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Chen YL, Bao CJ, Duan JL, Xie Y, Lu WL. Overcoming biological barriers by virus-like drug particles for drug delivery. Adv Drug Deliv Rev 2023; 203:115134. [PMID: 37926218 DOI: 10.1016/j.addr.2023.115134] [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: 09/09/2023] [Revised: 10/27/2023] [Accepted: 10/30/2023] [Indexed: 11/07/2023]
Abstract
Virus-like particles (VLPs) have natural structural antigens similar to those found in viruses, making them valuable in vaccine immunization. Furthermore, VLPs have demonstrated significant potential in drug delivery, and emerged as promising vectors for transporting chemical drug, genetic drug, peptide/protein, and even nanoparticle drug. With virus-like permeability and strong retention, they can effectively target specific organs, tissues or cells, facilitating efficient intracellular drug release. Further modifications allow VLPs to transfer across various physiological barriers, thus acting the purpose of efficient drug delivery and accurate therapy. This article provides an overview of VLPs, covering their structural classifications, deliverable drugs, potential physiological barriers in drug delivery, strategies for overcoming these barriers, and future prospects.
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Affiliation(s)
- Yu-Ling Chen
- State Key Laboratory of Natural and Biomimetic Drugs, Beijing Key Laboratory of Molecular Pharmaceutics and Drug Delivery Systems, and School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Chun-Jie Bao
- State Key Laboratory of Natural and Biomimetic Drugs, Beijing Key Laboratory of Molecular Pharmaceutics and Drug Delivery Systems, and School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; School of Medicine & Holistic Integrative Medicine, Nanjing University of Chinese Medicine, Nanjing 210023, China; Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Jia-Lun Duan
- State Key Laboratory of Natural and Biomimetic Drugs, Beijing Key Laboratory of Molecular Pharmaceutics and Drug Delivery Systems, and School of Pharmaceutical Sciences, Peking University, Beijing 100191, China; Jiangsu Collaborative Innovation Center of Chinese Medicinal Resources Industrialization, Nanjing University of Chinese Medicine, Nanjing 210023, China
| | - Ying Xie
- State Key Laboratory of Natural and Biomimetic Drugs, Beijing Key Laboratory of Molecular Pharmaceutics and Drug Delivery Systems, and School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
| | - Wan-Liang Lu
- State Key Laboratory of Natural and Biomimetic Drugs, Beijing Key Laboratory of Molecular Pharmaceutics and Drug Delivery Systems, and School of Pharmaceutical Sciences, Peking University, Beijing 100191, China.
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Hu D, Xie X, Zhang T, Yu Y, Xu Z, Zhang Y, Liu Q. A lef5-deficient baculovirus expression system with no virion contamination and promoting secretion. J Biotechnol 2023; 365:20-28. [PMID: 36709001 DOI: 10.1016/j.jbiotec.2023.01.013] [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: 11/25/2022] [Accepted: 01/24/2023] [Indexed: 01/26/2023]
Abstract
The baculovirus expression system (BEVS) is widely used in biomanufacturing. However, massive late and very late genes are expressed during baculovirus infection of the host cell, and the protein aggregation has a significant negative impact on the intercellular environment of cells and organelle function. Baculovirus particle contamination also hinders the purification of particulate products. In this study, a novel baculovirus vector of deficient-lef5 (Ac-Δlef5) was established to prevent the production of baculovirus particles. It could transduce cells and replicate viral DNA but the expression of the late and very late genes was reduced so that no virus was packed and budded. The Ac-Δlef5 expression system was successfully used to express a secreted protein, thyroid peroxidase (TPO). Compared to wild-type baculovirus (Ac-wt), Ac-Δlef5 delayed the decline in cell viability and prolonged the harvest period from 4 to 6 days after infection. When expressed in the Ac-Δlef5 system, 98% of TPO was secreted extracellularly, which was about 1.8 times that of the Ac-wt system. Meanwhile, the transcription levels of protein folding-related genes were significantly increased. The results show that the Ac-Δlef5 system is a potential novel viral-free baculovirus expression system, which omits the virion removal operation in biomanufacturing.
