1
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Sives S, Keep S, Bickerton E, Vervelde L. Revealing Novel-Strain-Specific and Shared Epitopes of Infectious Bronchitis Virus Spike Glycoprotein Using Chemical Linkage of Peptides onto Scaffolds Precision Epitope Mapping. Viruses 2023; 15:2279. [PMID: 38005955 PMCID: PMC10675791 DOI: 10.3390/v15112279] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2023] [Revised: 11/16/2023] [Accepted: 11/17/2023] [Indexed: 11/26/2023] Open
Abstract
The avian coronavirus, infectious bronchitis virus (IBV), is an economically important infectious disease affecting chickens, with a diverse range of serotypes found globally. The major surface protein, spike (S), has high diversity between serotypes, and amino acid differences in the S1 sub-unit are thought to be responsible for poor cross-protection afforded by vaccination. Here, we attempt to address this, by using epitope mapping technology to identify shared and serotype-specific immunogenic epitopes of the S glycoprotein of three major circulating strains of IBV, M41, QX, and 4/91, via CLIPS peptide arrays based on peptides from the S1 sub-units. The arrays were screened with sera from chickens immunised with recombinant IBV, based on Beau-R backbone expressing heterologous S, generated in two independent vaccination/challenge trials. The screening of sera from rIBV vaccination experiments led to the identification of 52 immunogenic epitopes on the S1 of M41, QX, and 4/91. The epitopes were assigned into six overlapping epitope binding regions. Based on accessibility and location in the hypervariable regions of S, three sequences, 25YVYYYQSAFRPPNGWHLQGGAYAVVNSTN54, 67TVGVIKDVYNQSVASI82, and 83AMTVPPAGMSWSVS96, were selected for further investigation, and synthetic peptide mimics were recognised by polyclonal sera. These epitopes may have the potential to contribute towards a broader cross-protective IBV vaccine.
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Affiliation(s)
- Samantha Sives
- Division of Immunology, The Roslin Institute & R(D)SVS, University of Edinburgh, Easter Bush, Edinburgh EH25 9RG, UK;
| | - Sarah Keep
- The Pirbright Institute, Ash Road, Woking GU24 0NF, UK (E.B.)
| | - Erica Bickerton
- The Pirbright Institute, Ash Road, Woking GU24 0NF, UK (E.B.)
| | - Lonneke Vervelde
- Division of Immunology, The Roslin Institute & R(D)SVS, University of Edinburgh, Easter Bush, Edinburgh EH25 9RG, UK;
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2
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Jiang Y, Xue M, Tang M, Zhang D, Yu Y, Zhou S. Adaptation of the infectious bronchitis virus H120 vaccine strain to Vero cell lines. Vet Microbiol 2023; 280:109709. [PMID: 36870205 DOI: 10.1016/j.vetmic.2023.109709] [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: 11/17/2022] [Revised: 02/22/2023] [Accepted: 02/24/2023] [Indexed: 02/27/2023]
Abstract
Infectious bronchitis virus (IBV) has restricted cell and tissue tropism. IBVs, except the Beaudette strain, can infect and replicate in chicken embryos, primary chicken embryo kidneys, and primary chicken kidney cells, only. The limited viral cell tropism of IBV substantially hinders in vitro cell-based research on pathogenic mechanisms and vaccine development. Herein, the parental H120 vaccine strain was serially passaged for five generations in chicken embryos, 20 passages in CK cells and 80 passages in Vero cells. This passaging yielded a Vero cell-adapted strain designated HV80. To further understand viral evolution, serial assessments of infection, replication, and transmission in Vero cells were performed for the viruses obtained every tenth passage. The ability to form syncytia and the replication efficiency significantly after the 50th passage (strain HV50). HV80 also displayed tropism extension to DF-1, BHK-21, HEK-293 T, and HeLa cells. Whole genome sequencing of viruses from every tenth generation revealed a total of 19 amino acid point mutations in the viral genome by passage 80, nine of which occurred in the S gene. The second furin cleavage site appeared in viral evolution and may be associated with cell tropism extension of HV80.
