51
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King DP, Montague N, Ebert K, Reid SM, Dukes JP, Schädlich L, Belsham GJ, Lomonossoff GP. Development of a novel recombinant encapsidated RNA particle: Evaluation as an internal control for diagnostic RT-PCR. J Virol Methods 2007; 146:218-25. [PMID: 17727966 DOI: 10.1016/j.jviromet.2007.07.002] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2007] [Revised: 06/27/2007] [Accepted: 07/04/2007] [Indexed: 11/26/2022]
Abstract
This report describes the generation of novel encapsidated RNA particles and their evaluation as in-tube internal controls in diagnostic real-time reverse-transcription PCR (rRT-PCR) assays for the detection of RNA viruses. A cassette containing sequences of 2 diagnostic primer sets for foot-and-mouth disease virus (FMDV) and a set for swine vesicular disease virus (SVDV) was engineered into a full-length cDNA clone containing the RNA-2 segment of Cowpea Mosaic Virus (CPMV). After co-inoculation with a plasmid that expressed CPMV RNA-1, recombinant virus particles were rescued from cowpea plants (Vigna unguiculata). RNA contained in these particles was amplified in diagnostic rRT-PCR assays used for detection of FMDV and SVDV. Amplification of these internal controls was used to confirm that rRT-PCR inhibitors were absent from clinical samples, thereby verifying negative assay results. The recombinant CPMVs did not reduce the analytical sensitivity of the rRT-PCRs when amplification of the insert was performed in the same tube as the diagnostic target. This system provides an attractive solution to the production of internal controls for rRT-PCR assays since CPMV grows to high yields in plants, the particles are thermostable, RNase resistant and simple purification of RNA-2 containing capsids yields a preparation which is non-infectious.
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Affiliation(s)
- Donald P King
- Institute for Animal Health, Ash Road, Pirbright, Surrey GU24 0NF, United Kingdom.
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52
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Liu J, Ma P, Sun Y, Yang M, Yang L, Li Y, Wu Y, Zhu X, Wang X. Expression of human acidic fibroblast growth factor in Nicotiana benthamiana with a potato-virus-X-based binary vector. Biotechnol Appl Biochem 2007; 48:143-7. [PMID: 17484724 DOI: 10.1042/ba20070004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The aFGF (acidic fibroblast growth factor) plays an important role in morphogenesis, angiogenesis and wound healing and is therefore of potential medical interest. A DNA fragment encoding haFGF (human aFGF) has been cloned into the PVX (potato virus X)-based binary vector (pgR107) and transiently expressed in Nicotiana benthamiana (a wild Australian tobacco) by agroinfection. Approx. 1 week after agroinfection, the recombinant haFGF accumulated in the agroinfected plants reached up to 1% of the total soluble protein. haFGF was then purified on heparin-Sepharose CL-6B. The purified haFGF could stimulate the growth of NIH 3T3 cells, suggesting that the recombinant haFGF expressed via PVX viral vector in N. benthamiana was active biologically.
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Affiliation(s)
- Jingying Liu
- Institute of Genetics and Cytology, Northeast Normal University, 5268 Renmin Street, Changchun 130024, People's Republic of China
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53
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Steinmetz NF, Evans DJ, Lomonossoff GP. Chemical Introduction of Reactive Thiols Into a Viral Nanoscaffold: A Method that Avoids Virus Aggregation. Chembiochem 2007; 8:1131-6. [PMID: 17526061 DOI: 10.1002/cbic.200700126] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The use of viral nanoparticles (VNPs) as building blocks for material fabrication has received particular attention in recent years. In earlier studies we showed the applicability of native gel electrophoresis in an agarose matrix as a useful method for the characterization of chemically modified VNPs. Here, we extend these studies and analyze the observed band pattern of intact Cowpea mosaic virus (CPMV) VNPs in agarose gels and show the applicability of native agarose gels for monitoring interparticle linkage of thiol-containing CPMV mutant particles. In addition, we report a protocol that allows the introduction of acetate-protected thiols to CPMV by means of a chemical reaction (rather than genetic modification). The advantage of this approach is that, by incorporating protected thiol groups, the formation of disulfide bonds leading to interparticle linkage is prevented. The resulting thiol-modified CPMV-SH(n) particles are stable, and following deprotection, the introduced thiols are reactive and can be labeled with thiol-selective reagents. They therefore provide a useful additional building block in the CPMV toolbox.
