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Chen Y, Hu S, Lee W, Walsh N, Iozza K, Huang N, Preston G, Drouin LM, Jia N, Deng J, Hebben M, Liao J. A Comprehensive Study of the Effects by Sequence Truncation within Inverted Terminal Repeats (ITRs) on the Productivity, Genome Packaging, and Potency of AAV Vectors. Microorganisms 2024; 12:310. [PMID: 38399714 PMCID: PMC10892565 DOI: 10.3390/microorganisms12020310] [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: 12/17/2023] [Revised: 01/23/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
One of the primary challenges in working with adeno-associated virus (AAV) lies in the inherent instability of its inverted terminal repeats (ITRs), which play vital roles in AAV replication, encapsidation, and genome integration. ITRs contain a high GC content and palindromic structure, which occasionally results in truncations and mutations during plasmid amplification in bacterial cells. However, there is no thorough study on how these alterations in ITRs impact the ultimate AAV vector characteristics. To close this gap, we designed ITRs with common variations, including a single B, C, or D region deletion at one end, and dual deletions at both ends of the vector genome. These engineered ITR-carrying plasmids were utilized to generate AAV vectors in HEK293 cells. The crude and purified AAV samples were collected and analyzed for yield, capsid DNA-filled percentage, potency, and ITR integrity. The results show that a single deletion had minor impact on AAV productivity, packaging efficiency, and in vivo potency. However, deletions on both ends, except A, showed significant negative effects on the above characteristics. Our work revealed the role of ITR regions, A, B, C, and D for AAV production and DNA replication, and proposes a new strategy for the quality control of ITR-bearing plasmids and final AAV products.
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Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Jing Liao
- Genomic Medicine, Alexion, AstraZeneca Rare Disease, 65 Hayden Avenue, Lexington, MA 02421, USA; (Y.C.); (S.H.); (W.L.); (N.W.); (K.I.); (N.H.); (G.P.); (L.M.D.); (N.J.); (J.D.); (M.H.)
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2
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Puzzo F, Zhang C, Powell Gray B, Zhang F, Sullenger BA, Kay MA. Aptamer-programmable adeno-associated viral vectors as a novel platform for cell-specific gene transfer. MOLECULAR THERAPY. NUCLEIC ACIDS 2023; 31:383-397. [PMID: 36817723 PMCID: PMC9929486 DOI: 10.1016/j.omtn.2023.01.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/12/2022] [Accepted: 01/19/2023] [Indexed: 01/22/2023]
Abstract
Adeno-associated viruses (AAVs) are commonly used for in vivo gene therapy. Nevertheless, the wide tropism that characterizes these vectors limits specific targeting to a particular cell type or tissue. Here, we developed new chemically modified AAV vectors (Nε-AAVs) displaying a single site substitution on the capsid surface for post-production vector engineering through biorthogonal copper-free click chemistry. We were able to identify AAV vectors that would tolerate the unnatural amino acid substitution on the capsid without disrupting their packaging efficiency. We functionalized the Nε-AAVs through conjugation with DNA (AS1411) or RNA (E3) aptamers or with a folic acid moiety (FA). E3-, AS1411-, and FA-AAVs showed on average a 3- to 9-fold increase in transduction compared with their non-conjugated counterparts in different cancer cell lines. Using specific competitors, we established ligand-specific transduction. In vivo studies confirmed the selective uptake of FA-AAV and AS1411-AAV without off-target transduction in peripheral organs. Overall, the high versatility of these novel Nε-AAVs might pave the way to tailoring gene therapy vectors toward specific types of cells both for ex vivo and in vivo applications.
