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Generation of a Soluble African Horse Sickness Virus VP7 Protein Capable of Forming Core-like Particles. Viruses 2022; 14:v14081624. [PMID: 35893692 PMCID: PMC9331310 DOI: 10.3390/v14081624] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2022] [Revised: 07/12/2022] [Accepted: 07/21/2022] [Indexed: 02/06/2023] Open
Abstract
A unique characteristic of the African horse sickness virus (AHSV) major core protein VP7 is that it is highly insoluble, and spontaneously forms crystalline particles in AHSV-infected cells and when expressed in vitro. The aggregation of AHSV VP7 into these crystals presents many problems in AHSV vaccine development, and it is unclear whether VP7 aggregation affects AHSV assembly or contributes to AHSV pathogenesis. Here, we set out to abolish VP7 self-assembly by targeting candidate amino acid regions on the surface of the VP7 trimer via site-directed mutagenesis. It was found that the substitution of seven amino acids resulted in the complete disruption of AHSV VP7 self-assembly, which abolished the formation of VP7 crystalline particles and converted VP7 to a fully soluble protein still capable of interacting with VP3 to form core-like particles. This work provides further insight into the formation of AHSV VP7 crystalline particles and the successful development of AHSV vaccines. It also paves the way for future research by drawing comparisons with similar viral phenomena observed in human virology.
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Fearon SH, Dennis SJ, Hitzeroth II, Rybicki EP, Meyers AE. Plant expression systems as an economical alternative for the production of iELISA coating antigen AHSV VP7. N Biotechnol 2022; 68:48-56. [DOI: 10.1016/j.nbt.2022.01.009] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/06/2020] [Revised: 12/28/2021] [Accepted: 01/28/2022] [Indexed: 10/19/2022]
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Fearon SH, Dennis SJ, Hitzeroth II, Rybicki EP, Meyers AE. Humoral and cell-mediated immune responses to plant-produced African horse sickness virus VP7 quasi-crystals. Virus Res 2021; 294:198284. [PMID: 33421520 DOI: 10.1016/j.virusres.2020.198284] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2020] [Revised: 12/22/2020] [Accepted: 12/26/2020] [Indexed: 11/26/2022]
Abstract
African horse sickness (AHS) is a devastating viral disease affecting equines and has resulted in many disastrous epizootics. To date, no successful therapeutic treatment exists for AHS, and commercially used live-attenuated vaccines have various undesirable side effects. Previous studies have shown that mice inoculated with insoluble African horse sickness virus (AHSV) VP7 crystals are protected from live challenge with a lethal dose of AHSV. This study investigates the humoral and cell-mediated immune responses in guinea-pigs to a safer monovalent vaccine alternative based on AHSV-5 VP7 quasi-crystals produced in plants. Guinea-pigs received prime- and boost-inoculations of between 10 and 50 μg of purified plant-produced AHSV VP7. Western immunoblot analysis of the humoral response showed stimulation of high titres of anti-VP7 antibodies 28 days after the boost-inoculation in sera from three of the five experimental animals. In addition, RNA-seq transcriptome profiling of guinea-pig spleen-derived RNA highlighted thirty significantly (q ≤ 0.05) differentially expressed genes involved in innate and adaptive immunity. Differential expression of genes involved in Th1, Th2 and Th17 cell differentiation suggest a cell-mediated immune response to AHSV-5 VP7. Upregulation of several important cytokines and cytokine receptors were noted, including TNFSF14, CX3CR1, IFNLR1 and IL17RA. Upregulation of IL17RA suggests a Th17 response which has been reported as a key component in AHSV immunity. While further investigation is needed to validate these findings, these results suggest that AHSV-5 VP7 quasi-crystals produced in N. benthamiana are immunogenic and induce both humoral and cell-mediated responses.
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Affiliation(s)
- Shelley H Fearon
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Susan J Dennis
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Inga I Hitzeroth
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Edward P Rybicki
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7700, South Africa; Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Rondebosch, Cape Town 7700, South Africa
| | - Ann E Meyers
- Biopharming Research Unit, Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town 7700, South Africa.