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Affiliation(s)
- Nicole F Steinmetz
- Department of Biological Chemistry, John Innes Centre, Colney, Norwich, Norfolk NR4 7UH, UK.
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54
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Alamillo JM, Monger W, Sola I, García B, Perrin Y, Bestagno M, Burrone OR, Sabella P, Plana‐Durán J, Enjuanes L, Lomonossoff GP, García JA. Use of virus vectors for the expression in plants of active full-length and single chain anti-coronavirus antibodies. Biotechnol J 2007; 1:1103-11. [PMID: 17004304 PMCID: PMC7161777 DOI: 10.1002/biot.200600143] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
To extend the potential of antibodies and their derivatives to provide passive protection against enteric infections when supplied orally in crude plant extracts, we have expressed both a small immune protein (SIP) and a full‐length antibody in plants using two different plant virus vectors based on potato virus X (PVX) and cowpea mosaic virus (CPMV). The agr;SIP molecule consisted of a single chain antibody (scFv) specific for the porcine coronavirus, transmissible gastroenteritis virus (TGEV) linked to the α‐CH3 domain from human IgA. To express the full‐length IgA, the individual light and heavy chains from the TGEV‐specific mAb 6A.C3 were inserted into separate PVX constructs and plants were co‐infected with both constructs. Western blot analysis revealed the efficient expression of both the SIP and IgA molecules. Analysis of crude plant extracts revealed that both the plant‐expressed αSIP and IgA molecules could bind to and neutralize TGEV in tissue culture, indicating that active molecules were produced. Oral administration of crude extracts from antibody‐expressing plant tissue to 2‐day‐old piglets showed that both the αSIP and full‐length IgA molecules can provide in vivo protection against TGEV.
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Affiliation(s)
- Josefa M. Alamillo
- Centro Nacional de Biotecnología, Campus Universidad Autónoma, Madrid, Spain
- Universidad de Córdoba, Campus Rabanales, C‐6, 14071 Córdoba, Spain
| | | | - Isabel Sola
- Centro Nacional de Biotecnología, Campus Universidad Autónoma, Madrid, Spain
| | - Beatriz García
- Centro Nacional de Biotecnología, Campus Universidad Autónoma, Madrid, Spain
| | - Yolande Perrin
- John Innes Centre, Norwich, UK
- Universitéde Technologie de Compiègne, BP 20529, 60205 Compiègne Cédex, France
| | - Marco Bestagno
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Oscar R. Burrone
- International Center for Genetic Engineering and Biotechnology, Trieste, Italy
| | - Patricia Sabella
- Fort Dodge Veterinaria SA, Carretera de Comprodon, Girona, Spain
| | - Joan Plana‐Durán
- Fort Dodge Veterinaria SA, Carretera de Comprodon, Girona, Spain
| | - Luis Enjuanes
- Centro Nacional de Biotecnología, Campus Universidad Autónoma, Madrid, Spain
| | | | - Juan A. García
- Centro Nacional de Biotecnología, Campus Universidad Autónoma, Madrid, Spain
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55
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Monger W, Alamillo JM, Sola I, Perrin Y, Bestagno M, Burrone OR, Sabella P, Plana-Duran J, Enjuanes L, Garcia JA, Lomonossoff GP. An antibody derivative expressed from viral vectors passively immunizes pigs against transmissible gastroenteritis virus infection when supplied orally in crude plant extracts. PLANT BIOTECHNOLOGY JOURNAL 2006; 4:623-31. [PMID: 17309733 PMCID: PMC7167628 DOI: 10.1111/j.1467-7652.2006.00206.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 05/14/2023]
Abstract