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Affiliation(s)
- Die Hu
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai 200237, China
| | - Xueman Xie
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai 200237, China
| | - Tong Zhang
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai 200237, China
| | - Yue Yu
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai 200237, China
| | - Zhenhe Xu
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai 200237, China
| | - Yuanxing Zhang
- Shanghai Collaborative Innovation Center for Biomanufacturing, 130 Meilong Road, Shanghai 200237, China
| | - Qin Liu
- State Key Laboratory of Bioreactor Engineering, Shanghai Frontiers Science Center of Optogenetic Techniques for Cell Metabolism, East China University of Science and Technology, Shanghai 200237, China; Shanghai Collaborative Innovation Center for Biomanufacturing, 130 Meilong Road, Shanghai 200237, China.
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Gupta R, Arora K, Roy SS, Joseph A, Rastogi R, Arora NM, Kundu PK. Platforms, advances, and technical challenges in virus-like particles-based vaccines. Front Immunol 2023; 14:1123805. [PMID: 36845125 PMCID: PMC9947793 DOI: 10.3389/fimmu.2023.1123805] [Citation(s) in RCA: 16] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2022] [Accepted: 01/30/2023] [Indexed: 02/11/2023] Open
Abstract
Viral infectious diseases threaten human health and global stability. Several vaccine platforms, such as DNA, mRNA, recombinant viral vectors, and virus-like particle-based vaccines have been developed to counter these viral infectious diseases. Virus-like particles (VLP) are considered real, present, licensed and successful vaccines against prevalent and emergent diseases due to their non-infectious nature, structural similarity with viruses, and high immunogenicity. However, only a few VLP-based vaccines have been commercialized, and the others are either in the clinical or preclinical phases. Notably, despite success in the preclinical phase, many vaccines are still struggling with small-scale fundamental research owing to technical difficulties. Successful production of VLP-based vaccines on a commercial scale requires a suitable platform and culture mode for large-scale production, optimization of transduction-related parameters, upstream and downstream processing, and monitoring of product quality at each step. In this review article, we focus on the advantages and disadvantages of various VLP-producing platforms, recent advances and technical challenges in VLP production, and the current status of VLP-based vaccine candidates at commercial, preclinical, and clinical levels.
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Affiliation(s)
| | | | | | | | | | | | - Prabuddha K. Kundu
- Department of Research and Development, Premas Biotech Pvt Ltd., Sector IV, Industrial Model Township (IMT), Manesar, Gurgaon, India
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Abstract
Animal cell culture technology in today’s scenario has become indispensable in the field of life sciences, which provides a basis to study regulation, proliferation, and differentiation and to perform genetic manipulation. It requires specific technical skills to carry out successfully. This chapter describes the essential techniques of animal cell culture as well as its applications.
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Affiliation(s)
- Anju Verma
- Department of Plant Pathology, Institute of Plant Breeding Genetics & Genomics, Center for Applied Genetic Technologies, University of Georgia, Athens, GA, United States
| | - Megha Verma
- College of Arts and Sciences, St. Louis, MO, United States
| | - Anchal Singh
- Department of Biochemistry, Institute of Science, Banaras Hindu University, Varanasi, UP, India
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Fuenmayor J, Gòdia F, Cervera L. Production of virus-like particles for vaccines. N Biotechnol 2017; 39:174-180. [PMID: 28778817 PMCID: PMC7102714 DOI: 10.1016/j.nbt.2017.07.010] [Citation(s) in RCA: 171] [Impact Index Per Article: 24.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/07/2016] [Revised: 07/24/2017] [Accepted: 07/30/2017] [Indexed: 01/23/2023]
Abstract
Virus-like particles (VLPs) are nanostructures that resemble the structures of viruses. They are composed of one or more structural proteins that can be arranged in several layers and can also contain a lipid outer envelope. VLPs trigger a high humoral and cellular immune response due to their repetitive structures. A key factor regarding VLP safety is the lack of viral genomic material, which enhances safety during both manufacture and administration. Contemporary VLP production may take advantage of several systems, including bacterial, yeast, insect and mammalian cells. The choice of production platform depends on several factors, including cost and the need for post-translational modifications (PTMs), which can be essential in generating an optimal immune response. Some VLP-based vaccines designed to prevent several infectious diseases are already approved and on the market, with many others at the clinical trial or research stage. Interest in this technology has recently increased due to its advantages over classical vaccines. This paper reviews the state-of-the-art of VLP production systems and the newest generation of VLP-based vaccines now available.