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Affiliation(s)
- Francesco Puzzo
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Chuanling Zhang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
- State Key Laboratory of Natural and Biomimetic Drugs, School of Pharmaceutical Sciences, Peking University, Beijing 100191, China
| | - Bethany Powell Gray
- Department of Surgery, Duke University School of Medicine, Durham, NC 27705, USA
| | - Feijie Zhang
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
| | - Bruce A. Sullenger
- Department of Surgery, Duke University School of Medicine, Durham, NC 27705, USA
| | - Mark A. Kay
- Departments of Pediatrics and Genetics, Stanford University, Stanford, CA 94305, USA
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3
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Shitik EM, Shalik IK, Yudkin DV. AAV- based vector improvements unrelated to capsid protein modification. Front Med (Lausanne) 2023; 10:1106085. [PMID: 36817775 PMCID: PMC9935841 DOI: 10.3389/fmed.2023.1106085] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/16/2023] [Indexed: 02/05/2023] Open
Abstract
Recombinant adeno-associated virus (rAAV) is the leading platform for delivering genetic constructs in vivo. To date, three AAV-based gene therapeutic agents have been approved by the FDA and are used in clinical practice. Despite the distinct advantages of gene therapy development, it is clear that AAV vectors need to be improved. Enhancements in viral vectors are mainly associated with capsid protein modifications. However, there are other structures that significantly affect the AAV life cycle and transduction. The Rep proteins, in combination with inverted terminal repeats (ITRs), determine viral genome replication, encapsidation, etc. Moreover, transgene cassette expression in recombinant variants is directly related to AAV production and transduction efficiency. This review discusses the ways to improve AAV vectors by modifying ITRs, a transgene cassette, and the Rep proteins.
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Direct Capsid Labeling of Infectious HIV-1 by Genetic Code Expansion Allows Detection of Largely Complete Nuclear Capsids and Suggests Nuclear Entry of HIV-1 Complexes via Common Routes. mBio 2022; 13:e0195922. [PMID: 35972146 PMCID: PMC9600849 DOI: 10.1128/mbio.01959-22] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
The cone-shaped mature HIV-1 capsid is the main orchestrator of early viral replication. After cytosolic entry, it transports the viral replication complex along microtubules toward the nucleus. While it was initially believed that the reverse transcribed genome is released from the capsid in the cytosol, recent observations indicate that a high amount of capsid protein (CA) remains associated with subviral complexes during import through the nuclear pore complex (NPC). Observation of postentry events via microscopic detection of HIV-1 CA is challenging, since epitope shielding limits immunodetection and the genetic fragility of CA hampers direct labeling approaches. Here, we present a minimally invasive strategy based on genetic code expansion and click chemistry that allows for site-directed fluorescent labeling of HIV-1 CA, while retaining virus morphology and infectivity. Thereby, we could directly visualize virions and subviral complexes using advanced microscopy, including nanoscopy and correlative imaging. Quantification of signal intensities of subviral complexes revealed an amount of CA associated with nuclear complexes in HeLa-derived cells and primary T cells consistent with a complete capsid and showed that treatment with the small molecule inhibitor PF74 did not result in capsid dissociation from nuclear complexes. Cone-shaped objects detected in the nucleus by electron tomography were clearly identified as capsid-derived structures by correlative microscopy. High-resolution imaging revealed dose-dependent clustering of nuclear capsids, suggesting that incoming particles may follow common entry routes.
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5
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Liang Y, Furukawa H, Sakamoto K, Inaba H, Matsuura K. Anticancer Activity of Reconstituted Ribonuclease S-Decorated Artificial Viral Capsid. Chembiochem 2022; 23:e202200220. [PMID: 35676201 PMCID: PMC9400862 DOI: 10.1002/cbic.202200220] [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: 04/24/2022] [Revised: 05/31/2022] [Indexed: 11/10/2022]
Abstract
Ribonuclease S (RNase S) is an enzyme that exhibits anticancer activity by degrading RNAs within cancer cells; however, the cellular uptake efficiency is low due to its small molecular size. Here we generated RNase S‐decorated artificial viral capsids with a size of 70–170 nm by self‐assembly of the β‐annulus‐S‐peptide followed by reconstitution with S‐protein at neutral pH. The RNase S‐decorated artificial viral capsids are efficiently taken up by HepG2 cells and exhibit higher RNA degradation activity in cells compared with RNase S alone. Cell viability assays revealed that RNase S‐decorated capsids have high anticancer activity comparable to that of standard anticancer drugs.
