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Aitkenhead H, Riedel C, Cowieson N, Rümenapf HT, Stuart DI, El Omari K. Structural comparison of typical and atypical E2 pestivirus glycoproteins. Structure 2024; 32:273-281.e4. [PMID: 38176409 DOI: 10.1016/j.str.2023.12.003] [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: 06/07/2023] [Revised: 11/02/2023] [Accepted: 12/07/2023] [Indexed: 01/06/2024]
Abstract
Pestiviruses, within the family Flaviviridae, are economically important viruses of livestock. In recent years, new pestiviruses have been reported in domestic animals and non-cloven-hoofed animals. Among them, atypical porcine pestivirus (APPV) and Norway rat pestivirus (NRPV) have relatively little sequence conservation in their surface glycoprotein E2. Despite E2 being the main target for neutralizing antibodies and necessary for cell attachment and viral fusion, the mechanism of viral entry remains elusive. To gain further insights into the pestivirus E2 mechanism of action and to assess its diversity within the genus, we report X-ray structures of the pestivirus E2 proteins from APPV and NRPV. Despite the highly divergent structures, both are able to dimerize through their C-terminal domain and contain a solvent-exposed β-hairpin reported to be involved in host receptor binding. Functional analysis of this β-hairpin in the context of BVDV revealed its ability to rescue viral infectivity.
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Affiliation(s)
- Hazel Aitkenhead
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK; Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK; Division of Structural Biology, Nuffield Department of Medicine, University of Oxford, The Wellcome Centre for Human Genetics, Oxford, Oxfordshire OX3 7BN, UK
| | - Christiane Riedel
- CIRI-Centre International de Recherche en Infectiologie, University Lyon, Université Claude Bernard Lyon 1, Inserm, U1111, CNRS, UMR5308, ENS Lyon, 46 allée d'Italie, 69007 Lyon, France
| | - Nathan Cowieson
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK
| | - Hans Tillmann Rümenapf
- Institute of Virology, Department of Pathobiology, University of Veterinary Medicine, 1210 Vienna, Austria
| | - David I Stuart
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK; Division of Structural Biology, Nuffield Department of Medicine, University of Oxford, The Wellcome Centre for Human Genetics, Oxford, Oxfordshire OX3 7BN, UK.
| | - Kamel El Omari
- Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE, UK; Research Complex at Harwell, Rutherford Appleton Laboratory, Didcot, Oxfordshire OX11 0FA, UK.
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Newby ML, Allen JD, Crispin M. Influence of glycosylation on the immunogenicity and antigenicity of viral immunogens. Biotechnol Adv 2024; 70:108283. [PMID: 37972669 PMCID: PMC10867814 DOI: 10.1016/j.biotechadv.2023.108283] [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: 02/24/2023] [Revised: 10/04/2023] [Accepted: 11/09/2023] [Indexed: 11/19/2023]
Abstract
A key aspect of successful viral vaccine design is the elicitation of neutralizing antibodies targeting viral attachment and fusion glycoproteins that embellish viral particles. This observation has catalyzed the development of numerous viral glycoprotein mimetics as vaccines. Glycans can dominate the surface of viral glycoproteins and as such, the viral glycome can influence the antigenicity and immunogenicity of a candidate vaccine. In one extreme, glycans can form an integral part of epitopes targeted by neutralizing antibodies and are therefore considered to be an important feature of key immunogens within an immunization regimen. In the other extreme, the existence of peptide and bacterially expressed protein vaccines shows that viral glycosylation can be dispensable in some cases. However, native-like glycosylation can indicate native-like protein folding and the presence of conformational epitopes. Furthermore, going beyond native glycan mimicry, in either occupancy of glycosylation sites or the glycan processing state, may offer opportunities for enhancing the immunogenicity and associated protection elicited by an immunogen. Here, we review key determinants of viral glycosylation and how recombinant immunogens can recapitulate these signatures across a range of enveloped viruses, including HIV-1, Ebola virus, SARS-CoV-2, Influenza and Lassa virus. The emerging understanding of immunogen glycosylation and its control will help guide the development of future vaccines in both recombinant protein- and nucleic acid-based vaccine technologies.