To investigate the potential of antibody derivatives to provide passive protection against enteric infections when supplied orally in crude plant extracts, we have expressed a small immune protein (SIP) in plants using two different plant virus vectors based on potato virus X (PVX) and cowpea mosaic virus (CPMV). The epsilonSIP molecule consisted of a single-chain antibody (scFv) specific for the porcine coronavirus transmissible gastroenteritis virus (TGEV) linked to the epsilon-CH4 domain from human immunoglobulin E (IgE). In some constructs, the sequence encoding the epsilonSIP molecule was flanked by the leader peptide from the original murine antibody at its N-terminus and an endoplasmic reticulum retention signal (HDEL) at its C-terminus to allow the expressed protein to be directed to, and retained within, the endoplasmic reticulum. Western blot analysis of samples from Nicotiana clevelandii or cowpea tissue infected with constructs revealed the presence of SIP molecules which retained their ability to dimerize. The analysis of crude plant extracts revealed that the plant-expressed epsilonSIP molecules could bind to and neutralize TGEV in tissue culture, the levels of binding and neutralization reflecting the level of expression. Oral administration of crude extracts from SIP-expressing plant tissue to 2-day-old piglets demonstrated that the extracts which showed the highest levels of in vitro neutralization could also provide in vivo protection against challenge with TGEV.
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MESH Headings
- Administration, Oral
- Animals
- Antibodies, Viral/administration & dosage
- Antibodies, Viral/immunology
- Gastroenteritis, Transmissible, of Swine/immunology
- Gastroenteritis, Transmissible, of Swine/mortality
- Genetic Vectors
- Humans
- Immunization, Passive/methods
- Immunoglobulin E/immunology
- Neutralization Tests
- Plant Extracts/immunology
- Plant Extracts/therapeutic use
- Plant Leaves/immunology
- Recombination, Genetic
- Swine
- Transmissible gastroenteritis virus/genetics
- Transmissible gastroenteritis virus/immunology
- Vaccines, Synthetic/therapeutic use
- Viral Vaccines/therapeutic use
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Affiliation(s)
- Wendy Monger
- John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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56
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Liu L, Lomonossoff G. A site-directed mutagenesis method utilising large double-stranded DNA templates for the simultaneous introduction of multiple changes and sequential multiple rounds of mutation: Application to the study of whole viral genomes. J Virol Methods 2006; 137:63-71. [PMID: 16857273 DOI: 10.1016/j.jviromet.2006.05.034] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2006] [Revised: 05/25/2006] [Accepted: 05/30/2006] [Indexed: 11/30/2022]
Abstract
A new technique for conducting site-directed mutagenesis was developed. This method allows the colour selection of mutants through the simultaneous activation or deactivation of the alpha-peptide of beta-galactosidase. Double-stranded DNA plasmids containing large inserts (at least 6.4 kbp in the present experiments) can be used as the mutational template. The method can efficiently create mutations at multiple sites simultaneously and can be used to perform multiple rounds of mutation on the same construct. The utility of the method for the analysis of viral genomes was demonstrated by applying it to the mutagenesis of a full-length cDNA copy of RNA-1 of Cowpea mosaic virus (CPMV). Six single-site mutants were initially produced which gave a variety of phenotypes when inoculated on to plants. To confirm that the phenotypes were directly caused by the introduced mutations, a second round of mutagenesis was used to create revertants of two of the mutants. In both cases, the revertants had a wild-type phenotype, demonstrating that the original phenotype was, indeed, the result of the introduced mutation. Overall, the results show that the present technique is a powerful method for site-directed mutagenesis of large DNA fragments, such as whole viral genomes, for functional studies.
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Affiliation(s)
- Li Liu
- John Innes Centre, Colney Lane, Norwich NR4 7UH, UK.