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Affiliation(s)
- Yi Jiang
- Poultry Institute, Chinese Academy of Agricultural Sciences, 225125, China; Animal Infectious Disease Laboratory, College of Veterinary Medicine, Yangzhou University, 225009, China
| | - Mei Xue
- Poultry Institute, Chinese Academy of Agricultural Sciences, 225125, China; College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China
| | - Mengjun Tang
- Poultry Institute, Chinese Academy of Agricultural Sciences, 225125, China; College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China
| | - Di Zhang
- Poultry Institute, Chinese Academy of Agricultural Sciences, 225125, China; College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China
| | - Yan Yu
- Poultry Institute, Chinese Academy of Agricultural Sciences, 225125, China; College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China
| | - Sheng Zhou
- College of Veterinary Medicine, Qingdao Agricultural University, Qingdao 266109, China.
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3
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Ting X, Xiang C, Liu DX, Chen R. Establishment and Cross-Protection Efficacy of a Recombinant Avian Gammacoronavirus Infectious Bronchitis Virus Harboring a Chimeric S1 Subunit. Front Microbiol 2022; 13:897560. [PMID: 35935229 PMCID: PMC9354458 DOI: 10.3389/fmicb.2022.897560] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2022] [Accepted: 06/16/2022] [Indexed: 11/13/2022] Open
Abstract
Infectious bronchitis virus (IBV) is a gammacoronavirus that causes a highly contagious disease in chickens and seriously endangers the poultry industry. A diversity of serotypes and genotypes of IBV have been identified worldwide, and the currently available vaccines do not cross-protect. In the present study, an efficient reverse genetics technology based on Beaudette-p65 has been used to construct a recombinant IBV, rIBV-Beaudette-KC(S1), by replacing the nucleotides 21,704–22,411 with the corresponding sequence from an isolate of QX-like genotype KC strain. Continuous passage of this recombinant virus in chicken embryos resulted in the accumulation of two point mutations (G21556C and C22077T) in the S1 region. Further studies showed that the T248S (G21556C) substitution may be essential for the adaptation of the recombinant virus to cell culture. Immunization of chicks with the recombinant IBV elicited strong antibody responses and showed high cross-protection against challenges with virulent M41 and a QX-like genotype IBV. This study reveals the potential of developing rIBV-Beau-KC(S1) as a cell-based vaccine with a broad protective immunity against two different genotypes of IBV.
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Affiliation(s)
- Xiong Ting
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Chengwei Xiang
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
| | - Ding Xiang Liu
- Zhaoqing Branch of Guangdong Laboratory of Lingnan Modern Agricultural Science and Technology, Zhaoqing, China
- Integrative Microbiology Research Centre, South China Agricultural University, Guangzhou, China
- Ding Xiang Liu ;
| | - Ruiai Chen
- College of Veterinary Medicine, South China Agricultural University, Guangzhou, China
- Zhaoqing Branch of Guangdong Laboratory of Lingnan Modern Agricultural Science and Technology, Zhaoqing, China
- *Correspondence: Ruiai Chen
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4
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Identification of Amino Acids within Nonstructural Proteins 10 and 14 of the Avian Coronavirus Infectious Bronchitis Virus That Result in Attenuation In Vivo and In Ovo. J Virol 2022; 96:e0205921. [PMID: 35044208 PMCID: PMC8941869 DOI: 10.1128/jvi.02059-21] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
The Gammacoronavirus infectious bronchitis virus (IBV) is a highly contagious global pathogen prevalent in all types of poultry flocks. IBV is responsible for economic losses and welfare issues in domestic poultry, resulting in a significant risk to food security. IBV vaccines are currently generated by serial passage of virulent IBV field isolates through embryonated hens' eggs. The different patterns of genomic variation accumulated during this process means that the exact mechanism of attenuation is unknown and presents a risk of reversion to virulence. Additionally, the passaging process adapts the virus to replicate in chicken embryos, increasing embryo lethality. Vaccines produced in this manner are therefore unsuitable for in ovo application. We have developed a reverse genetics system, based on the pathogenic IBV strain M41, to identify genes which can be targeted for rational attenuation. During the development of this reverse genetics system, we identified four amino acids, located in nonstructural proteins (nsps) 10, 14, 15, and 16, which resulted in attenuation both in vivo and in ovo. Further investigation highlighted a role of amino acid changes, Pro85Leu in nsp 10 and Val393Leu in nsp 14, in the attenuated in vivo phenotype observed. This study provides evidence that mutations in nsps offer a promising mechanism for the development of rationally attenuated live vaccines against IBV, which have the potential for in ovo application. IMPORTANCE The Gammacoronavirus infectious bronchitis virus (IBV) is the etiological agent of infectious bronchitis, an acute, highly contagious, economically important disease of poultry. Vaccination is achieved using a mixture of live attenuated vaccines for young chicks and inactivated vaccines as boosters for laying hens. Live attenuated vaccines are generated through serial passage in embryonated hens' eggs, an empirical process which achieves attenuation but retains immunogenicity. However, these vaccines have a risk of reversion to virulence, and they are lethal to the embryo. In this study, we identified amino acids in the replicase gene which attenuated IBV strain M41, both in vivo and in ovo. Stability assays indicate that the attenuating amino acids are stable and unlikely to revert. The data in this study provide evidence that specific modifications in the replicase gene offer a promising direction for IBV live attenuated vaccine development, with the potential for in ovo application.