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Affiliation(s)
- Maddy L Newby
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK
| | - Joel D Allen
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
| | - Max Crispin
- School of Biological Sciences, University of Southampton, Southampton, SO17 1BJ, UK.
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Xiang Y, Xu H. Occurrence, formation, and proteins perturbation of disinfection byproducts in indoor air resulting from chlorine disinfection. CHEMOSPHERE 2023; 343:140182. [PMID: 37716567 DOI: 10.1016/j.chemosphere.2023.140182] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2023] [Revised: 09/12/2023] [Accepted: 09/13/2023] [Indexed: 09/18/2023]
Abstract
Increased amounts of chlorine disinfectant have been sprayed to inactivate viruses in the environment since the COVID-19 pandemic, and the health risk from chemicals, especially disinfection byproducts (DBPs), has unintentionally increased. In this study, we characterized the occurrence of haloacetic acids (HAAs) and trihalomethanes (THMs) in indoor air and evaluated their formation potential from typical indoor ingredients. Subsequently, the adverse effect of chloroacetic acid on A549 cells was depicted at the proteomic, transcriptional and silico levels. The results revealed that the total concentrations of HAAs and THMs ranged from 1.46 to 4.20 μg/m3 in ten indoor environments. Both classes of DBPs could be generated during the chlorination of prevalent terpenes by competing reactions, which are associated with the volatile state of indoor ingredients after disinfection. The C-type lectin receptor signaling pathway and cellular senescence were significantly perturbed pathways, which interfered with the development of lung fibrosis. The negative effect was further investigated by molecular docking and transcription, which showed that HAAs can interact with four C-type lectin receptor proteins by hydrogen bonds and inhibit the mRNA expression of related proteins. This study highlights the potential secondary biological risk caused by intensive DBPs generated from chlorination and draws our attention to the potential environmental factors leading to chronic respiratory disease.
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Affiliation(s)
- Yangwei Xiang
- Department of Lung Transplantation and Thoracic Surgery, The First Affiliated Hospital, Zhejiang University School of Medicine, No.79 Qingchun Road, Hangzhou, 310003, Zhejiang Province, China.
| | - Huan Xu
- Institute of Chemical Biology, Shenzhen Bay Laboratory, Shenzhen, 518132, China
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Song Q, Zhao X, Cao C, Duan M, Shao C, Jiang S, Zhou B, Zhou Y, Dong W, Yang Y, Wang X, Song H. Research advances on interferon (IFN) response during BVDV infection. Res Vet Sci 2022; 149:151-158. [DOI: 10.1016/j.rvsc.2022.04.011] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Revised: 03/21/2022] [Accepted: 04/05/2022] [Indexed: 11/28/2022]
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The Molecular Basis for E rns Dimerization in Classical Swine Fever Virus. Viruses 2021; 13:v13112204. [PMID: 34835010 PMCID: PMC8625691 DOI: 10.3390/v13112204] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/20/2021] [Revised: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 11/26/2022] Open
Abstract
The pestivirus classical swine fever virus (CSFV) represents one of the most important pathogens of swine. Its virulence is dependent on the RNase activity of the essential structural glycoprotein Erns that uses an amphipathic helix as a membrane anchor and forms homodimers via disulfide bonds employing cysteine 171. Dimerization is not necessary for CSFV viability but for its virulence. Mutant Erns proteins lacking cysteine 171 are still able to interact transiently as shown in crosslink experiments. Deletion analysis did not reveal the presence of a primary sequence-defined contact surface essential for dimerization, but indicated a general importance of an intact ectodomain for efficient establishment of dimers. Pseudoreverted viruses reisolated in earlier experiments from pigs with mutations Cys171Ser/Ser209Cys exhibited partially restored virulence and restoration of the ability to form Erns homodimers. Dimer formation was also observed for experimentally mutated proteins, in which other amino acids at different positions of the membrane anchor region of Erns were replaced by cysteine. However, with one exception of two very closely located residues, the formation of disulfide-linked dimers was only observed for cysteine residues located at the same position of the helix.