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Affiliation(s)
- J Fuenmayor
- Grup d'Enginyeria Cel·lular i Bioprocés, Escola d'Enginyeria, Universitat Autònoma de Barcelona, Campus de Bellaterra, Cerdanyola del Vallès, Barcelona, Spain.
| | - F Gòdia
- Grup d'Enginyeria Cel·lular i Bioprocés, Escola d'Enginyeria, Universitat Autònoma de Barcelona, Campus de Bellaterra, Cerdanyola del Vallès, Barcelona, Spain
| | - L Cervera
- Viral Vectors and Vaccines Bioprocessing Group, Department of Bioengineering, 817 Sherbrooke Street West, Room 270, Macdonald Engineering Building, McGill University, H3A 0C3, Montreal, QC, Canada
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Petiot E, Ansorge S, Rosa-Calatrava M, Kamen A. Critical phases of viral production processes monitored by capacitance. J Biotechnol 2016; 242:19-29. [PMID: 27867077 DOI: 10.1016/j.jbiotec.2016.11.010] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2016] [Revised: 11/07/2016] [Accepted: 11/10/2016] [Indexed: 11/28/2022]
Abstract
Over the last decade industrial manufacturing of viral vaccines and viral vectors for prophylactic and therapeutic applications is experiencing a remarkable growth. Currently, the quality attributes of viral derived products are assessed only at the end-point of the production process, essentially because in-process monitoring tools are not available or not implemented at industrial scale. However, to demonstrate process reproducibility and robustness, manufacturers are strongly advised by regulatory agencies to adopt more on-line process monitoring and control. Dielectric spectroscopy has been successfully used as an excellent indicator of the cell culture state in mammalian and yeast cell systems. We previously reported the use of this technique for monitoring influenza and lentiviral productions in HEK293 cell cultures. For both viruses, multi-frequency capacitance measurements allowed not only the on-line monitoring of the production kinetics, but also the identification of the viral release time from the cells. The present study demonstrates that the same approach can be successfully exploited for the on-line monitoring of different enveloped and non-enveloped virus production kinetics in cell culture processes. The on-line monitoring multi-frequency capacitance method was assessed in human HEK293 and Sf9 insect cells expression systems, with viral productions initiated by either infection or transfection. The comparative analyses of all the data acquired indicate that the characteristic capacitance signals were highly correlated with the occurrence of viral replication phases. Furthermore the evolution of the cell dielectric properties (intracellular conductivity and membrane capacitance) were indicative of each main replication steps. In conclusion, multi-frequency capacitance has a great potential for on-line monitoring, supervision and control of viral vector production in cell culture processes.
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Affiliation(s)
- Emma Petiot
- NRC, Human Health Therapeutics Portfolio, 6100 Royalmount Ave, Montréal, QC, H4P 2R2, Canada; Virologie et Pathologie Humaine - VirPath Team, International Center for Infectious diseases Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Faculté de Médecine RTH Laennec, Lyon, France.
| | - Sven Ansorge
- NRC, Human Health Therapeutics Portfolio, 6100 Royalmount Ave, Montréal, QC, H4P 2R2, Canada.
| | - Manuel Rosa-Calatrava
- Virologie et Pathologie Humaine - VirPath Team, International Center for Infectious diseases Research, Inserm U1111, CNRS UMR5308, ENS Lyon, Université Claude Bernard Lyon 1, Faculté de Médecine RTH Laennec, Lyon, France.
| | - Amine Kamen
- NRC, Human Health Therapeutics Portfolio, 6100 Royalmount Ave, Montréal, QC, H4P 2R2, Canada; McGill University, Bioengineering Dpt. 817, Sherbrooke St. W., Montreal, QC, H2 B 2C6, Canada.