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Hartje LF, Snow CD. Protein crystal based materials for nanoscale applications in medicine and biotechnology. WILEY INTERDISCIPLINARY REVIEWS-NANOMEDICINE AND NANOBIOTECHNOLOGY 2018; 11:e1547. [DOI: 10.1002/wnan.1547] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2018] [Revised: 09/28/2018] [Accepted: 10/12/2018] [Indexed: 12/17/2022]
Affiliation(s)
- Luke F. Hartje
- Department of Biochemistry and Molecular Biology Colorado State University Fort Collins Colorado
| | - Christopher D. Snow
- Department of Chemical and Biological Engineering Colorado State University Fort Collins Colorado
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Mathebula EM, Faber FE, Van Wyngaardt W, Van Schalkwyk A, Pretorius A, Fehrsen J. B-cell epitopes of African horse sickness virus serotype 4 recognised by immune horse sera. ACTA ACUST UNITED AC 2017; 84:e1-e12. [PMID: 28281773 PMCID: PMC6238682 DOI: 10.4102/ojvr.v84i1.1313] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/13/2016] [Revised: 09/27/2016] [Accepted: 09/29/2016] [Indexed: 01/07/2023]
Abstract
Identifying antigenic proteins and mapping their epitopes is important for the development of diagnostic reagents and recombinant vaccines. B-cell epitopes of African horse sickness virus (AHSV) have previously been mapped on VP2, VP5, VP7 and NS1, using mouse, rabbit and chicken monoclonal antibodies. A comprehensive study of the humoral immune response of five vaccinated horses to AHSV-4 antigenic peptides was undertaken. A fragmented-genome phage display library expressing a repertoire of AHSV-4 peptides spanning the entire genome was constructed. The library was affinity selected for binders on immobilised polyclonal immunoglobulin G (IgG) isolated from horse sera collected pre- and post-immunisation with an attenuated AHSV-4 monovalent vaccine. The DNA inserts of binding phages were sequenced with Illumina high-throughput sequencing. The data were normalised using pre-immune IgG-selected sequences. More sequences mapped to the genes coding for NS3, VP6 and VP5 than to the other genes. However, VP2 and VP5 each had more antigenic regions than each of the other proteins. This study identified a number of epitopes to which the horse’s humoral immune system responds during immunisation with AHSV-4.
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Affiliation(s)
| | | | | | | | | | - Jeanni Fehrsen
- New Generation Vaccines Programme, Agricultural Research Council - Onderstepoort Veterinary Institute; Department of Veterinary Tropical Diseases, University of Pretoria.
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Kanai Y, van Rijn PA, Maris-Veldhuis M, Kaname Y, Athmaram TN, Roy P. Immunogenicity of recombinant VP2 proteins of all nine serotypes of African horse sickness virus. Vaccine 2014; 32:4932-7. [PMID: 25045805 PMCID: PMC4148702 DOI: 10.1016/j.vaccine.2014.07.031] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 06/19/2014] [Accepted: 07/08/2014] [Indexed: 12/02/2022]
Abstract
African horse sickness (AHS) is an equine disease with a mortality of up to 90% for susceptible horses. The causative agent AHS virus (AHSV) is transmitted by species of Culicoides. AHSV serogroup within the genus Orbivirus of the Reoviridae family consists of nine serotypes that show no or very limited cross-neutralization. Of the seven structural proteins (VP1-VP7) of AHSV, VP2 is the serotype specific protein, and the major target for neutralizing antibodies. In this report, recombinant VP2 proteins of all nine serotypes were expressed individually by the baculovirus expression system and the immunogenicity of each was studied by immunization of guinea pigs with single VP2 as well as with cocktails of VP2 proteins. Homologous neutralizing antibodies measured by 50% plaque reduction assay showed varying degrees (from 37 to 1365) of titers for different VP2 proteins. A low cross-neutralizing antibody titer was found for genetically related AHSV serotypes. Immunization with VP2 cocktails containing equal amounts of each of the VP2 proteins also triggered neutralizing antibodies albeit to lower titers (4-117) to each of the serotypes in the cocktail. This study is a first step to develop a VP2 subunit vaccine for AHS and our results indicate that VP2 subunit vaccines are feasible individually or in a multi-serotype cocktail.
