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Srinivasan P, Canova CT, Sha S, Nguyen TNT, Joseph J, Sangerman J, Maloney AJ, Katsikis G, Ou RW, Hong MS, Ng J, Yuan A, Antov D, Song S, Chen W, Neufeld C, Wolfrum JM, Barone PW, Sinskey AJ, Springs SL, Braatz RD. Multidose transient transfection of human embryonic kidney 293 cells modulates recombinant adeno-associated virus2/5 Rep protein expression and influences the enrichment fraction of filled capsids. Biotechnol Bioeng 2024. [PMID: 39176568 DOI: 10.1002/bit.28828] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2024] [Revised: 07/04/2024] [Accepted: 08/04/2024] [Indexed: 08/24/2024]
Abstract
Recombinant adeno-associated virus (rAAV) is a commonly used in vivo gene therapy vector because of its nonpathogenicity, long-term transgene expression, broad tropism, and ability to transduce both dividing and nondividing cells. However, rAAV vector production via transient transfection of mammalian cells typically yields a low fraction of filled-to-total capsids (~1%-30% of total capsids produced). Analysis of our previously developed mechanistic model for rAAV2/5 production attributed these low fill fractions to a poorly coordinated timeline between capsid synthesis and viral DNA replication and the repression of later phase capsid formation by Rep proteins. Here, we extend the model by quantifying the expression dynamics of total Rep proteins and their influence on the key steps of rAAV2/5 production using a multiple dosing transfection of human embryonic kidney 293 (HEK293) cells. We report that the availability of preformed empty capsids and viral DNA copies per cell are not limiting to the capsid-filling reaction. However, optimal expression of Rep proteins (<240 ± 13 ag per cell) enables enrichment of the filled capsid population (>12% of total capsids/cell) upstream. Our analysis suggests increased enrichment of filled capsids via regulating the expression of Rep proteins is possible but at the expense of per cell capsid titer in a triple plasmid transfection. Our study reveals an intrinsic limitation of scaling rAAV2/5 vector genome (vg) production and underscores the need for approaches that allow for regulating the expression of Rep proteins to maximize vg titer per cell upstream.
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Affiliation(s)
- Prasanna Srinivasan
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Christopher T Canova
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Sha Sha
- Ultragenyx Pharmaceutical Inc., Novato, Cambridge, USA
| | | | - John Joseph
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jose Sangerman
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | | | | | - Rui Wen Ou
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Moo Sun Hong
- School of Chemical and Biological Engineering, Seoul National University, Seoul, Republic of Korea
| | - Jaclyn Ng
- Stanford University School of Medicine, Stanford, California, USA
| | - Arella Yuan
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Daniel Antov
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Sally Song
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Wenyu Chen
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Caleb Neufeld
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Jacqueline M Wolfrum
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Paul W Barone
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Anthony J Sinskey
- Department of Biology, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Stacy L Springs
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
| | - Richard D Braatz
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, USA
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2
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Słyk Ż, Stachowiak N, Małecki M. Recombinant Adeno-Associated Virus Vectors for Gene Therapy of the Central Nervous System: Delivery Routes and Clinical Aspects. Biomedicines 2024; 12:1523. [PMID: 39062095 PMCID: PMC11274884 DOI: 10.3390/biomedicines12071523] [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: 04/19/2024] [Revised: 06/23/2024] [Accepted: 07/03/2024] [Indexed: 07/28/2024] Open
Abstract
The Central Nervous System (CNS) is vulnerable to a range of diseases, including neurodegenerative and oncological conditions, which present significant treatment challenges. The blood-brain barrier (BBB) restricts molecule penetration, complicating the achievement of therapeutic concentrations in the CNS following systemic administration. Gene therapy using recombinant adeno-associated virus (rAAV) vectors emerges as a promising strategy for treating CNS diseases, demonstrated by the registration of six gene therapy products in the past six years and 87 ongoing clinical trials. This review explores the implementation of rAAV vectors in CNS disease treatment, emphasizing AAV biology and vector engineering. Various administration methods-such as intravenous, intrathecal, and intraparenchymal routes-and experimental approaches like intranasal and intramuscular administration are evaluated, discussing their advantages and limitations in different CNS contexts. Additionally, the review underscores the importance of optimizing therapeutic efficacy through the pharmacokinetics (PK) and pharmacodynamics (PD) of rAAV vectors. A comprehensive analysis of clinical trials reveals successes and challenges, including barriers to commercialization. This review provides insights into therapeutic strategies using rAAV vectors in neurological diseases and identifies areas requiring further research, particularly in optimizing rAAV PK/PD.
