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Yi W, Wang H, Qin H, Wang Q, Guo R, Wen G, Pan Z. Construction and efficacy of a new live chimeric C-strain vaccine with DIVA characteristics against classical swine fever. Vaccine 2023; 41:2003-2012. [PMID: 36803898 DOI: 10.1016/j.vaccine.2023.02.044] [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: 11/15/2022] [Revised: 02/10/2023] [Accepted: 02/13/2023] [Indexed: 02/21/2023]
Abstract
To develop the new classical swine fever (CSF) vaccine candidate with differentiating infected vaccinated animals (DIVA) characteristics, a chimeric CSF virus (CSFV) was constructed based on an infectious cDNA clone of the CSF vaccine C-strain. The 5'- and 3'-untranslated regions (UTRs) and partial E2 region (residues 690-860) of the C-strain were substituted with the corresponding regions of bovine viral diarrhoea virus (BVDV) to construct the chimeric cDNA clone pC/bUTRs-tE2. The chimeric virus rC/bUTRs-tE2 was generated by several passages of pC/bUTRs-tE2-transfected PK15 cells. Stable growth and genetic properties of rC/bUTRs-tE2 were obtained after 30 serial passages. Compared to parental rC/bUTRs-tE2 (1st passage), two residue mutations (M834K and M979K) located in E2 in rC/bUTRs-tE2 P30 were observed. Compared to the C-strain, rC/bUTRs-tE2 exhibited unchanged cell tropism and decreased plaque-forming ability. Substituting the C-strain UTRs with the BVDV UTRs resulted in significantly increased viral replication in PK15 cells. Compared to CSFV Erns-positive and BVDV tE2-negative antibody responses induced by the CSF vaccine C-strain, immunization of rabbits and piglets with rC/bUTRs-tE2 resulted in serological profiles of CSFV Erns- and BVDV tE2-positive antibodies, which are used to serologically discriminate pigs that are clinically infected and vaccinated. Vaccination of piglets with rC/bUTRs-tE2 conferred complete protection against lethal CSFV challenge. Our results suggest that rC/bUTRs-tE2 is a promising new CSF marker vaccine candidate.
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Affiliation(s)
- Weicheng Yi
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Hao Wang
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China
| | - Huan Qin
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China; Laboratory, Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430015, China
| | - Qin Wang
- World Organisation for Animal Health Reference Laboratory for Classical Swine Fever, China Institute of Veterinary Drug Control, Beijing 100081, China
| | - Rui Guo
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China
| | - Guoyuan Wen
- Key Laboratory of Prevention and Control Agents for Animal Bacteriosis (Ministry of Agriculture and Rural Affairs), Hubei Provincial Key Laboratory of Animal Pathogenic Microbiology, Institute of Animal Husbandry and Veterinary, Hubei Academy of Agricultural Sciences, Wuhan 430064, China
| | - Zishu Pan
- State Key Laboratory of Virology, College of Life Sciences, Wuhan University, Wuhan 430072, China.
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Yi W, Zhu H, Wu Y, Li Q, Lou W, Zhao H, Pan Z. The recombinant Erns and truncated E2-based indirect enzyme-linked immunosorbent assays to distinguishably test specific antibodies against classical swine fever virus and bovine viral diarrhea virus. Virol J 2022; 19:121. [PMID: 35869505 PMCID: PMC9308313 DOI: 10.1186/s12985-022-01851-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2022] [Accepted: 07/06/2022] [Indexed: 02/07/2023] Open
Abstract
Abstract
Background
Classical swine fever (CSF) virus is the causative agent of an economically important, highly contagious disease of pigs. CSFV is genetically and serologically related to bovine viral diarrhea virus (BVDV). BVDV infection in pigs can mimic CSF clinical signs, which cause difficulty in differentiation. Serological test for detection of virus specific antibodies is a valuable tool for diagnosis and surveillance of CSFV and BVDV infections in animals. The aim of this study was to develop the CSFV Erns and BVDV tE2 -based ELISAs to distinguishably test specific antibodies against CSFV and BVDV.
Methods
The CSFV Erns and truncated E2 (tE2, residues 690–865) of BVDV were expressed in E. coli and purified by Ni–NTA affinity chromatography, respectively. Employing Erns or tE2 protein as diagnostic antigen, indirect ELISAs were developed to distinguishably test specific antibodies against CSFV and BVDV. The specificity and sensitivity of ELISAs were evaluated using a panel of virus specific sera of pigs, immunized rabbits and immunized mice. A total 150 clinical serum samples from farm pigs were measured by the developed ELISAs and compared with virus neutralizing test (VNT).
Results
Indirect ELISA was established based on recombinant CSFV Erns or BVDV tE2 protein, respectively. No serological cross-reaction between antibodies against CSFV and BVDV was observed in sera of immunized rabbits, immunized mice or farm pigs by detections of the Erns and tE2 -based ELISAs. Compared to VNT, the CSFV Erns -based ELISA displayed a high sensitivity (93.3%), specificity (92.0%) and agreement rate (92.7%), and the sensitivity, specificity and agreement rate of BVDV tE2 -based ELISA was 92.3%, 95.2% and 94.7%, respectively.
Conclusion
The newly developed ELISAs are highly specific and sensitive and would be valuable tools for serological diagnosis for CSFV and BVDV infections.
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