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57
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Koenig R, Lesemann DE, Loss S, Engelmann J, Commandeur U, Deml G, Schiemann J, Aust H, Burgermeister W. Zygocactus virus X-based expression vectors and formation of rod-shaped virus-like particles in plants by the expressed coat proteins of Beet necrotic yellow vein virus and Soil-borne cereal mosaic virus. J Gen Virol 2006; 87:439-443. [PMID: 16432032 DOI: 10.1099/vir.0.81477-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Expression vectors were constructed from 35S promoter-containing full-length cDNA clones of Zygocactus virus X (ZVX). The expression of foreign genes was driven by the ZVX coat protein (cp) subgenomic promoter. It was successful only when the variable region downstream of the conserved putative promoter region GSTTAAGTT(X(12-13))GAA was retained. Most of the ZVX cp gene, except for a short 3' part, was replaced by the corresponding sequence of the related Schlumbergera virus X (SVX) and its cp subgenomic promoter to enable encapsidation of the transcribed RNA by an SVX/ZVX hybrid cp. Vector-expressed cp of Beet necrotic yellow vein virus (BNYVV) assembled in Chenopodium quinoa, Tetragonia expansa and Beta vulgaris leaves into particles resembling true BNYVV particles. The virus produced from these constructs retained its ability to express BNYVV cp in local infections during successive passages on C. quinoa. This ability was lost, however, in the rarely occurring systemic infections.
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Affiliation(s)
- R Koenig
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany
| | - D-E Lesemann
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany
| | - S Loss
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany
| | - J Engelmann
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany
| | - U Commandeur
- Rheinisch-Westfälische Technische Hochschule Aachen, Institut für Biologie VII, Molekulare Biotechnologie, Worringerweg 1, D-52074 Aachen, Germany
| | - G Deml
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany
| | - J Schiemann
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany
| | - H Aust
- Technical University Braunschweig, Institut für Mikrobiologie, Spielmann-Str. 7, D-38106 Braunschweig, Germany
| | - W Burgermeister
- Biologische Bundesanstalt für Land- und Forstwirtschaft, Institut für Pflanzenvirologie, Mikrobiologie und biologische Sicherheit, Messeweg 11, D-38104 Braunschweig, Germany
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58
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Cañizares MC, Liu L, Perrin Y, Tsakiris E, Lomonossoff GP. A bipartite system for the constitutive and inducible expression of high levels of foreign proteins in plants. PLANT BIOTECHNOLOGY JOURNAL 2006; 4:183-93. [PMID: 17177795 DOI: 10.1111/j.1467-7652.2005.00170.x] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We have developed combined transgene/virus vector systems for the expression of heterologous proteins in plants. The systems are based on the bipartite RNA plant virus, cowpea mosaic virus (CPMV), and involve the amplification of integrated copies of either full-length or deleted versions of RNA-2 carrying a foreign gene. In the case of plants transgenic for full-length versions of RNA-2 carrying the green fluorescent protein (GFP), amplification can be achieved by supplying RNA-1 either exogenously or by crossing. This allows either inducible or constitutive expression of the foreign gene and results in an infection that can be passaged to further plants. Replication of deleted versions of RNA-2 harbouring GFP requires the presence of both RNA-1 and a suppressor of gene silencing, a function which we show can be supplied by HcPro from potato virus Y. Replication of the deleted versions of RNA-2 can be achieved by supplying the suppressor and RNA-1 either exogenously or by crossing, showing that this system can also be used in an inducible and constitutive format. The use of deleted forms of RNA-2 has the advantage that no infectious virus is produced, providing an effective method of biocontainment. The CPMV-based systems have advantages over existing plant expression systems in terms of the expression levels obtainable and the simplicity and flexibility of use, and should be of great practical benefit in the development of plants as bioreactors.