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Affiliation(s)
- Żaneta Słyk
- Department of Applied Pharmacy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
- Laboratory of Gene Therapy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
| | - Natalia Stachowiak
- Department of Applied Pharmacy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
| | - Maciej Małecki
- Department of Applied Pharmacy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
- Laboratory of Gene Therapy, Faculty of Pharmacy, Medical University of Warsaw, 02-091 Warsaw, Poland
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3
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Catalán-Tatjer D, Tzimou K, Nielsen LK, Lavado-García J. Unravelling the essential elements for recombinant adeno-associated virus (rAAV) production in animal cell-based platforms. Biotechnol Adv 2024; 73:108370. [PMID: 38692443 DOI: 10.1016/j.biotechadv.2024.108370] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2024] [Revised: 04/05/2024] [Accepted: 04/27/2024] [Indexed: 05/03/2024]
Abstract
Recombinant adeno-associated viruses (rAAVs) stand at the forefront of gene therapy applications, holding immense significance for their safe and efficient gene delivery capabilities. The constantly increasing and unmet demand for rAAVs underscores the need for a more comprehensive understanding of AAV biology and its impact on rAAV production. In this literature review, we delved into AAV biology and rAAV manufacturing bioprocesses, unravelling the functions and essentiality of proteins involved in rAAV production. We discuss the interconnections between these proteins and how they affect the choice of rAAV production platform. By addressing existing inconsistencies, literature gaps and limitations, this review aims to define a minimal set of genes that are essential for rAAV production, providing the potential to advance rAAV biomanufacturing, with a focus on minimizing the genetic load within rAAV-producing cells.
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Affiliation(s)
- David Catalán-Tatjer
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark
| | - Konstantina Tzimou
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark
| | - Lars K Nielsen
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark; Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Australia
| | - Jesús Lavado-García
- The Novo Nordisk Foundation Center for Biosustainability, Technical University of Denmark, Denmark.
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4
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Ye X, Hu Y, Qiu H, Li N. Probe capsid structure stability and dynamics of adeno-associated virus as an important viral vector for gene therapy by hydrogen-deuterium exchange-mass spectrometry. Protein Sci 2024; 33:e5074. [PMID: 38888268 PMCID: PMC11184576 DOI: 10.1002/pro.5074] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2024] [Revised: 04/14/2024] [Accepted: 05/25/2024] [Indexed: 06/20/2024]
Abstract
Adeno-associated virus (AAV), a widely used gene therapy vector, is a small, nonenveloped virus that contains a single-stranded DNA genome with a maximum length of 4.7 kb. Despite extensive biophysical and structural characterization, many aspects of AAV functions remain elusive. This knowledge gap is primarily due to a lack of structurally resolved dynamic information and the absence of structural coverage of functionally critical segments on the AAV capsid. Here, we developed a protocol to study AAV structural dynamics by hydrogen-deuterium exchange mass spectrometry (HDX-MS), a powerful method for monitoring protein structure stability and dynamics in solution. We performed HDX-MS measurements on AAVs without or with different DNA payloads of different sizes, and obtained detailed dynamic information on the entire AAV sequence including the two functionally important segments not previously structurally characterized. The unique N terminus of the capsid protein VP1 (VP1u) was found to adopt a highly dynamic and unstable conformation with low HDX protection across the entire region, whereas the presence of a DNA payload increased its protection. The VP1 and VP2 shared region (VP1/2) showed no measurable protection, with or without DNA. Differential HDX between empty and full capsid samples allowed us to identify potential new DNA-capsid interaction sites located primarily around the five-fold channel, which differ from the three-fold pocket binding site previously identified. Our HDX-MS method for characterizing AAV structural dynamics opens a new way for future efforts to understand AAV structure-function relationships and engineer next-generation AAV vectors with improved gene delivery properties.