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Affiliation(s)
- Yingbing Liang
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Koyama-Minami 4-101, Tottori, 680-8552, Japan
| | - Hiroto Furukawa
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Koyama-Minami 4-101, Tottori, 680-8552, Japan
| | - Kentarou Sakamoto
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Koyama-Minami 4-101, Tottori, 680-8552, Japan
| | - Hiroshi Inaba
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Koyama-Minami 4-101, Tottori, 680-8552, Japan.,Centre for Research on Green Sustainable Chemistry, Tottori University, Koyama-Minami 4-101, Tottori, 680-8552, Japan
| | - Kazunori Matsuura
- Department of Chemistry and Biotechnology, Graduate School of Engineering, Tottori University, Koyama-Minami 4-101, Tottori, 680-8552, Japan.,Centre for Research on Green Sustainable Chemistry, Tottori University, Koyama-Minami 4-101, Tottori, 680-8552, Japan
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6
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Karsten L, Goett-Zink L, Schmitz J, Hoffrogge R, Grünberger A, Kottke T, Müller KM. Genetically Encoded Ratiometric pH Sensors for the Measurement of Intra- and Extracellular pH and Internalization Rates. BIOSENSORS 2022; 12:bios12050271. [PMID: 35624572 PMCID: PMC9138566 DOI: 10.3390/bios12050271] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/15/2022] [Revised: 04/04/2022] [Accepted: 04/11/2022] [Indexed: 12/13/2022]
Abstract
pH-sensitive fluorescent proteins as genetically encoded pH sensors are promising tools for monitoring intra- and extracellular pH. However, there is a lack of ratiometric pH sensors, which offer a good dynamic range and can be purified and applied extracellularly to investigate uptake. In our study, the bright fluorescent protein CoGFP_V0 was C-terminally fused to the ligand epidermal growth factor (EGF) and retained its dual-excitation and dual-emission properties as a purified protein. The tandem fluorescent variants EGF-CoGFP-mTagBFP2 (pK′ = 6.6) and EGF-CoGFP-mCRISPRed (pK′ = 6.1) revealed high dynamic ranges between pH 4.0 and 7.5. Using live-cell fluorescence microscopy, both pH sensor molecules permitted the conversion of fluorescence intensity ratios to detailed intracellular pH maps, which revealed pH gradients within endocytic vesicles. Additionally, extracellular binding of the pH sensors to cells expressing the EGF receptor (EGFR) enabled the tracking of pH shifts inside cultivation chambers of a microfluidic device. Furthermore, the dual-emission properties of EGF-CoGFP-mCRISPRed upon 488 nm excitation make this pH sensor a valuable tool for ratiometric flow cytometry. This high-throughput method allowed for the determination of internalization rates, which represents a promising kinetic parameter for the in vitro characterization of protein–drug conjugates in cancer therapy.
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Affiliation(s)
- Lennard Karsten
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Lukas Goett-Zink
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Julian Schmitz
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Raimund Hoffrogge
- Cell Culture Technology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
| | - Alexander Grünberger
- Multiscale Bioengineering, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany; (J.S.); (A.G.)