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Affiliation(s)
- Yuta Kanai
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Piet A van Rijn
- Department of Virology, Central Veterinary Institute of Wageningen University (CVI), PO Box 65, 8200 AB Lelystad, The Netherlands; Department of Biochemistry, Centre for Human Metabonomics, North-West University, Private Bag X6001, Potchefstroom 2520, South Africa
| | - Mieke Maris-Veldhuis
- Department of Virology, Central Veterinary Institute of Wageningen University (CVI), PO Box 65, 8200 AB Lelystad, The Netherlands
| | - Yuki Kaname
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - T N Athmaram
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom
| | - Polly Roy
- Department of Pathogen Molecular Biology, London School of Hygiene and Tropical Medicine, Keppel Street, London WC1E 7HT, United Kingdom.
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Mohd Jaafar F, Belhouchet M, Vitour D, Adam M, Breard E, Zientara S, Mertens PPC, Attoui H. Immunisation with bacterial expressed VP2 and VP5 of bluetongue virus (BTV) protect α/β interferon-receptor knock-out (IFNAR(-/-)) mice from homologous lethal challenge. Vaccine 2014; 32:4059-67. [PMID: 24886956 DOI: 10.1016/j.vaccine.2014.05.056] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2014] [Revised: 04/22/2014] [Accepted: 05/15/2014] [Indexed: 12/23/2022]
Abstract
BTV-4 structural proteins VP2 (as two domains: VP2D1 and VP2D2), VP5 (lacking the first 100 amino acids: VP5Δ1-100) and full-length VP7, expressed in bacteria as soluble glutathione S-transferase (GST) fusion-proteins, were used to immunise Balb/c and α/β interferon receptor knock-out (IFNAR(-/-)) mice. Neutralising antibody (NAbs) titres (expressed as log10 of the reciprocal of the last dilution of mouse serum which reduced plaque number by ≥50%) induced by the VP2 domains ranged from 1.806 to 2.408 in Balb/c and IFNAR(-/-) mice. The immunised IFNAR(-/-) mice challenged with a homologous live BTV-4 survived and failed to develop signs of infection (ocular discharge and apathy). Although subsequent attempts to isolate virus were unsuccessful (possibly reflecting presence of neutralising antibodies), a transient/low level viraemia was detected by real time RT-PCR. In contrast, mice immunised with the two VP2 domains with or without VP5Δ1-100 and VP7, then challenged with the heterologous serotype, BTV-8, all died by day 7 post-infection. We conclude that immunisation with bacterially-expressed VP2 domains can induce strong serotype-specific NAb responses. Bacterial expression could represent a cost effective and risk-free alternative to the use of live or inactivated vaccines, particularly if viruses prove to be difficult to propagate in cell culture (like BTV-25). A vaccine based on bacterially expressed VP2 and VP5 of BTV is also DIVA-compatible.