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Affiliation(s)
- Xiang Ye
- Regeneron Pharmaceuticals, Inc.TarrytownNew YorkUSA
| | - Yunli Hu
- Regeneron Pharmaceuticals, Inc.TarrytownNew YorkUSA
| | - Haibo Qiu
- Regeneron Pharmaceuticals, Inc.TarrytownNew YorkUSA
| | - Ning Li
- Regeneron Pharmaceuticals, Inc.TarrytownNew YorkUSA
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5
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Lin YC, Lu M, Cai W, Hu WS. Comparative transcriptomic and proteomic kinetic analysis of adeno-associated virus production systems. Appl Microbiol Biotechnol 2024; 108:385. [PMID: 38896252 PMCID: PMC11186941 DOI: 10.1007/s00253-024-13203-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/29/2024] [Revised: 05/20/2024] [Accepted: 05/23/2024] [Indexed: 06/21/2024]
Abstract
Recombinant adeno-associated virus (rAAV) is a major gene delivery vehicle. We have constructed a stable rAAV producer cell line by integrating essential rAAV genome, viral and helper genes into the genome of HEK293 cell under the control of inducible promoters. Upon induction, the cell line produces transducing rAAV. To gain insight into enhancing rAAV productivity and vector quality, we performed a comparative transcriptomic and proteomic analysis of our synthetic cell line GX2 and two wild-type AAV (wtAAV) production systems, one by virus co-infection and the other by multi-plasmid transfection. The three systems had different kinetics in viral component synthesis but generated comparable copies of AAV genomes; however, the capsid titer of GX2 was an order of magnitude lower compared to those two wtAAV systems, indicating that its capsid production may be insufficient. The genome packaging efficiency was also lower in GX2 despite it produced higher levels of Rep52 proteins than either wtAAV systems, suggesting that Rep52 protein expression may not limit genome packaging. In the two wtAAV systems, VP were the most abundant AAV proteins and their levels continued to increase, while GX2 had high level of wasteful cargo gene expression. Furthermore, upregulated inflammation, innate immune responses, and MAPK signaling, as well as downregulated mitochondrial functions, were commonly observed in either rAAV or wtAAV systems. Overall, this comparative multi-omics study provided rich insights into host cell and viral factors that are potential targets for genetic and process intervention to enhance the productivity of synthetic rAAV producer cell lines. KEY POINTS: • wtAAV infection was more efficient in producing full viral particles than the synthetic cell GX2. • Capsid protein synthesis, genome replication, and packaging may limit rAAV production in GX2. • wtAAV infection and rAAV production in GX2 elicited similar host cell responses.
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Affiliation(s)
- Yu-Chieh Lin
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue S.E, Minneapolis, MN, 55455-0132, USA
| | - Min Lu
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue S.E, Minneapolis, MN, 55455-0132, USA
| | - Wen Cai
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue S.E, Minneapolis, MN, 55455-0132, USA
| | - Wei-Shou Hu
- Department of Chemical Engineering and Materials Science, University of Minnesota, 421 Washington Avenue S.E, Minneapolis, MN, 55455-0132, USA.
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6
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Johari YB, Pohle TH, Whitehead J, Scarrott JM, Liu P, Mayer A, James DC. Molecular design of controllable recombinant adeno-associated virus (AAV) expression systems for enhanced vector production. Biotechnol J 2024; 19:e2300685. [PMID: 38900035 DOI: 10.1002/biot.202300685] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 05/28/2024] [Accepted: 05/31/2024] [Indexed: 06/21/2024]
Abstract
Recombinant adeno-associated virus (rAAV) is the leading vector for the delivery of gene therapies. However, low viral genome (VG) titers are common and the proportion of "full" capsids containing the therapeutic gene payload can be highly variable. The coordinated molecular design of plasmids encoding viral components and Helper functions remains a major challenge for rAAV manufacturing. Here we present the design of improved Rep/Cap and Helper plasmids for rAAV2/8 production, (i) a Rep/Cap expression vector harboring independently controllable rep and cap genes and (ii) an improved Helper plasmid harboring E4 gene deletion variants. First, an optimized Rep/Cap vector utilized a truncated p5 promoter, a p5 cis-regulatory element at the 3' end in combination with a heterologous promoter to drive Cap expression and an additional copy of the rep52/40 gene to overexpress short Rep proteins. We demonstrate that Rep78 is essential for efficient rAAV2/8 production in HEK293 cells, and a higher ratio of short Rep to long Rep proteins enhances genome packaging. Second, we identified regulators and open reading frames within the Helper plasmid that contribute to increased rAAV2/8 production. While L4-33k/22k is integral to optimal production, the use of E4orf6-6/7 subset significantly enhanced VG titer. Together, an optimal combination of engineered Rep/Cap and Helper plasmid variants increased VG titer by 3.1-fold. This study demonstrates that configuring and controlling the expression of the different AAV genetic elements contributes toward high rAAV production and product quality (full/empty capsid ratio).