- Center for Biotechnology (CeBiTec), Bielefeld University, 33615 Bielefeld, Germany
| | - Tilman Kottke
- Biophysical Chemistry and Diagnostics, Medical School OWL, Faculty of Chemistry, Bielefeld University, 33615 Bielefeld, Germany; (L.G.-Z.); (T.K.)
| | - Kristian M. Müller
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany;
- Correspondence:
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7
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Kuklik J, Michelfelder S, Schiele F, Kreuz S, Lamla T, Müller P, Park JE. Development of a Bispecific Antibody-Based Platform for Retargeting of Capsid Modified AAV Vectors. Int J Mol Sci 2021; 22:ijms22158355. [PMID: 34361120 PMCID: PMC8347852 DOI: 10.3390/ijms22158355] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/09/2021] [Revised: 07/23/2021] [Accepted: 07/26/2021] [Indexed: 12/12/2022] Open
Abstract
A major limiting factor for systemically delivered gene therapies is the lack of novel tissue specific AAV (Adeno-associated virus) derived vectors. Bispecific antibodies can be used to redirect AAVs to specific target receptors. Here, we demonstrate that the insertion of a short linear epitope “2E3” derived from human proprotein-convertase subtilisin/kexin type 9 (PCSK9) into different surface loops of the VP capsid proteins can be used for AAV de-targeting from its natural receptor(s), combined with a bispecific antibody-mediated retargeting. We chose to target a set of distinct disease relevant membrane proteins—fibroblast activation protein (FAP), which is upregulated on activated fibroblasts within the tumor stroma and in fibrotic tissues, as well as programmed death-ligand 1 (PD-L1), which is strongly upregulated in many cancers. Upon incubation with a bispecific antibody recognizing the 2E3 epitope and FAP or PD-L1, the bispecific antibody/rAAV complex was able to selectively transduce receptor positive cells. In summary, we developed a novel, rationally designed vector retargeting platform that can target AAVs to a new set of cellular receptors in a modular fashion. This versatile platform may serve as a valuable tool to investigate the role of disease relevant cell types and basis for novel gene therapy approaches.
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Affiliation(s)
- Juliane Kuklik
- Division of Cancer Immunology and Immune Modulation, Boehringer Ingelheim Pharma GmbH & Co. KG, 88387 Biberach an der Riss, Germany;
| | - Stefan Michelfelder
- Division of Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, 88387 Biberach an der Riss, Germany; (S.M.); (S.K.)
| | - Felix Schiele
- Division of Biotherapeutics Discovery, Boehringer Ingelheim Pharma GmbH & Co. KG, 88387 Biberach an der Riss, Germany;
| | - Sebastian Kreuz
- Division of Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, 88387 Biberach an der Riss, Germany; (S.M.); (S.K.)
- Boehringer Ingelheim Venture Fund GmbH, 55216 Ingelheim am Rhein, Germany;
| | - Thorsten Lamla
- Division of Drug Discovery Sciences Biberach, Boehringer Ingelheim Pharma GmbH & Co. KG, 88387 Biberach an der Riss, Germany;
| | - Philipp Müller
- Boehringer Ingelheim Venture Fund GmbH, 55216 Ingelheim am Rhein, Germany;
| | - John E. Park
- Division of Cancer Immunology and Immune Modulation, Boehringer Ingelheim Pharma GmbH & Co. KG, 88387 Biberach an der Riss, Germany;
- Correspondence:
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8
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Wagner HJ, Weber W, Fussenegger M. Synthetic Biology: Emerging Concepts to Design and Advance Adeno-Associated Viral Vectors for Gene Therapy. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2021; 8:2004018. [PMID: 33977059 PMCID: PMC8097373 DOI: 10.1002/advs.202004018] [Citation(s) in RCA: 25] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/20/2020] [Revised: 12/18/2020] [Indexed: 05/28/2023]
Abstract
Three recent approvals and over 100 ongoing clinical trials make adeno-associated virus (AAV)-based vectors the leading gene delivery vehicles in gene therapy. Pharmaceutical companies are investing in this small and nonpathogenic gene shuttle to increase the therapeutic portfolios within the coming years. This prospect of marking a new era in gene therapy has fostered both investigations of the fundamental AAV biology as well as engineering studies to enhance delivery vehicles. Driven by the high clinical potential, a new generation of synthetic-biologically engineered AAV vectors is on the rise. Concepts from synthetic biology enable the control and fine-tuning of vector function at different stages of cellular transduction and gene expression. It is anticipated that the emerging field of synthetic-biologically engineered AAV vectors can shape future gene therapeutic approaches and thus the design of tomorrow's gene delivery vectors. This review describes and discusses the recent trends in capsid and vector genome engineering, with particular emphasis on synthetic-biological approaches.