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59
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Chiba M, Reed JC, Prokhnevsky AI, Chapman EJ, Mawassi M, Koonin EV, Carrington JC, Dolja VV. Diverse suppressors of RNA silencing enhance agroinfection by a viral replicon. Virology 2006; 346:7-14. [PMID: 16300814 DOI: 10.1016/j.virol.2005.09.068] [Citation(s) in RCA: 120] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2005] [Revised: 08/15/2005] [Accepted: 09/21/2005] [Indexed: 11/19/2022]
Abstract
Launching the Beet yellows virus (BYV) minireplicon by agrobacterial delivery resulted in an unexpectedly low number of infected cells per inoculated leaf. This effect was due to a strong RNA silencing response in the agroinfiltrated leaves. Strikingly, ectopic co-expression of p21, a BYV RNA silencing suppressor, increased minireplicon infectivity by three orders of magnitude. Mutational analysis demonstrated that this effect correlates with suppressor activity of p21. Five diverse, heterologous viral suppressors were also active in this system, providing a useful approach for a dramatic, up to 10,000-fold, increase of the efficiency of agroinfection. The minireplicon agroinfection assay was also used to identify a new suppressor, a homolog of BYV p21, derived from Grapevine leafroll-associated virus-2. In addition, we report preliminary data on the suppressor activity of the p10 protein of Grapevine virus A and show that this protein belongs to a family of Zn-ribbon-containing proteins encoded by filamentous plant RNA viruses from three genera. The members of this family are predicted to have RNA silencing suppressor activity.
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Affiliation(s)
- Marin Chiba
- Department of Botany and Plant Pathology and Center for Gene Research and Biotechnology, Oregon State University, Corvallis, OR 97331, USA
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60
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Gopinath K, Dragnea B, Kao C. Interaction between Brome mosaic virus proteins and RNAs: effects on RNA replication, protein expression, and RNA stability. J Virol 2005; 79:14222-34. [PMID: 16254357 PMCID: PMC1280218 DOI: 10.1128/jvi.79.22.14222-14234.2005] [Citation(s) in RCA: 39] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2005] [Accepted: 08/20/2005] [Indexed: 11/20/2022] Open
Abstract
Brome mosaic virus (BMV) RNA replication has been examined in a number of systems, including Saccharomyces cerevisiae. We developed an efficient T-DNA-based gene delivery system using Agrobacterium tumefaciens to transiently express BMV RNAs in Nicotiana benthamiana. The expressed RNAs can systemically infect plants and provide material to extract BMV replicase that can perform template-dependent RNA-dependent RNA synthesis in vitro. We also expressed the four BMV-encoded proteins from nonreplicating RNAs and analyzed their effects on BMV RNA accumulation. The capsid protein that coinfiltrated with constructs expressing RNA1 and RNA2 suppressed minus-strand levels but increased plus-strand RNA accumulation. The replication proteins 1a and 2a could function in trans to replicate and transcribe the BMV RNAs. None of the BMV proteins or RNA could efficiently suppress posttranscriptional silencing. However, 1a expressed in trans will suppress the production of a recombinant green fluorescent protein expressed from the nontranslated portions of BMV RNA1 and RNA2, suggesting that 1a may regulate translation from BMV RNAs. BMV replicase proteins 1a did not affect the accumulation of the BMV RNAs in the absence of RNA replication, unlike the situation reported for S. cerevisiae. This work demonstrates that the Agrobacterium-mediated gene delivery system can be used to study the cis- and trans-acting requirements for BMV RNA replication in plants and that significant differences can exist for BMV RNA replication in different hosts.