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Affiliation(s)
- Yusuf B Johari
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - Thilo H Pohle
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
- Syngensys Ltd., Sheffield, UK
| | - Jared Whitehead
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - Joseph M Scarrott
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
| | - Ping Liu
- Cell Line Development, REGENXBIO Inc., Rockville, Maryland, USA
| | - Ayda Mayer
- Cell Line Development, REGENXBIO Inc., Rockville, Maryland, USA
| | - David C James
- Department of Chemical and Biological Engineering, University of Sheffield, Sheffield, UK
- Syngensys Ltd., Sheffield, UK
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7
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Jaiswal R, Santosh V, Braud B, Washington A, Escalante CR. Cryo-EM Structure of AAV2 Rep68 bound to integration site AAVS1: Insights into the mechanism of DNA melting. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.04.02.587759. [PMID: 38617369 PMCID: PMC11014581 DOI: 10.1101/2024.04.02.587759] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 04/16/2024]
Abstract
The Rep68 protein from Adeno-Associated Virus (AAV) is a multifunctional SF3 helicase that performs most of the DNA transactions required for the viral life cycle. During AAV DNA replication, Rep68 assembles at the origin and catalyzes the DNA melting and nicking reactions during the hairpin rolling replication process to complete the second-strand synthesis of the AAV genome. Here, we report the Cryo-EM structures of Rep68 bound to double-stranded DNA (dsDNA) containing the sequence of the AAVS1 integration site in different nucleotide-bound states. In the apo state, Rep68 forms a heptameric complex around DNA, with three Origin Binding Domains (OBDs) bound to the Rep Binding Site (RBS) sequence and three other OBDs forming transient dimers with them. The AAA+ domains form an open ring with no interactions between subunits and with DNA. We hypothesize the heptameric quaternary structure is necessary to load onto dsDNA. In the ATPγS-bound state, a subset of three subunits binds the nucleotide, undergoing a large conformational change, inducing the formation of intersubunit interactions interaction and interaction with three consecutive DNA phosphate groups. Moreover, the induced conformational change positions three phenylalanine residues to come in close contact with the DNA backbone, producing a distortion in the DNA. We propose that the phenylalanine residues can potentially act as a hydrophobic wedge in the DNA melting process.
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Affiliation(s)
- R. Jaiswal
- Department of Physiology and Biophysics, Virginia Commonwealth University, School of Medicine, Richmond VA, 23298
- Current address: Department of Biochemistry and Molecular Biology, University of Arkansas for the Medical Sciences, Little Rock AR 72205
| | - V. Santosh
- Department of Physiology and Biophysics, Virginia Commonwealth University, School of Medicine, Richmond VA, 23298
- Current address: US Army DEVCOM Chemical Biological Center, Gunpowder MD
| | - B. Braud
- Department of Physiology and Biophysics, Virginia Commonwealth University, School of Medicine, Richmond VA, 23298
| | - A. Washington
- Department of Physiology and Biophysics, Virginia Commonwealth University, School of Medicine, Richmond VA, 23298
- Current address: Mayo Clinic Graduate School of Biomedical Research, Department of Biochemistry and Molecular Biology, Rochester, MN 55905
| | - Carlos R. Escalante
- Department of Physiology and Biophysics, Virginia Commonwealth University, School of Medicine, Richmond VA, 23298
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8
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Zhao Y, Liu W, Li Y, Ma J, Liu T, Cui H, Deng Y, Liao X, Wang Z. Human Bocavirus 1 NP1 acts as an ssDNA-binding protein to help AAV2 DNA replication and cooperates with RPA to regulate AAV2 capsid expression. J Virol 2024; 98:e0151523. [PMID: 38323812 PMCID: PMC10949510 DOI: 10.1128/jvi.01515-23] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2023] [Accepted: 01/14/2024] [Indexed: 02/08/2024] Open
Abstract