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5
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Yin L, Wu Q, Lin Z, Qian K, Shao H, Wan Z, Liu Y, Ye J, Qin A. A Peptide-Based Enzyme-Linked Immunosorbent Assay for Detecting Antibodies Against Avian Infectious Bronchitis Virus. Front Vet Sci 2021; 7:619601. [PMID: 33553284 PMCID: PMC7859331 DOI: 10.3389/fvets.2020.619601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Accepted: 12/16/2020] [Indexed: 01/21/2023] Open
Abstract
Infectious bronchitis virus (IBV) causes substantial loss to the poultry industry despite extensive vaccination. Assessing the antibody response is important for the development and evaluation of effective vaccines. We have developed an enzyme-linked immunosorbent assay (ELISA) for the detection of IBV-specific antibodies, using a synthetic peptide based on a conserved sequence in the IBV spike protein. This peptide-based ELISA (pELISA) specifically detects antibodies to different genotypes of IBV but not antibodies against other common chicken viruses. This assay could detect IBV-specific antibody response on as early as day 7 postinfection. In the testing with field serum samples collected from chickens administered with IBV vaccines, the sensitivity, specificity, and accuracy of pELISA were 98.30, 94.12, and 98.8%, respectively, relative to indirect immunofluorescence assay. Our data demonstrate that the pELISA is of value for the detection of IBV antibody and the evaluation of IBV vaccines.
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Affiliation(s)
- Liping Yin
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,JiangsuLihua Animal Husbandry Co., Ltd, Changzhou, China
| | - Qi Wu
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Zhixian Lin
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China
| | - Kun Qian
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.,The International Joint Laboratory for Cooperation in Agriculture and Agricultural Product Safety, Ministry of Education, Yangzhou University, Yangzhou, China
| | - Hongxia Shao
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.,The International Joint Laboratory for Cooperation in Agriculture and Agricultural Product Safety, Ministry of Education, Yangzhou University, Yangzhou, China
| | - Zhimin Wan
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.,The International Joint Laboratory for Cooperation in Agriculture and Agricultural Product Safety, Ministry of Education, Yangzhou University, Yangzhou, China
| | - Yuelong Liu
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,JiangsuLihua Animal Husbandry Co., Ltd, Changzhou, China
| | - Jianqiang Ye
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.,The International Joint Laboratory for Cooperation in Agriculture and Agricultural Product Safety, Ministry of Education, Yangzhou University, Yangzhou, China
| | - Aijian Qin
- Key Laboratory of Avian Preventive Medicine, Ministry of Education, Yangzhou University, Yangzhou, China.,Jiangsu Co-innovation Center for Prevention and Control of Important Animal Infectious Diseases and Zoonoses, Yangzhou, China.,The International Joint Laboratory for Cooperation in Agriculture and Agricultural Product Safety, Ministry of Education, Yangzhou University, Yangzhou, China
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6
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Jiang Y, Gao M, Cheng X, Yu Y, Shen X, Li J, Zhou S. The V617I Substitution in Avian Coronavirus IBV Spike Protein Plays a Crucial Role in Adaptation to Primary Chicken Kidney Cells. Front Microbiol 2020; 11:604335. [PMID: 33391226 PMCID: PMC7775488 DOI: 10.3389/fmicb.2020.604335] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2020] [Accepted: 11/27/2020] [Indexed: 12/30/2022] Open
Abstract
The naturally isolated avian coronavirus infectious bronchitis virus (IBV) generally cannot replicate in chicken kidney (CK) cells. To explore the molecular mechanism of IBV adapting to CK cells, a series of recombinant viruses were constructed by chimerizing the S genes of CK cell-adapted strain H120 and non-adapted strain IBYZ. The results showed that the S2 subunit determines the difference in cell tropism of the two strains. After comparing the amino acid sequences of S protein of CK cell-adapted strain YZ120, with its parental strain IBYZ, three amino acid substitutions, A138V, L581F, and V617I, were identified. Using YZ120 as the backbone, one or more of the above-mentioned substitutions were eliminated to verify the correlation between these sites and CK cell tropism. The results showed that the CK cell tropism of the YZ120 strain depends on the V617I substitution, the change of L581F promoted the adaptation in CK cells, and the change at 138 position was not directly related to the CK cell tropism. Further validation experiments also showed that V617I had a decisive role in the adaptation of IBV to CK cells, but other areas of the virus genome also affected the replication efficiency of the virus in CK cells.