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Affiliation(s)
- Fauziah Mohd Jaafar
- Vector-borne Viral Diseases Programme, The Pirbright Institute, Pirbright, Woking, Surrey GU240NF, United Kingdom
| | - Mourad Belhouchet
- Vector-borne Viral Diseases Programme, The Pirbright Institute, Pirbright, Woking, Surrey GU240NF, United Kingdom
| | - Damien Vitour
- Anses, INRA, ENVA-UPEC, UMR 1161 Virology Unit, French Agency for Food, Environmental and Occupational Health and Safety, Maisons-Alfort, 94703 France
| | - Micheline Adam
- Anses, INRA, ENVA-UPEC, UMR 1161 Virology Unit, French Agency for Food, Environmental and Occupational Health and Safety, Maisons-Alfort, 94703 France
| | - Emmanuel Breard
- Anses, INRA, ENVA-UPEC, UMR 1161 Virology Unit, French Agency for Food, Environmental and Occupational Health and Safety, Maisons-Alfort, 94703 France
| | - Stéphan Zientara
- Anses, INRA, ENVA-UPEC, UMR 1161 Virology Unit, French Agency for Food, Environmental and Occupational Health and Safety, Maisons-Alfort, 94703 France
| | - Peter P C Mertens
- Vector-borne Viral Diseases Programme, The Pirbright Institute, Pirbright, Woking, Surrey GU240NF, United Kingdom
| | - Houssam Attoui
- Vector-borne Viral Diseases Programme, The Pirbright Institute, Pirbright, Woking, Surrey GU240NF, United Kingdom.
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Evaluation of the immunogenicity of an experimental subunit vaccine that allows differentiation between infected and vaccinated animals against bluetongue virus serotype 8 in cattle. CLINICAL AND VACCINE IMMUNOLOGY : CVI 2013; 20:1115-22. [PMID: 23720365 DOI: 10.1128/cvi.00229-13] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Bluetongue virus (BTV), the causative agent of bluetongue in ruminants, is an emerging virus in northern Europe. The 2006 outbreak of BTV serotype 8 (BTV-8) in Europe was marked by an unusual teratogenic effect and a high frequency of clinical signs in cattle. Conventional control strategies targeting small ruminants were therefore extended to include cattle. Since cattle were not routinely vaccinated before 2006, the immune responses to BTV have not been studied extensively in this species. With the aims of developing a subunit vaccine against BTV-8 for differentiation between infected and vaccinated animals based on viral protein 7 (VP7) antibody detection and of improving the current understanding of the immunogenicity of BTV proteins in cattle, the immune responses induced by recombinant VP2 (BTV-8) and nonstructural protein 1 (NS1) and NS2 (BTV-2) were studied. Cows were immunized twice (with a 3-week interval) with the experimental vaccine, a commercial inactivated vaccine, or a placebo. The two vaccines induced similar neutralizing antibody responses to BTV-8. Furthermore, the antibody responses detected against VP2, NS1, and NS2 were strongest in the animals immunized with the experimental vaccine, and for the first time, a serotype cross-reactive antibody response to NS2 was shown in cattle vaccinated with the commercial vaccine. The two vaccines evoked measurable T cell responses against NS1, thereby supporting a bovine cross-reactive T cell response. Finally, VP7 seroconversion was observed after vaccination with the commercial vaccine, as in natural infections, but not after vaccination with the experimental vaccine, indicating that the experimental vaccine may allow the differentiation of vaccinated animals from infected animals regardless of BTV serotype. The experimental vaccine will be further evaluated during a virulent challenge in a high-containment facility.