Adeno-associated virus (AAV) requires co-infection with helper virus for efficient replication. We previously reported that Human Bocavirus 1 (HBoV1) genes, including NP1, NS2, and BocaSR, were critical for AAV2 replication. Here, we first demonstrate the essential roles of the NP1 protein in AAV2 DNA replication and protein expression. We show that NP1 binds to single-strand DNA (ssDNA) at least 30 nucleotides (nt) in length in a sequence-independent manner. Furthermore, NP1 colocalized with the BrdU-labeled AAV2 DNA replication center, and the loss of the ssDNA-binding ability of NP1 by site-directed mutation completely abolished AAV2 DNA replication. We used affinity-tagged NP1 protein to identify host cellular proteins associated with NP1 in cells cotransfected with the HBoV1 helper genes and AAV2 duplex genome. Of the identified proteins, we demonstrate that NP1 directly binds to the DBD-F domain of the RPA70 subunit with a high affinity through the residues 101-121. By reconstituting the heterotrimer protein RPA in vitro using gel filtration, we demonstrate that NP1 physically associates with RPA to form a heterologous complex characterized by typical fast-on/fast-off kinetics. Following a dominant-negative strategy, we found that NP1-RPA complex mainly plays a role in expressing AAV2 capsid protein by enhancing the transcriptional activity of the p40 promoter. Our study revealed a novel mechanism by which HBoV1 NP1 protein supports AAV2 DNA replication and capsid protein expression through its ssDNA-binding ability and direct interaction with RPA, respectively.IMPORTANCERecombinant adeno-associated virus (rAAV) vectors have been extensively used in clinical gene therapy strategies. However, a limitation of these gene therapy strategies is the efficient production of the required vectors, as AAV alone is replication-deficient in the host cells. HBoV1 provides the simplest AAV2 helper genes consisting of NP1, NS2, and BocaSR. An important question regarding the helper function of HBoV1 is whether it provides any direct function that supports AAV2 DNA replication and protein expression. Also of interest is how HBoV1 interplays with potential host factors to constitute a permissive environment for AAV2 replication. Our studies revealed that the multifunctional protein NP1 plays important roles in AAV2 DNA replication via its sequence-independent ssDNA-binding ability and in regulating AAV2 capsid protein expression by physically interacting with host protein RPA. Our findings present theoretical guidance for the future application of the HBoV1 helper genes in the rAAV vector production.
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Affiliation(s)
- Yanqun Zhao
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Wei Liu
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Yanjie Li
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Jing Ma
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Ting Liu
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Huichan Cui
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Yongheng Deng
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Xiaochen Liao
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
| | - Zekun Wang
- Joint National Laboratory for Antibody Drug Engineering, The First Affiliated Hospital, Henan University, Kaifeng, Henan, China
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Zhang J, Yu X, Chrzanowski M, Tian J, Pouchnik D, Guo P, Herzog RW, Xiao W. Thorough molecular configuration analysis of noncanonical AAV genomes in AAV vector preparations. Mol Ther Methods Clin Dev 2024; 32:101215. [PMID: 38463141 PMCID: PMC10924063 DOI: 10.1016/j.omtm.2024.101215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/30/2023] [Accepted: 02/16/2024] [Indexed: 03/12/2024]
Abstract
The unique palindromic inverted terminal repeats (ITRs) and single-stranded nature of adeno-associated virus (AAV) DNA are major hurdles to current sequencing technologies. Due to these characteristics, sequencing noncanonical AAV genomes present in AAV vector preparations remains challenging. To address this limitation, we developed thorough molecule configuration analysis of noncanonical AAV genomes (TMCA-AAV-seq). TMCA-AAV-seq takes advantage of the documented AAV packaging mechanism in which encapsidation initiates from its 3' ITR, for AAV-seq library construction. Any AAV genome with a 3' ITR is converted to a template suitable to adapter addition by a Bst DNA polymerase-mediated extension reaction. This extension reaction helps fix ITR heterogeneity in the AAV population and allows efficient adapter addition to even noncanonical AAV genomes. The resulting library maintains the original AAV genome configurations without introducing undesired changes. Subsequently, long-read sequencing can be performed by the Pacific Biosciences (PacBio) single-molecule, real-time (SMRT) sequencing technology platform. Finally, through comprehensive data analysis, we can recover canonical, noncanonical AAV DNA, and non-AAV vector DNA sequences, along with their molecular configurations. Our method is a robust tool for profiling thorough AAV-population genomes. TMCA-AAVseq can be further extended to all parvoviruses and their derivative vectors.