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Identification of Essential Genetic Baculoviral Elements for Recombinant Protein Expression by Transactivation in Sf21 Insect Cells. PLoS One 2016; 11:e0149424. [PMID: 26934632 PMCID: PMC4774975 DOI: 10.1371/journal.pone.0149424] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Accepted: 01/31/2016] [Indexed: 12/29/2022] Open
Abstract
The Baculovirus Expression Vector System (BEVS) is widely used to produce high amounts of recombinant proteins. Nevertheless, generating recombinant baculovirus in high quality is rather time-consuming and labor-intensive. Alternatively, virus-free expression in insect cells did not achieve similar expression levels for most proteins so far. The transactivation method is a promising approach for protein expression in Sf21 cells. It combines advantages of BEVS and plasmid-based expression by activating strong virus-dependent promoters on a transfected plasmid by baculoviral coinfection. Here, we identified expression elements required for transactivation. Therefore, we designed several vectors comprising different viral promoters or promoter combinations and tested them for eGFP expression using the automated BioLector microcultivation system. Remarkably, only the combination of the very late promoter p10 together with the homologous region 5 (hr5) could boost expression during transactivation. Other elements, like p10 alone or the late viral promoter polH, did not respond to transactivation. A new combination of hr5 and p10 with the strongest immediate early OpMNPV viral promoter OpIE2 improved the yield of eGFP by ~25% in comparison to the previous applied hr5-IE1-p10 expression cassette. Furthermore, we observed a strong influence of the transcription termination sequence and vector backbone on the level of expression. Finally, the expression levels for transactivation, BEVS and solely plasmid-based expression were compared for the marker protein eGFP, underlining the potential of transactivation for fast recombinant protein expression in Sf21 cells. In conclusion, essential elements for transactivation could be identified. The optimal elements were applied to generate an improved vector applicable in virus-free plasmid-based expression, transactivation and BEVS.
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Abstract
For the purpose of this work, insect biotechnology, which is also known as yellow biotechnology, is the use of insects as well as insect-derived cells or molecules in medical (red biotechnology), agricultural (green biotechnology), and industrial (white) biotechnology. It is based on the application of biotechnological techniques on insects or their cells to develop products or services for human use. Such products are then applied in agriculture, medicine, and industrial biotechnology. Insect biotechnology has proven to be a useful resource in diverse industries, especially for the production of industrial enzymes including chitinases and cellulases, pharmaceuticals, microbial insecticides, insect genes, and many other substances. Insect cells (ICs), and particularly lepidopteran cells, constitute a competitive strategy to mammalian cells for the manufacturing of biotechnology products. Among the wide range of methods and expression hosts available for the production of biotech products, ICs are ideal for the production of complex proteins requiring extensive posttranslational modification. The progress so far made in insect biotechnology essentially derives from scientific breakthroughs in molecular biology, especially with the advances in techniques that allow genetic manipulation of organisms and cells. Insect biotechnology has grown tremendously in the last 30 years.