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Affiliation(s)
- Yi Jiang
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Jiangsu Institute of Poultry Science (CAAS), Yangzhou, China.,Laboratory of Animal Infectious Disease, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Mingyan Gao
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Jiangsu Institute of Poultry Science (CAAS), Yangzhou, China
| | - Xu Cheng
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Jiangsu Institute of Poultry Science (CAAS), Yangzhou, China
| | - Yan Yu
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Jiangsu Institute of Poultry Science (CAAS), Yangzhou, China
| | - Xinyue Shen
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Jiangsu Institute of Poultry Science (CAAS), Yangzhou, China.,Laboratory of Animal Infectious Disease, College of Veterinary Medicine, Yangzhou University, Yangzhou, China
| | - Jianmei Li
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Jiangsu Institute of Poultry Science (CAAS), Yangzhou, China
| | - Sheng Zhou
- Poultry Institute, Chinese Academy of Agricultural Sciences, Yangzhou, China.,Jiangsu Institute of Poultry Science (CAAS), Yangzhou, China
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7
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Stevenson-Leggett P, Keep S, Bickerton E. Treatment with Exogenous Trypsin Expands In Vitro Cellular Tropism of the Avian Coronavirus Infectious Bronchitis Virus. Viruses 2020; 12:E1102. [PMID: 33003350 PMCID: PMC7600076 DOI: 10.3390/v12101102] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 09/23/2020] [Accepted: 09/28/2020] [Indexed: 12/27/2022] Open
Abstract
The Gammacoronavirus infectious bronchitis virus (IBV) causes a highly contagious and economically important respiratory disease in poultry. In the laboratory, most IBV strains are restricted to replication in ex vivo organ cultures or in ovo and do not replicate in cell culture, making the study of their basic virology difficult. Entry of IBV into cells is facilitated by the large glycoprotein on the surface of the virion, the spike (S) protein, comprised of S1 and S2 subunits. Previous research showed that the S2' cleavage site is responsible for the extended tropism of the IBV Beaudette strain. This study aims to investigate whether protease treatment can extend the tropism of other IBV strains. Here we demonstrate that the addition of exogenous trypsin during IBV propagation in cell culture results in significantly increased viral titres. Using a panel of IBV strains, exhibiting varied tropisms, the effects of spike cleavage on entry and replication were assessed by serial passage cell culture in the presence of trypsin. Replication could be maintained over serial passages, indicating that the addition of exogenous protease is sufficient to overcome the barrier to infection. Mutations were identified in both S1 and S2 subunits following serial passage in cell culture. This work provides a proof of concept that exogenous proteases can remove the barrier to IBV replication in otherwise non-permissive cells, providing a platform for further study of elusive field strains and enabling sustainable vaccine production in vitro.
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Affiliation(s)
| | | | - Erica Bickerton
- The Pirbright Institute, Ash Road, Woking, Surrey GU24 0NF, UK; (P.S.-L.); (S.K.)
