be able to maintain the high protective efficiency of MLV and overcome the problem of antigenic variations while allowing for DIVA.
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Affiliation(s)
- Yu-Liang Huang
- Animal Health Research Institute, Council of Agriculture, 376 Chung-Cheng Road, Tansui, New Taipei City 25158, Taiwan
| | - Ming-Chung Deng
- Animal Health Research Institute, Council of Agriculture, 376 Chung-Cheng Road, Tansui, New Taipei City 25158, Taiwan
| | - Fun-In Wang
- School of Veterinary Medicine, National Taiwan University, No. 1, Section 4, Roosevelt Road, Taipei 10617, Taiwan
| | - Chin-Cheng Huang
- Pingtung Agriculture Biotechnology Park, Council of Agriculture, No. 1 Shennong Road, Dehe Village, Changjhih Township, Pingtung County 90846, Taiwan
| | - Chia-Yi Chang
- Animal Health Research Institute, Council of Agriculture, 376 Chung-Cheng Road, Tansui, New Taipei City 25158, Taiwan.
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Jelsma H, Loeffen WLA, van Beuningen A, van Rijn PA. Preliminary mapping of non-conserved epitopes on envelope glycoprotein E2 of Bovine viral diarrhea virus type 1 and 2. Vet Microbiol 2013; 166:195-9. [PMID: 23838147 DOI: 10.1016/j.vetmic.2013.06.008] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2012] [Revised: 05/23/2013] [Accepted: 06/10/2013] [Indexed: 11/25/2022]
Abstract
Bovine viral diarrhea virus (BVDV) belongs together with Classical swine fever virus (CSFV) and Border disease virus (BDV) to the genus Pestivirus in the Flaviviridae family. BVDV has been subdivided into two different species, BVDV1 and BVDV2 based on phylogenetic analysis. Subsequent characterization of both strains revealed major antigenic differences. Because the envelope glycoprotein E2 is the most immunodominant protein for all pestiviruses, the present study focused on epitope mapping by constructing chimeric BVDV type 1 and 2 E2 genes in expression plasmids. These plasmids with chimeric E2-genes were transfected in SK6 cells and transient expression was studied by immunostaining with a panel of MAbs specific for E2 of BVDV1 or BVDV2, resulting in the localization of type-specific antigenic domains at similar regions. These results indicate that E2 glycoproteins of both BVDV types exhibit a comparable antigenic structure, but with type specific epitopes. In addition, the antigenic resemblance with envelope glycoprotein E2 of Classical swine fever virus is discussed.
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Affiliation(s)
- H Jelsma
- Central Veterinary Institute of Wageningen UR, P.O. Box 65, 8200 AB Lelystad, The Netherlands.
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Identification of conformational epitopes and antigen-specific residues at the D/A domains and the extramembrane C-terminal region of E2 glycoprotein of classical swine fever virus. Virus Res 2012; 168:56-63. [PMID: 22727685 DOI: 10.1016/j.virusres.2012.06.013] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2012] [Revised: 06/10/2012] [Accepted: 06/12/2012] [Indexed: 11/20/2022]
Abstract
Envelope glycoprotein E2 of classical swine fever virus (CSFV) is the major antigen that induces neutralizing antibodies in infected pigs. Previous studies revealed that both conformation-dependent and linear epitopes are most present within domains B/C/D/A in the N-terminal half of E2. However, studies of antigenicity beyond the B/C domains remain limited. This study revealed that conformational epitopes were present on the D/A domains as well as the proximal C-terminal of E2, since the mutation of cysteine abrogated their bindings to monoclonal antibodies (mAbs). The residue R845 at domain A and E902 at the C-terminal region were critical for specific binding to mAbs, further supporting the presence of antigenic determinants on these regions. Substitutions of cysteines in domains D/A not only abrogated the binding to mAbs directed to D/A, but also affected the binding of the downstream C-terminal region to its specific mAbs, suggesting a close interaction between the two conformational epitopes. Mutations on the five proximal cysteines at positions 869, 877, 893, 896 and 930 in the C-terminal region only affected the binding to its specific mAbs binding sites. In addition, mutation on the three distal C-terminal cysteines at positions 945, 966, and 983 resulted in loss of E2 homodimerization. This study demonstrates new antigenic epitopes on D/A domains and C-terminal of E2 that have not been reported before, and that the nine cysteines in the C-terminal function differently in either maintaining the antigenic structure or in intermolecular dimerization of E2.