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Affiliation(s)
- Hanna J. Wagner
- Department of Biosystems Science and EngineeringETH ZurichMattenstrasse 26Basel4058Switzerland
- Faculty of BiologyUniversity of FreiburgSchänzlestraße 1Freiburg79104Germany
- Signalling Research Centres BIOSS and CIBSSUniversity of FreiburgSchänzlestraße 18Freiburg79104Germany
| | - Wilfried Weber
- Faculty of BiologyUniversity of FreiburgSchänzlestraße 1Freiburg79104Germany
- Signalling Research Centres BIOSS and CIBSSUniversity of FreiburgSchänzlestraße 18Freiburg79104Germany
| | - Martin Fussenegger
- Department of Biosystems Science and EngineeringETH ZurichMattenstrasse 26Basel4058Switzerland
- Faculty of ScienceUniversity of BaselKlingelbergstrasse 50Basel4056Switzerland
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9
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Radukic MT, Brandt D, Haak M, Müller KM, Kalinowski J. Nanopore sequencing of native adeno-associated virus (AAV) single-stranded DNA using a transposase-based rapid protocol. NAR Genom Bioinform 2020; 2:lqaa074. [PMID: 33575623 PMCID: PMC7671332 DOI: 10.1093/nargab/lqaa074] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/22/2020] [Revised: 08/06/2020] [Accepted: 09/21/2020] [Indexed: 12/14/2022] Open
Abstract
Next-generation sequencing of single-stranded DNA (ssDNA) enables transgene characterization of gene therapy vectors such as adeno-associated virus (AAV), but current library generation uses complicated and potentially biased second-strand synthesis. We report that libraries for nanopore sequencing of ssDNA can be conveniently created without second-strand synthesis using a transposase-based protocol. We show for bacteriophage M13 ssDNA that the MuA transposase has unexpected residual activity on ssDNA, explained in part by transposase action on transient double-stranded hairpins. In case of AAV, library creation is additionally aided by genome hybridization. We demonstrate the power of direct sequencing combined with nanopore long reads by characterizing AAV vector transgenes. Sequencing yielded reads up to full genome length, including GC-rich inverted terminal repeats. Unlike short-read techniques, single reads covered genome-genome and genome-contaminant fusions and other recombination events, whilst additionally providing information on epigenetic methylation. Single-nucleotide variants across the transgene cassette were revealed and secondary genome packaging signals were readily identified. Moreover, comparison of sequence abundance with quantitative polymerase chain reaction results demonstrated the technique's future potential for quantification of DNA impurities in AAV vector stocks. The findings promote direct nanopore sequencing as a fast and versatile platform for ssDNA characterization, such as AAV ssDNA in research and clinical settings.