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Affiliation(s)
- Junping Zhang
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | | | - Jiahe Tian
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Derek Pouchnik
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164-4660, USA
| | - Ping Guo
- Lewis Katz School of Medicine, Temple University, Philadelphia, PA 19140, USA
| | - Roland W. Herzog
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Weidong Xiao
- Herman B Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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Zhang J, Frabutt DA, Chrzanowski M, Li N, Miller LM, Tian J, Mulcrone PL, Lam AK, Draper BE, Jarrold MF, Herzog RW, Xiao W. A novel class of self-complementary AAV vectors with multiple advantages based on cceAAV lacking mutant ITR. Mol Ther Methods Clin Dev 2024; 32:101206. [PMID: 38390555 PMCID: PMC10881427 DOI: 10.1016/j.omtm.2024.101206] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 01/30/2024] [Indexed: 02/24/2024]
Abstract
Self-complementary AAV vectors (scAAV) use a mutant inverted terminal repeat (mITR) for efficient packaging of complementary stranded DNA, enabling rapid transgene expression. However, inefficient resolution at the mITR leads to the packaging of monomeric or subgenomic AAV genomes. These noncanonical particles reduce transgene expression and may affect the safety of gene transfer. To address these issues, we have developed a novel class of scAAV vectors called covalently closed-end double-stranded AAV (cceAAV) that eliminate the mITR resolution step during production. Instead of using a mutant ITR, we used a 56-bp recognition sequence of protelomerase (TelN) to covalently join the top and bottom strands, allowing the vector to be generated with just a single ITR. To produce cceAAV vectors, the vector plasmid is initially digested with TelN, purified, and then subjected to a standard triple-plasmid transfection protocol followed by traditional AAV vector purification procedures. Such cceAAV vectors demonstrate yields comparable to scAAV vectors. Notably, we observed enhanced transgene expression as compared to traditional scAAV vectors. The treatment of mice with hemophilia B with cceAAV-FIX resulted in significantly enhanced long-term FIX expression. The cceAAV vectors hold several advantages over scAAV vectors, potentially leading to the development of improved human gene therapy drugs.
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Affiliation(s)
- Junping Zhang
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Dylan A. Frabutt
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | - Ning Li
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | - Jiahe Tian
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY 14853, USA
| | - Patrick L. Mulcrone
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Anh K. Lam
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | | | - Martin F. Jarrold
- Chemistry Department, Indiana University, Bloomington, IN 47405, USA
| | - Roland W. Herzog
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
| | - Weidong Xiao
- Herman B. Wells Center for Pediatric Research, Indiana University School of Medicine, Indianapolis, IN 46202, USA
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11
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Lopez-Gordo E, Chamberlain K, Riyad JM, Kohlbrenner E, Weber T. Natural Adeno-Associated Virus Serotypes and Engineered Adeno-Associated Virus Capsid Variants: Tropism Differences and Mechanistic Insights. Viruses 2024; 16:442. [PMID: 38543807 PMCID: PMC10975205 DOI: 10.3390/v16030442] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2023] [Revised: 03/02/2024] [Accepted: 03/06/2024] [Indexed: 05/23/2024] Open
Abstract
Today, adeno-associated virus (AAV)-based vectors are arguably the most promising in vivo gene delivery vehicles for durable therapeutic gene expression. Advances in molecular engineering, high-throughput screening platforms, and computational techniques have resulted in a toolbox of capsid variants with enhanced performance over parental serotypes. Despite their considerable promise and emerging clinical success, there are still obstacles hindering their broader use, including limited transduction capabilities, tissue/cell type-specific tropism and penetration into tissues through anatomical barriers, off-target tissue biodistribution, intracellular degradation, immune recognition, and a lack of translatability from preclinical models to clinical settings. Here, we first describe the transduction mechanisms of natural AAV serotypes and explore the current understanding of the systemic and cellular hurdles to efficient transduction. We then outline progress in developing designer AAV capsid variants, highlighting the seminal discoveries of variants which can transduce the central nervous system upon systemic administration, and, to a lesser extent, discuss the targeting of the peripheral nervous system, eye, ear, lung, liver, heart, and skeletal muscle, emphasizing their tissue and cell specificity and translational promise. In particular, we dive deeper into the molecular mechanisms behind their enhanced properties, with a focus on their engagement with host cell receptors previously inaccessible to natural AAV serotypes. Finally, we summarize the main findings of our review and discuss future directions.