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Mu Y, Tews BA, Luttermann C, Meyers G. Interaction of Pestiviral E1 and E2 Sequences in Dimer Formation and Intracellular Retention. Int J Mol Sci 2021; 22:ijms22147285. [PMID: 34298900 PMCID: PMC8306095 DOI: 10.3390/ijms22147285] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2021] [Revised: 06/29/2021] [Accepted: 07/03/2021] [Indexed: 11/16/2022] Open
Abstract
Pestiviruses contain three envelope proteins: Erns, E1, and E2. Expression of HA-tagged E1 or mutants thereof showed that E1 forms homodimers and -trimers. C123 and, to a lesser extent, C171, affected the oligomerization of E1 with a double mutant C123S/C171S preventing oligomerization completely. E1 also establishes disulfide linked heterodimers with E2, which are crucial for the recovery of infectious viruses. Co-expression analyses with the HA-tagged E1 wt/E1 mutants and E2 wt/E2 mutants demonstrated that C123 in E1 and C295 in E2 are the critical sites for E1/E2 heterodimer formation. Introduction of mutations preventing E1/E2 heterodimer formation into the full-length infectious clone of BVDV CP7 prevented the recovery of infectious viruses, proving that C123 in E1 and C295 in E2 play an essential role in the BVDV life cycle, and further support the conclusion that heterodimer formation is the crucial step. Interestingly, we found that the retention signal of E1 is mandatory for intracellular localization of the heterodimer, so that absence of the E1 retention signal directs the heterodimer to the cell surface even though the E2 retention signal is still present. The covalent linkage between E1 and E2 plays an essential role for this process.
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Affiliation(s)
- Yu Mu
- Institut für Immunologie, Friedrich-Loeffler-Institut, D-17493 Greifswald-Insel Riems, Germany; (Y.M.); (C.L.)
| | - Birke Andrea Tews
- Institut für Infektionsmedizin, Friedrich-Loeffler-Institut, D-17493 Greifswald-Insel Riems, Germany;
| | - Christine Luttermann
- Institut für Immunologie, Friedrich-Loeffler-Institut, D-17493 Greifswald-Insel Riems, Germany; (Y.M.); (C.L.)
| | - Gregor Meyers
- Institut für Immunologie, Friedrich-Loeffler-Institut, D-17493 Greifswald-Insel Riems, Germany; (Y.M.); (C.L.)
- Correspondence: ; Tel.: +49-(0)-3835-171-0
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The E rns Carboxyterminus: Much More Than a Membrane Anchor. Viruses 2021; 13:v13071203. [PMID: 34201636 PMCID: PMC8310223 DOI: 10.3390/v13071203] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2021] [Revised: 06/15/2021] [Accepted: 06/17/2021] [Indexed: 12/12/2022] Open
Abstract
Pestiviruses express the unique essential envelope protein Erns, which exhibits RNase activity, is attached to membranes by a long amphipathic helix, and is partially secreted from infected cells. The RNase activity of Erns is directly connected with pestivirus virulence. Formation of homodimers and secretion of the protein are hypothesized to be important for its role as a virulence factor, which impairs the host's innate immune response to pestivirus infection. The unusual membrane anchor of Erns raises questions with regard to proteolytic processing of the viral polyprotein at the Erns carboxy-terminus. Moreover, the membrane anchor is crucial for establishing the critical equilibrium between retention and secretion and ensures intracellular accumulation of the protein at the site of virus budding so that it is available to serve both as structural component of the virion and factor controlling host immune reactions. In the present manuscript, we summarize published as well as new data on the molecular features of Erns including aspects of its interplay with the other two envelope proteins with a special focus on the biochemistry of the Erns membrane anchor.
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