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Affiliation(s)
- K Gopinath
- Department of Biochemistry & Biophysics, Texas A&M University, College Station, TX 77843, USA
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61
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Mechtcheriakova IA, Eldarov MA, Nicholson L, Shanks M, Skryabin KG, Lomonossoff GP. The use of viral vectors to produce hepatitis B virus core particles in plants. J Virol Methods 2005; 131:10-5. [PMID: 16112207 DOI: 10.1016/j.jviromet.2005.06.020] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2005] [Revised: 06/27/2005] [Accepted: 06/29/2005] [Indexed: 02/02/2023]
Abstract
The expression and assembly of the hepatitis B virus (HBV) nucleocapsid protein (HBcAg) were investigated in plants using viral vectors. Constructs based on either Potato virus X (PVX) or Cowpea mosaic virus (CPMV) containing the sequence of HBcAg were able to infect the appropriate host plants and remained genetically stable during infection. Analysis of HBcAg expression revealed that the protein can self-assemble into core-like particles and that the assembled material could be partially purified by differential centrifugation. Thus, the use of viral vectors can be considered a practical method for rapid production of assembled HBcAg particles in plants. This approach provides a means whereby a variety of chimaeric particles can be assessed quickly and cheaply for various diagnostic and vaccine applications.
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Affiliation(s)
- I A Mechtcheriakova
- Laboratory of Genetic Engineering, Centre Bioengineering RAS, Prospekt 60-Letya Oktyabrya, 7/1, 117312 Moscow, Russian Federation.
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62
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Liu L, Cañizares MC, Monger W, Perrin Y, Tsakiris E, Porta C, Shariat N, Nicholson L, Lomonossoff GP. Cowpea mosaic virus-based systems for the production of antigens and antibodies in plants. Vaccine 2005; 23:1788-92. [PMID: 15734042 DOI: 10.1016/j.vaccine.2004.11.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022]
Abstract
Cowpea mosaic virus (CPMV) is a bipartite RNA plant virus which has proved to be useful both for epitope presentation and as a polypeptide expression system. For epitope presentation, short antigenic sequences are expressed on the surface of the assembled virus. Chimaeric virus particles produced in this way can stimulate protective immunity in experimental animals. For polypeptide expression, we have created a vector in which foreign sequences can be inserted near the 3' end of RNA-2 and have successfully expressed a number of polypeptides in plant tissue. To extend the utility of the CPMV-based systems, we have recently developed a combined virus vector/transgenic expression system in which RNA-2 expressed from a transgene is replicated by RNA-1.
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Affiliation(s)
- Li Liu
- John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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63
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Cañizares MC, Taylor KM, Lomonossoff GP. Surface-exposed C-terminal amino acids of the small coat protein of Cowpea mosaic virus are required for suppression of silencing. J Gen Virol 2004; 85:3431-3435. [PMID: 15483261 DOI: 10.1099/vir.0.80454-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/26/2022] Open
Abstract
The small (S) coat protein of Cowpea mosaic virus (CPMV) has been identified previously as a virus-encoded suppressor of post-transcriptional gene silencing (PTGS). Deletions within the C-terminal 24 aa of this protein affect the yield and systemic spread of the virus, suggesting that the C-terminal amino acids of the S protein, which are exposed on the surface of assembled virus particles, may be responsible for the suppressor activity. To investigate this, versions of CPMV RNA-2 with deletions at the C terminus of the S protein were tested for their ability to counteract PTGS in leaf-patch tests. The results showed that the C-terminal 16 aa of the S protein are particularly important for suppressing PTGS and that these amino acids are virus-specific and cannot be substituted by the equivalent sequence from the related virus Bean pod mottle virus.