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12
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Wang Y, Fu Q, Park SY, Lee YS, Park SY, Lee DY, Yoon S. Decoding cellular mechanism of recombinant adeno-associated virus (rAAV) and engineering host-cell factories toward intensified viral vector manufacturing. Biotechnol Adv 2024; 71:108322. [PMID: 38336188 DOI: 10.1016/j.biotechadv.2024.108322] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2023] [Revised: 01/22/2024] [Accepted: 02/06/2024] [Indexed: 02/12/2024]
Abstract
Recombinant adeno-associated virus (rAAV) is one of the prominent gene delivery vehicles that has opened promising opportunities for novel gene therapeutic approaches. However, the current major viral vector production platform, triple transfection in mammalian cells, may not meet the increasing demand. Thus, it is highly required to understand production bottlenecks from the host cell perspective and engineer the cells to be more favorable and tolerant to viral vector production, thereby effectively enhancing rAAV manufacturing. In this review, we provided a comprehensive exploration of the intricate cellular process involved in rAAV production, encompassing various stages such as plasmid entry to the cytoplasm, plasmid trafficking and nuclear delivery, rAAV structural/non-structural protein expression, viral capsid assembly, genome replication, genome packaging, and rAAV release/secretion. The knowledge in the fundamental biology of host cells supporting viral replication as manufacturing factories or exhibiting defending behaviors against viral production is summarized for each stage. The control strategies from the perspectives of host cell and materials (e.g., AAV plasmids) are proposed as our insights based on the characterization of molecular features and our existing knowledge of the AAV viral life cycle, rAAV and other viral vector production in the Human embryonic kidney (HEK) cells.
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Affiliation(s)
- Yongdan Wang
- Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - Qiang Fu
- Department of Biomedical Engineering and Biotechnology, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - So Young Park
- Department of Pharmaceutical Sciences, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - Yong Suk Lee
- Department of Pharmaceutical Sciences, University of Massachusetts Lowell, Lowell, MA 01854, United States of America
| | - Seo-Young Park
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Dong-Yup Lee
- School of Chemical Engineering, Sungkyunkwan University, 2066 Seobu-ro, Jangan-gu, Suwon, Gyeonggi-do 16419, Republic of Korea
| | - Seongkyu Yoon
- Department of Chemical Engineering, University of Massachusetts Lowell, Lowell, MA 01854, United States of America.
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13
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Merten OW. Development of Stable Packaging and Producer Cell Lines for the Production of AAV Vectors. Microorganisms 2024; 12:384. [PMID: 38399788 PMCID: PMC10892526 DOI: 10.3390/microorganisms12020384] [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: 12/04/2023] [Revised: 01/22/2024] [Accepted: 02/08/2024] [Indexed: 02/25/2024] Open
Abstract
Today, recombinant adeno-associated virus (rAAV) vectors represent the vector systems which are mostly used for in vivo gene therapy for the treatment of rare and less-rare diseases. Although most of the past developments have been performed by using a transfection-based method and more than half of the authorized rAAV-based treatments are based on transfection process, the tendency is towards the use of stable inducible packaging and producer cell lines because their use is much more straightforward and leads in parallel to reduction in the overall manufacturing costs. This article presents the development of HeLa cell-based packaging/producer cell lines up to their use for large-scale rAAV vector production, the more recent development of HEK293-based packaging and producer cell lines, as well as of packaging cell lines based on the use of Sf9 cells. The production features are presented in brief (where available), including vector titer, specific productivity, and full-to-empty particle ratio.