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Franceschi V, Capocefalo A, Calvo-Pinilla E, Redaelli M, Mucignat-Caretta C, Mertens P, Ortego J, Donofrio G. Immunization of knock-out α/β interferon receptor mice against lethal bluetongue infection with a BoHV-4-based vector expressing BTV-8 VP2 antigen. Vaccine 2011; 29:3074-82. [DOI: 10.1016/j.vaccine.2011.01.075] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2010] [Revised: 01/19/2011] [Accepted: 01/23/2011] [Indexed: 11/25/2022]
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The use of soluble African horse sickness viral protein 7 as an antigen delivery and presentation system. Virus Res 2011; 156:35-48. [DOI: 10.1016/j.virusres.2010.12.015] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2010] [Revised: 12/16/2010] [Accepted: 12/23/2010] [Indexed: 11/20/2022]
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Castillo-Olivares J, Calvo-Pinilla E, Casanova I, Bachanek-Bankowska K, Chiam R, Maan S, Nieto JM, Ortego J, Mertens PPC. A modified vaccinia Ankara virus (MVA) vaccine expressing African horse sickness virus (AHSV) VP2 protects against AHSV challenge in an IFNAR -/- mouse model. PLoS One 2011; 6:e16503. [PMID: 21298069 PMCID: PMC3027694 DOI: 10.1371/journal.pone.0016503] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Accepted: 01/03/2011] [Indexed: 11/18/2022] Open
Abstract
African horse sickness (AHS) is a lethal viral disease of equids, which is transmitted by Culicoides midges that become infected after biting a viraemic host. The use of live attenuated vaccines has been vital for the control of this disease in endemic regions. However, there are safety concerns over their use in non-endemic countries. Research efforts over the last two decades have therefore focused on developing alternative vaccines based on recombinant baculovirus or live viral vectors expressing structural components of the AHS virion. However, ethical and financial considerations, relating to the use of infected horses in high biosecurity installations, have made progress very slow. We have therefore assessed the potential of an experimental mouse-model for AHSV infection for vaccine and immunology research. We initially characterised AHSV infection in this model, then tested the protective efficacy of a recombinant vaccine based on modified vaccinia Ankara expressing AHS-4 VP2 (MVA-VP2).
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Chiam R, Sharp E, Maan S, Rao S, Mertens P, Blacklaws B, Davis-Poynter N, Wood J, Castillo-Olivares J. Induction of antibody responses to African horse sickness virus (AHSV) in ponies after vaccination with recombinant modified vaccinia Ankara (MVA). PLoS One 2009; 4:e5997. [PMID: 19543394 PMCID: PMC2694985 DOI: 10.1371/journal.pone.0005997] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2008] [Accepted: 05/23/2009] [Indexed: 11/18/2022] Open
Abstract
Background African horse sickness virus (AHSV) causes a non-contagious, infectious disease in equids, with mortality rates that can exceed 90% in susceptible horse populations. AHSV vaccines play a crucial role in the control of the disease; however, there are concerns over the use of polyvalent live attenuated vaccines particularly in areas where AHSV is not endemic. Therefore, it is important to consider alternative approaches for AHSV vaccine development. We have carried out a pilot study to investigate the ability of recombinant modified vaccinia Ankara (MVA) vaccines expressing VP2, VP7 or NS3 genes of AHSV to stimulate immune responses against AHSV antigens in the horse. Methodology/Principal Findings VP2, VP7 and NS3 genes from AHSV-4/Madrid87 were cloned into the vaccinia transfer vector pSC11 and recombinant MVA viruses generated. Antigen expression or transcription of the AHSV genes from cells infected with the recombinant viruses was confirmed. Pairs of ponies were vaccinated with MVAVP2, MVAVP7 or MVANS3 and both MVA vector and AHSV antigen-specific antibody responses were analysed. Vaccination with MVAVP2 induced a strong AHSV neutralising antibody response (VN titre up to a value of 2). MVAVP7 also induced AHSV antigen–specific responses, detected by western blotting. NS3 specific antibody responses were not detected. Conclusions This pilot study demonstrates the immunogenicity of recombinant MVA vectored AHSV vaccines, in particular MVAVP2, and indicates that further work to investigate whether these vaccines would confer protection from lethal AHSV challenge in the horse is justifiable.