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Affiliation(s)
- Marco T Radukic
- Faculty of Technology, Bielefeld University, D-33501 Bielefeld, Germany
| | - David Brandt
- Center for Biotechnology (CeBiTec), Bielefeld University, D-33501 Bielefeld, Germany
| | - Markus Haak
- Center for Biotechnology (CeBiTec), Bielefeld University, D-33501 Bielefeld, Germany
| | - Kristian M Müller
- Faculty of Technology, Bielefeld University, D-33501 Bielefeld, Germany
| | - Jörn Kalinowski
- Center for Biotechnology (CeBiTec), Bielefeld University, D-33501 Bielefeld, Germany
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10
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Xu Y, Guo P, Zhang J, Chrzanowski M, Chew H, Firrman JA, Sang N, Diao Y, Xiao W. Effects of Thermally Induced Configuration Changes on rAAV Genome's Enzymatic Accessibility. Mol Ther Methods Clin Dev 2020; 18:328-334. [PMID: 32671135 PMCID: PMC7338580 DOI: 10.1016/j.omtm.2020.06.005] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Accepted: 06/03/2020] [Indexed: 11/15/2022]
Abstract
Physical titers for recombinant adeno-associated viral (rAAV) vectors are measured by quantifying viral genomes. It is generally perceived that AAV virions disassemble and release DNA upon thermal treatment. Here, we present data on enzymatic accessibility of rAAV genomes when AAV virions were subjected to thermal treatment. For rAAV vectors with a normal genome size (≤4.7 kb), thermal treatment at 75°C-99°C allowed only ∼10% of genomes to be detectable by quantitative real-time PCR. In contrast, greater than 70% of AAV genomes can be detected under similar conditions for AAV vectors with an oversized genome (≥5.0 kb). The permeability of virions, as measured by ethidium bromide (EB) staining, was enhanced by thermal stimulation. These results suggest that in rAAV virions with standard-sized genomes, the capsid and DNA are close enough in proximity for heat-induced "crosslinking," which results in inaccessibility of vector DNA to enzymatic reactions. In contrast, rAAV vectors with oversized genomes release their DNA readily upon thermal treatment. These findings suggested that the spatial arrangement of capsid protein and DNA in AAV virions is genome-size dependent. These results provide a foundation for future improvement of vector assays, design, and applications.
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Affiliation(s)
- Yinxia Xu
- School of Biomedical Science, Huaqiao University, Quanzhou, China
| | - Ping Guo
- School of Biomedical Science, Huaqiao University, Quanzhou, China
| | - Junping Zhang
- Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202, USA
| | | | - Helen Chew
- Temple University Medical School, Philadelphia, PA 19140, USA
| | - Jenni A. Firrman
- United States Department of Agriculture, Agricultural Research Service, Eastern Regional Research Center, Wyndmoor, PA 19038, USA
| | - Nianli Sang
- Department of Biology, College of Arts and Sciences, Drexel University, Philadelphia, PA 19104, USA
| | - Yong Diao
- School of Biomedical Science, Huaqiao University, Quanzhou, China
| | - Weidong Xiao
- Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202, USA
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11
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Le DT, Radukic MT, Müller KM. Adeno-associated virus capsid protein expression in Escherichia coli and chemically defined capsid assembly. Sci Rep 2019; 9:18631. [PMID: 31819093 PMCID: PMC6901487 DOI: 10.1038/s41598-019-54928-y] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2019] [Accepted: 11/20/2019] [Indexed: 01/17/2023] Open
Abstract
Research and clinical applications of recombinant adeno-associated virus (rAAV) significantly increased in recent years alongside regulatory approvals of rAAV gene therapy products. To date, all rAAV vectors as well as AAV empty capsids are produced in eukaryotic cells. We explored a new route to generate AAV capsids with the aim to analyze capsid assembly in a chemically defined setting and pave the way for new production methods and applications based on AAV virus-like particles (VLPs). We generated these empty capsids by bacterial expression and subsequent concomitant protein refolding and VLP formation. AAV serotype 2 structural protein VP3 was expressed in Escherichia coli. VLPs formed as demonstrated by dynamic light scattering, atomic force microscopy, and ELISA. Furthermore, VLPs internalized into human HeLa cells. To extend the application range of the VLPs, we tested peptide insertions, at the genetic level, in a surface loop (amino acid position 587) or at the C-terminus of VP3 and these variants also formed VLPs. VLPs developed without assembly-activating protein (AAP), but adding purified recombinant AAP to the refolding process increased capsid yield. Our findings offer a new route to understand AAV assembly biology and open a toolbox for AAV production strategies that might enable capsid display for vaccination and matching of capsids with cargoes at large scale and low cost.
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Affiliation(s)
- Dinh To Le
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, Bielefeld, Germany
| | - Marco T Radukic
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, Bielefeld, Germany
| | - Kristian M Müller
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, Bielefeld, Germany.
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