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Leifer I, Blome S, Blohm U, König P, Küster H, Lange B, Beer M. Characterization of C-strain "Riems" TAV-epitope escape variants obtained through selective antibody pressure in cell culture. Vet Res 2012; 43:33. [PMID: 22515281 PMCID: PMC3463427 DOI: 10.1186/1297-9716-43-33] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2011] [Accepted: 02/23/2012] [Indexed: 02/02/2023] Open
Abstract
Classical swine fever virus (CSFV) C-strain “Riems” escape variants generated under selective antibody pressure with monoclonal antibodies and a peptide-specific antiserum in cell culture were investigated. Candidates with up to three amino acid exchanges in the immunodominant and highly conserved linear TAV-epitope of the E2-glycoprotein, and additional mutations in the envelope proteins ERNS and E1, were characterized both in vitro and in vivo. It was further demonstrated, that intramuscular immunization of weaner pigs with variants selected after a series of passages elicited full protection against lethal CSFV challenge infection. These novel CSFV C-strain variants with exchanges in the TAV-epitope present potential marker vaccine candidates. The DIVA (differentiating infected from vaccinated animals) principle was tested for those variants using commercially available E2 antibody detection ELISA. Moreover, direct virus differentiation is possible using a real-time RT-PCR system specific for the new C-strain virus escape variants or using differential immunofluorescence staining.
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Affiliation(s)
- Immanuel Leifer
- Institute of Diagnostic Virology, Friedrich-Loeffler-Institut, Südufer 10, 17493, Greifswald-Insel Riems, Germany.
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Chang CY, Huang CC, Deng MC, Huang YL, Lin YJ, Liu HM, Lin YL, Wang FI. Antigenic mimicking with cysteine-based cyclized peptides reveals a previously unknown antigenic determinant on E2 glycoprotein of classical swine fever virus. Virus Res 2012; 163:190-6. [DOI: 10.1016/j.virusres.2011.09.019] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2011] [Revised: 09/10/2011] [Accepted: 09/12/2011] [Indexed: 10/17/2022]
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Chang CY, Huang CC, Lin YJ, Deng MC, Tsai CH, Chang WM, Wang FI. Identification of antigen-specific residues on E2 glycoprotein of classical swine fever virus. Virus Res 2010; 152:65-72. [PMID: 20558217 DOI: 10.1016/j.virusres.2010.06.005] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2010] [Revised: 06/02/2010] [Accepted: 06/07/2010] [Indexed: 10/19/2022]
Abstract
Envelope glycoprotein E2 of classical swine fever virus (CSFV) is the major antigen that induces neutralizing antibodies in infected pigs. Our previous study revealed that N-terminal 90 residues (domains B/C) of E2 play key roles in differentiating vaccine strain LPC/AHRI (subgroup 1.1) from the two field strains TD/96/TWN (subgroup 2.1) and 94.4/IL/94/TWN (subgroup 3.4) (Chang et al., 2010). This study further analyzed the reaction patterns between monoclonal antibodies (mAbs) and expressed hybrid N-terminal of E2 of the above-mentioned viruses, revealing that mAbs T33 and C2, mAbs V8 and T23, and mAbs L7 and L150 required binding sites specifically at residues 690-714 in domain B, residues 715-740 in domain C, and residues 741-765 in domain C, respectively. Site-directed mutagenesis further demonstrated that residues (713)E and (729)D were critical for antigenic specificity of field strain (94.4/IL/94/TWN), while residues (705)D and (761)K were specific for vaccine strain (LPC/AHRI). These specific residues likely mediated in determining the topography of mAb binding sites of E2 to allow for differentiation between strains based on the premise that the structural integrity of the conformational epitope is maintained.
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Affiliation(s)
- Chia-Yi Chang
- Animal Health Research Institute, Council of Agriculture, 376 Chung-Cheng Road, Tansui, Taipei, Taiwan
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