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Affiliation(s)
- Rachael Chiam
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Emma Sharp
- Animal Health Trust, Lanwades Park, Kentford, Newmarket, Suffolk, United Kingdom
| | - Sushila Maan
- Institute for Animal Health, Pirbright Laboratory, Pirbright, Surrey, United Kingdom
| | - Shujing Rao
- Institute for Animal Health, Pirbright Laboratory, Pirbright, Surrey, United Kingdom
| | - Peter Mertens
- Institute for Animal Health, Pirbright Laboratory, Pirbright, Surrey, United Kingdom
| | - Barbara Blacklaws
- Cambridge Infectious Diseases Consortium, Department of Veterinary Medicine, Cambridge, United Kingdom
| | - Nick Davis-Poynter
- Sir Albert Sakzewski Virus Research Centre, University of Queensland, Herston, Queensland, Australia
| | - James Wood
- Cambridge Infectious Diseases Consortium, Department of Veterinary Medicine, Cambridge, United Kingdom
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St Clair N, Shenoy B, Jacob LD, Margolin AL. Cross-linked protein crystals for vaccine delivery. Proc Natl Acad Sci U S A 1999; 96:9469-74. [PMID: 10449716 PMCID: PMC22232 DOI: 10.1073/pnas.96.17.9469] [Citation(s) in RCA: 47] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The progress toward subunit vaccines has been limited by their poor immunogenicity and limited stability. To enhance the immune response, subunit vaccines universally require improved adjuvants and delivery vehicles. In the present paper, we propose the use of cross-linked protein crystals (CLPCs) as antigens. We compare the immunogenicity of CLPCs of human serum albumin with that of soluble protein and conclude that there are marked differences in the immune response to the different forms of human serum albumin. Relative to the soluble protein, crystalline forms induce and sustain over almost a 6-month study a 6- to 10-fold increase in antibody titer for highly cross-linked crystals and an approximately 30-fold increase for lightly cross-linked crystals. We hypothesize that the depot effect, the particulate structure of CLPCs, and highly repetitive nature of protein crystals may play roles in the enhanced production of circulating antibodies. Several features of CLPCs, such as their remarkable stability, purity, biodegradability, and ease of manufacturing, make them highly attractive for vaccine formulations. This work paves the way for a systematic study of protein crystallinity and cross-linking on enhancement of humoral and T cell responses.
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Affiliation(s)
- N St Clair
- Altus Biologics Inc., 625 Putnam Avenue, Cambridge, MA 02139, USA
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O'Hara RS, Meyer AJ, Burroughs JN, Pullen L, Martin LA, Mertens PP. Development of a mouse model system, coding assignments and identification of the genome segments controlling virulence of African horse sickness virus serotypes 3 and 8. ARCHIVES OF VIROLOGY. SUPPLEMENTUM 1998; 14:259-79. [PMID: 9785512 DOI: 10.1007/978-3-7091-6823-3_23] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Attenuated (att) and wild type (wt) strains of the nine AHSV serotypes were evaluated for virulence in adult Balb C mice. Although most were avirulent in this system, isolates of AHSV 1att, 3wt, 3att, 4wt, 5att, 7att and 8att caused some mortality when administered via an intranasal route. After plaque cloning, only the attenuated vaccine strain of AHSV 7att caused any mortality via an intravenous route. AHSV 3att and AHSV 8wt were virulent (V) and avirulent (AV) (respectively) in the mouse model and were selected as parental strains for production of genome segment reassortants. These progeny virus strains were plaque cloned, then characterised to identify the genome segments that influence virulence of AHSV in the mouse model. Three virulence phenotypes were observed: fully virulent (V); fully avirulent (A); and a novel intermediate virulence (N) not expressed by either parental strain. Genome segment 2 (encoding outer capsid protein VP2) from the avirulent parent appeared to have a controlling influence in production of the A phenotype. Reassortants with the V phenotype all contained segment 2 from the virulent parent, however in each case they also contained genome segments 5 and 10, also from AHSV 3 (V). Genome segments 5 and 10 encode the smaller outer capsid protein VP5 and the non structural proteins NS3/NS3a, respectively. A combination of genome segments 2, 5 and 6 from the avirulent parent and segment 10 from the virulent parent were found in each of the virus strains with the N phenotype. However, comparison of two reassortants (A79 and A790), which differ only in a single segment, showed that replacement of genome segment 10 from the avirulent parent with that from the virulent parent, conferred the N phenotype on A790.
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Affiliation(s)
- R S O'Hara
- Institute for Animal Health, Pirbright Laboratory, Woking, U.K
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