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8
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The Characterization of chIFITMs in Avian Coronavirus Infection In Vivo, Ex Vivo and In Vitro. Genes (Basel) 2020; 11:genes11080918. [PMID: 32785186 PMCID: PMC7464837 DOI: 10.3390/genes11080918] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2020] [Revised: 08/06/2020] [Accepted: 08/07/2020] [Indexed: 01/11/2023] Open
Abstract
The coronaviruses are a large family of enveloped RNA viruses that commonly cause gastrointestinal or respiratory illnesses in the infected host. Avian coronavirus infectious bronchitis virus (IBV) is a highly contagious respiratory pathogen of chickens that can affect the kidneys and reproductive systems resulting in bird mortality and decreased reproductivity. The interferon-inducible transmembrane (IFITM) proteins are activated in response to viral infections and represent a class of cellular restriction factors that restrict the replication of many viral pathogens. Here, we characterize the relative mRNA expression of the chicken IFITM genes in response to IBV infection, in vivo, ex vivo and in vitro using the pathogenic M41-CK strain, the nephropathogenic QX strain and the nonpathogenic Beaudette strain. In vivo we demonstrate a significant upregulation of chIFITM1, 2, 3 and 5 in M41-CK- and QX-infected trachea two days post-infection. In vitro infection with Beaudette, M41-CK and QX results in a significant upregulation of chIFITM1, 2 and 3 at 24 h post-infection. We confirmed a differential innate response following infection with distinct IBV strains and believe that our data provide new insights into the possible role of chIFITMs in early IBV infection.
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9
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Abstract
Since the end of 2019, the global COVID-19 outbreak has once again made coronaviruses a hot topic. Vaccines are hoped to be an effective way to stop the spread of the virus. However, there are no clinically approved vaccines available for coronavirus infections. Reverse genetics technology can realize the operation of RNA virus genomes at the DNA level and provide new ideas and strategies for the development of new vaccines. In this review, we systematically describe the role of reverse genetics technology in studying the effects of coronavirus proteins on viral virulence and innate immunity, cell and tissue tropism and antiviral drug screening. An efficient reverse genetics platform is useful for obtaining the ideal attenuated strain to prepare an attenuated live vaccine.
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10
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Keep S, Sives S, Stevenson-Leggett P, Britton P, Vervelde L, Bickerton E. Limited Cross-Protection against Infectious Bronchitis Provided by Recombinant Infectious Bronchitis Viruses Expressing Heterologous Spike Glycoproteins. Vaccines (Basel) 2020; 8:E330. [PMID: 32580371 PMCID: PMC7350270 DOI: 10.3390/vaccines8020330] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2020] [Revised: 06/19/2020] [Accepted: 06/21/2020] [Indexed: 12/19/2022] Open
Abstract
Gammacoronavirus infectious bronchitis virus (IBV) causes an economically important respiratory disease of poultry. Protective immunity is associated with the major structural protein, spike (S) glycoprotein, which induces neutralising antibodies and defines the serotype. Cross-protective immunity between serotypes is limited and can be difficult to predict. In this study, the ability of two recombinant IBV vaccine candidates, BeauR-M41(S) and BeauR-4/91(S), to induce cross-protection against a third serotype, QX, was assessed. Both rIBVs are genetically based on the Beaudette genome with only the S gene derived from either M41 or 4/91, two unrelated serotypes. The use of these rIBVs allowed for the assessment of the potential of M41 and 4/91 S glycoproteins to induce cross-protective immunity against a heterologous QX challenge. The impact of the order of vaccination was also assessed. Homologous primary and secondary vaccination with BeauR-M41(S) or BeauR-4/91(S) resulted in a significant reduction of infectious QX load in the trachea at four days post-challenge, whereas heterologous primary and secondary vaccination with BeauR-M41(S) and BeauR-4/91(S) reduced viral RNA load in the conjunctiva-associated lymphoid tissue (CALT). Both homologous and heterologous vaccination regimes reduced clinical signs and birds recovered more rapidly as compared with an unvaccinated/challenge control group. Despite both rIBV BeauR-M41(S) and BeauR-4/91(S) displaying limited replication in vivo, serum titres in these vaccinated groups were higher as compared with the unvaccinated/challenge control group. This suggests that vaccination with rIBV primed the birds for a boosted humoral response to heterologous QX challenge. Collectively, vaccination with the rIBV elicited limited protection against challenge, with failure to protect against tracheal ciliostasis, clinical manifestations, and viral replication. The use of a less attenuated recombinant vector that replicates throughout the respiratory tract could be required to elicit a stronger and prolonged protective immune response.