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Affiliation(s)
- M Carmen Cañizares
- Department of Metabolic Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | - Kathryn M Taylor
- Department of Metabolic Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
| | - George P Lomonossoff
- Department of Metabolic Biology, John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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64
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Liang D, Gray SM, Kaplan I, Palukaitis P. Site-directed mutagenesis and generation of chimeric viruses by homologous recombination in yeast to facilitate analysis of plant-virus interactions. MOLECULAR PLANT-MICROBE INTERACTIONS : MPMI 2004; 17:571-576. [PMID: 15195939 DOI: 10.1094/mpmi.2004.17.6.571] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/24/2023]
Abstract
A yeast homologous recombination system was used to generate mutants and chimeras in the genome of Potato leafroll virus (PLRV). A yeast-bacteria shuttle vector was developed that allows mutants and chimeras generated in yeast to be transformed into Escherichia coli for confirmation of the mutations and transformed into Agrobacterium tumefaciens to facilitate agroinfection of plants by the mutant PLRV genomes. The advantages of the system include the high frequency of recovered mutants generated by yeast homologous recombination, the ability to generate over 20 mutants and chimeras using only two restriction endonuclease sites, the ability to introduce multiple additional sequences using three and four DNA fragments, and the mobilization of the same plasmid from yeast to E. coli, A. tumefaciens, and plants. The wild-type PLRV genome showed no loss of virulence after sequential propagation in yeast, E. coli, and A. tumefaciens. Moreover, many PLRV clones with mutations generated in the capsid protein and readthrough domain of the capsid protein replicated and moved throughout plants. This approach will facilitate the analysis of plant-virus interactions of in vivo-generated mutants for many plant viruses, especially those not transmissible mechanically to plants.
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Affiliation(s)
- Delin Liang
- United States Department of Agriculture-Agricultural Research Service and Department of Plant Pathology, Cornell University, Ithaca, NY 14850, USA
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65
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Liu L, Grainger J, Cañizares MC, Angell SM, Lomonossoff GP. Cowpea mosaic virus RNA-1 acts as an amplicon whose effects can be counteracted by a RNA-2-encoded suppressor of silencing. Virology 2004; 323:37-48. [PMID: 15165817 DOI: 10.1016/j.virol.2004.02.013] [Citation(s) in RCA: 51] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2003] [Revised: 01/15/2004] [Accepted: 02/10/2004] [Indexed: 11/19/2022]
Abstract
Lines of Nicotiana benthamiana transgenic for full-length copies of both Cowpea mosaic virus (CPMV) genomic RNAs, either singly or together, have been produced. Plants transgenic for both RNAs developed symptoms characteristic of a CPMV infection. When plants transgenic for RNA-1 were agro-inoculated with RNA-2, no infection developed and the plants were also resistant to challenge with CPMV. By contrast, plants transgenic for RNA-2 became infected when agro-inoculated with RNA-1 and were fully susceptible to CPMV infection. The resistance of RNA-1 transgenic plants was shown to be related to the ability of RNA-1 to self-replicate and act as an amplicon. The ability of transgenically expressed RNA-2 to counteract the amplicon effect suggested that it encodes a suppressor of posttranscriptional gene silencing (PTGS). By examining the ability of portions of RNA-2 to reverse PTGS in N. benthamiana, we have identified the small (S) coat protein as the CPMV RNA-2-encoded suppressor of PTGS.
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Affiliation(s)
- Li Liu
- John Innes Centre, Colney Lane, Norwich NR4 7UH, UK
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Gleba Y, Marillonnet S, Klimyuk V. Engineering viral expression vectors for plants: the 'full virus' and the 'deconstructed virus' strategies. CURRENT OPINION IN PLANT BIOLOGY 2004; 7:182-8. [PMID: 15003219 DOI: 10.1016/j.pbi.2004.01.003] [Citation(s) in RCA: 113] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/07/2023]
Abstract
Plant viral vectors are being successfully developed and exploited for the industrial-scale expression of heterologous proteins and as a research tool for studies of gene expression. The initial engineering strategy (the 'full virus' vector strategy) aimed to design a vector that was essentially a wildtype virus, which was modified to carry and express a heterologous sequence that encoded a gene of interest. The new emerging trend (the 'deconstructed virus' vector strategy) reflects an ideology that recognises the inherent limitations of the viral process. It attempts to 'deconstruct' the virus, by eliminating functions that are limiting or undesired, and to rebuild it, either by delegating the missing necessary functions to the host (which is genetically modified to provide those functions) or by replacing them with analogous functions that are not derived from a virus.
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Affiliation(s)
- Yuri Gleba
- Biozentrum Halle, Weinbergweg 22, D-06120 Halle (Saale), Germany.
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