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Affiliation(s)
- Chandrasekar Raman
- Department of Biochemistry and Molecular Biophysics, Kansas State University, Manhattan, Kansas USA
| | - Marian R. Goldsmith
- Biological Sciences Department Center for Biotech. and Life Sciences, University of Rhode Island, Kingston, Rhode Island USA
| | - Tolulope A. Agunbiade
- Department of Internal Medicine, Yale University School of Medicine, New Haven, Connecticut USA
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Jacinto M, Soares R, Azevedo A, Chu V, Tover A, Conde J, Aires-Barros M. Optimization and miniaturization of aqueous two phase systems for the purification of recombinant human immunodeficiency virus-like particles from a CHO cell supernatant. Sep Purif Technol 2015. [DOI: 10.1016/j.seppur.2015.09.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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Nieto K, Weghofer M, Sehr P, Ritter M, Sedlmeier S, Karanam B, Seitz H, Müller M, Kellner M, Hörer M, Michaelis U, Roden RBS, Gissmann L, Kleinschmidt JA. Development of AAVLP(HPV16/31L2) particles as broadly protective HPV vaccine candidate. PLoS One 2012; 7:e39741. [PMID: 22761884 PMCID: PMC3384601 DOI: 10.1371/journal.pone.0039741] [Citation(s) in RCA: 63] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2012] [Accepted: 05/25/2012] [Indexed: 12/21/2022] Open
Abstract
The human papillomavirus (HPV) minor capsid protein L2 is a promising candidate for a broadly protective HPV vaccine yet the titers obtained in most experimental systems are rather low. Here we examine the potential of empty AAV2 particles (AAVLPs), assembled from VP3 alone, for display of L2 epitopes to enhance their immunogenicity. Insertion of a neutralizing epitope (amino acids 17–36) from L2 of HPV16 and HPV31 into VP3 at positions 587 and 453, respectively, permitted assembly into empty AAV particles (AAVLP(HPV16/31L2)). Intramuscularly vaccination of mice and rabbits with AAVLP(HPV16/31L2)s in montanide adjuvant, induced high titers of HPV16 L2 antibodies as measured by ELISA. Sera obtained from animals vaccinated with the AAVLP(HPV16/31L2)s neutralized infections with several HPV types in a pseudovirion infection assay. Lyophilized AAVLP(HPV16/31L2) particles retained their immunogenicity upon reconstitution. Interestingly, vaccination of animals that were pre-immunized with AAV2 - simulating the high prevalence of AAV2 antibodies in the population - even increased cross neutralization against HPV31, 45 and 58 types. Finally, passive transfer of rabbit antisera directed against AAVLP(HPV16/31L2)s protected naïve mice from vaginal challenge with HPV16 pseudovirions. In conclusion, AAVLP(HPV16/31L2) particles have the potential as a broadly protective vaccine candidate regardless of prior exposure to AAV.
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Affiliation(s)
- Karen Nieto
- Research Program Infection and Cancer, German Cancer Research Center, Heidelberg, Germany.
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Roldão A, Mellado MCM, Castilho LR, Carrondo MJT, Alves PM. Virus-like particles in vaccine development. Expert Rev Vaccines 2011; 9:1149-76. [PMID: 20923267 DOI: 10.1586/erv.10.115] [Citation(s) in RCA: 574] [Impact Index Per Article: 44.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
Virus-like particles (VLPs) are multiprotein structures that mimic the organization and conformation of authentic native viruses but lack the viral genome, potentially yielding safer and cheaper vaccine candidates. A handful of prophylactic VLP-based vaccines is currently commercialized worldwide: GlaxoSmithKline's Engerix (hepatitis B virus) and Cervarix (human papillomavirus), and Merck and Co., Inc.'s Recombivax HB (hepatitis B virus) and Gardasil (human papillomavirus) are some examples. Other VLP-based vaccine candidates are in clinical trials or undergoing preclinical evaluation, such as, influenza virus, parvovirus, Norwalk and various chimeric VLPs. Many others are still restricted to small-scale fundamental research, despite their success in preclinical tests. This article focuses on the essential role of VLP technology in new-generation vaccines against prevalent and emergent diseases. The implications of large-scale VLP production are discussed in the context of process control, monitorization and optimization. The main up- and down-stream technical challenges are identified and discussed accordingly. Successful VLP-based vaccine blockbusters are briefly presented concomitantly with the latest results from clinical trials and the recent developments in chimeric VLP-based technology for either therapeutic or prophylactic vaccination.