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Affiliation(s)
- Sarah Keep
- The Pirbright Institute, Pirbright, Surrey GU24 0NF, UK; (S.K.); (P.S.-L.); (P.B.)
| | - Samantha Sives
- Division of Infection and Immunity, The Roslin Institute and Royal (Dick), School of Veterinary Studies, University of Edinburgh, Easter Bush EH25 9RG, UK; (S.S.); (L.V.)
| | | | - Paul Britton
- The Pirbright Institute, Pirbright, Surrey GU24 0NF, UK; (S.K.); (P.S.-L.); (P.B.)
| | - Lonneke Vervelde
- Division of Infection and Immunity, The Roslin Institute and Royal (Dick), School of Veterinary Studies, University of Edinburgh, Easter Bush EH25 9RG, UK; (S.S.); (L.V.)
| | - Erica Bickerton
- The Pirbright Institute, Pirbright, Surrey GU24 0NF, UK; (S.K.); (P.S.-L.); (P.B.)
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11
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Recombinant infectious bronchitis coronavirus H120 with the spike protein S1 gene of the nephropathogenic IBYZ strain remains attenuated but induces protective immunity. Vaccine 2020; 38:3157-3168. [PMID: 32057575 PMCID: PMC7115396 DOI: 10.1016/j.vaccine.2020.01.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 12/28/2019] [Accepted: 01/02/2020] [Indexed: 12/26/2022]
Abstract
Infectious bronchitis (IB) is a highly infectious viral disease responsible for major economic losses in the poultry industry. A reverse genetic vaccine is a safe, rapid, and effective method of achieving IB prevention and control. In this study, we constructed the recombinant strain, rH120-S1/YZ, using a reverse genetic system, based on the backbone of the H120 vaccine strain, with the S1 gene replaced with that of the QX-like nephropathogenic strain, ck/CH/IBYZ/2011, isolated in China. The results of dwarf chicken embryos, growth kinetics, and viral titration in the embryos demonstrated that the biological characteristics of the recombinant virus remained unchanged. Like the rH120-infected group and in contrast to the rIBYZ-infected group, no mortality, clinical signs, or lesions were observed in the lungs or kidneys of young chickens inoculated with rH120-S1/YZ. The viral loads in various tissues, cloacal, and oral swabs was lower in most types of samples, indicating that the rH120-S1/YZ strain was highly safe in chicks. Compared to rH120 vaccination group, when the efficacy of this strain was evaluated against the QX-like IBV strain, better protection, with 100% survival rate and no disease symptom or gross lesion was observed in the chickens vaccinated with rH120-S1/YZ. Increased levels of IBV-specific antibodies were detected in the serum of the rH120-S1/YZ-vaccinated animals 14 days post-vaccination. Collectively, our results suggest that the recombinant strain, rH120-S1/YZ, may represent a promising vaccine candidate against QX-like IBVs.
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12
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The S2 Subunit of QX-type Infectious Bronchitis Coronavirus Spike Protein Is an Essential Determinant of Neurotropism. Viruses 2019; 11:v11100972. [PMID: 31652591 PMCID: PMC6832359 DOI: 10.3390/v11100972] [Citation(s) in RCA: 41] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2019] [Revised: 10/17/2019] [Accepted: 10/21/2019] [Indexed: 01/23/2023] Open
Abstract
Some coronaviruses (CoVs) have an extra furin cleavage site (RRKR/S, furin-S2′ site) upstream of the fusion peptide in the spike protein, which plays roles in virion adsorption and fusion. Mutation of the S2′ site of QX genotype (QX-type) infectious bronchitis virus (IBV) spike protein (S) in a recombinant virus background results in higher pathogenicity, pronounced neural symptoms and neurotropism when compared with conditions in wild-type IBV (WT-IBV) infected chickens. In this study, we present evidence suggesting that recombinant IBV with a mutant S2′ site (furin-S2′ site) leads to higher mortality. Infection with mutant IBV induces severe encephalitis and breaks the blood–brain barrier. The results of a neutralization test and immunoprotection experiment show that an original serum and vaccine can still provide effective protection in vivo and in vitro. This is the first demonstration of IBV-induced neural symptoms in chickens with encephalitis and the furin-S2′ site as a determinant of neurotropism.
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