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Affiliation(s)
- António Roldão
- Instituto de Tecnologia Química e Biológica/Universidade Nova de Lisboa, Apartado 127, P-2781-901, Oeiras, Portugal
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Park SW, Choi JH, Goo TW, Kim SR, Lee GG, Kang SW. Mouse Dual Ig Domain Containing Cell Adhesion Molecule Protein Expression and Purification Using the Baculovirus Expression Vector System. ACTA ACUST UNITED AC 2010. [DOI: 10.4167/jbv.2010.40.3.123] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Affiliation(s)
- Seung-Won Park
- Department of Agricultural Biology, National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea
| | - Ji-Hyun Choi
- Department of Agricultural Biology, National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea
| | - Tae-Won Goo
- Department of Agricultural Biology, National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea
| | - Seong Ryul Kim
- Department of Agricultural Biology, National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea
| | - Gwang-Gill Lee
- Department of Agricultural Biology, National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea
| | - Seok-Woo Kang
- Department of Agricultural Biology, National Academy of Agricultural Science, Rural Development Administration, Suwon, Korea
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Sivakumar S, Wang Z, Harrison RL, Liu S, Miller WA, Bonning BC. Baculovirus-expressed virus-like particles of Pea enation mosaic virus vary in size and encapsidate baculovirus mRNAs. Virus Res 2009; 139:54-63. [PMID: 19013202 DOI: 10.1016/j.virusres.2008.10.002] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2008] [Revised: 09/30/2008] [Accepted: 10/10/2008] [Indexed: 11/24/2022]
Abstract
Pea enation mosaic virus (PEMV: family Luteoviridae) is transmitted in a persistent, circulative manner by aphids. We inserted cDNAs encoding the structural proteins of PEMV, the coat protein (CP) and coat protein-read through domain (CPRT) into the genome of the baculovirus Autographa californica multiple nucleopolyhedrovirus with and without a histidine tag or an upstream Kozak consensus sequence. The Sf21 cell line provided the highest level of CP expression of the cell lines tested and resulted in production of virus-like particles (VLPs). The CPRT was not detected in recombinant baculovirus-infected cells by Western blot. Addition of a Kozak sequence increased the yield of baculovirus produced VLPs. Baculovirus-expressed VLPs purified on a nickel NTA column were of variable size (13-30 nm) and contained CP mRNA. The purified VLPs were also shown by RT-PCR to contain 70% of 154 baculovirus mRNAs, indicative of non-specific RNA encapsidation in the absence of viral RNA replication. When fed to the pea aphid, Acyrthosiphon pisum (Harris), the VLPs entered the aphid hemocoel, demonstrating that CPRT is not required for uptake of PEMV from the aphid gut. Baculovirus expression of PEMV VLPs provides a useful tool for future analysis of RNA encapsidation requirements and molecular aphid-virus interactions.
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Affiliation(s)
- S Sivakumar
- Department of Entomology, Iowa State University, Ames, IA 50011-3222, United States
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Intron splicing-mediated expression of AAV Rep and Cap genes and production of AAV vectors in insect cells. Mol Ther 2008; 16:924-30. [PMID: 18388928 DOI: 10.1038/mt.2008.35] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
An artificial intron containing the insect cell polyhedrin (polh) promoter was designed, constructed, and inserted into the adeno-associated virus (AAV) Rep and Cap coding sequences to express the Rep and Cap proteins, respectively. The artificial intron was spliced out and full-length Rep78 or VP1 proteins were expressed from the insect promoters located upstream of their respective AUG start codons. The polh promoter located inside the artificial intron was functional, expressed the Rep52 or VP2/VP3 proteins located downstream of the artificial intron, and overlapped with the Rep78 or VP1 proteins. This is the first report that an artificial intron containing an insect cell promoter can be inserted into a coding sequence to express genes with overlapping open-reading frames (ORFs). A method was also established for AAV vector production in insect cells with these intron-containing Rep and Cap coding sequences, and the vectors produced thereby were infectious. These intron-containing AAV Rep and Cap coding sequences were very stable in recombinant baculoviruses and showed no apparent loss of protein expression even after five consecutive amplifications of the plaque-purified recombinant baculoviruses. This newly established AAV production method should prove to be a useful tool for large-scale AAV vector production.
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