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14
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Schieferecke AJ, Lee H, Chen A, Kilaru V, Krish Williams J, Schaffer DV. Evolving membrane-associated accessory protein variants for improved adeno-associated virus production. Mol Ther 2024; 32:340-351. [PMID: 38115579 PMCID: PMC10861973 DOI: 10.1016/j.ymthe.2023.12.015] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2023] [Revised: 10/14/2023] [Accepted: 12/14/2023] [Indexed: 12/21/2023] Open
Abstract
Manufacturing sufficient adeno-associated virus (AAV) to meet current and projected clinical needs is a significant hurdle to the growing gene therapy industry. The recently discovered membrane-associated accessory protein (MAAP) is encoded by an alternative open reading frame in the AAV cap gene that is found in all presently reported natural serotypes. Recent evidence has emerged supporting a functional role of MAAP in AAV egress, although the underlying mechanisms of MAAP function remain unknown. Here, we show that inactivation of MAAP from AAV2 by a single point mutation that is silent in the VP1 open reading frame (ORF) (AAV2-ΔMAAP) decreased exosome-associated and secreted vector genome production. We hypothesized that novel MAAP variants could be evolved to increase AAV production and thus subjected a library encoding over 1 × 106 MAAP protein variants to five rounds of packaging selection into the AAV2-ΔMAAP capsid. Between each successive packaging round, we observed a progressive increase in both overall titer and ratio of secreted vector genomes conferred by the bulk-selected MAAP library population. Next-generation sequencing uncovered enriched mutational features, and a resulting selected MAAP variant containing missense mutations and a frameshifted C-terminal domain increased overall GFP transgene packaging in AAV2, AAV6, and AAV9 capsids.
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Affiliation(s)
- Adam J Schieferecke
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Hyuncheol Lee
- California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Aleysha Chen
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Vindhya Kilaru
- Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA
| | - Justin Krish Williams
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA
| | - David V Schaffer
- Department of Molecular and Cell Biology, University of California, Berkeley, Berkeley, CA 94720, USA; California Institute for Quantitative Biosciences, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Bioengineering, University of California, Berkeley, Berkeley, CA 94720, USA; Department of Chemical and Biomolecular Engineering, University of California, Berkeley, Berkeley, CA 94720, USA; Helen Wills Neuroscience Institute, University of California, Berkeley, Berkeley, CA 94720, USA.
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15
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Lu M, Lee Z, Lin YC, Irfanullah I, Cai W, Hu WS. Enhancing the production of recombinant adeno-associated virus in synthetic cell lines through systematic characterization. Biotechnol Bioeng 2024; 121:341-354. [PMID: 37749931 DOI: 10.1002/bit.28562] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2023] [Revised: 09/13/2023] [Accepted: 09/14/2023] [Indexed: 09/27/2023]
Abstract
Recombinant adeno-associated virus (rAAV) is among the most commonly used in vivo gene delivery vehicles and has seen a number of successes in clinical application. Current manufacturing processes of rAAV employ multiple plasmid transfection or rely on virus infection and face challenges in scale-up. A synthetic biology approach was taken to generate stable cell lines with integrated genetic modules, which produced rAAV upon induction albeit at a low productivity. To identify potential factors that restrained the productivity, we systematically characterized virus production kinetics through targeted quantitative proteomics and various physical assays of viral components. We demonstrated that reducing the excessive expression of gene of interest by its conditional expression greatly increased the productivity of these synthetic cell lines. Further enhancement was gained by optimizing induction profiles and alleviating proteasomal degradation of viral capsid protein by the addition of proteasome inhibitors. Altogether, these enhancements brought the productivity close to traditional multiple plasmid transfection. The rAAV produced had comparable full particle contents as those produced by conventional transient plasmid transfection. The present work exemplified the versatility of our synthetic biology-based viral vector production platform and its potential for plasmid- and virus-free rAAV manufacturing.
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Affiliation(s)
- Min Lu
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
| | - Zion Lee
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
| | - Yu-Chieh Lin
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
| | - Ibrahim Irfanullah
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
| | - Wen Cai
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
| | - Wei-Shou Hu
- Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, Minnesota, USA
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16
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Li X, Miller LM, Chrzanowski M, Tian J, Jarrold MF, Herzog RW, Xiao W, Draper B, Zhang J. Quantitative analysis of preferential utilization of AAV ITR as the packaging terminal signal. Front Bioeng Biotechnol 2023; 11:1327433. [PMID: 38173872 PMCID: PMC10761532 DOI: 10.3389/fbioe.2023.1327433] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2023] [Accepted: 12/05/2023] [Indexed: 01/05/2024] Open
Abstract
Genetic engineering advances have led to recombinant adeno-associated virus (rAAV) becoming an invaluable tool for the development of effective gene therapies. The production of rAAV is susceptible to off-target heterogeneous packaging, the effects of which are still being understood. Here, rAAV vectors with four-genome lengths were produced using both adherent and suspension HEK293 cells to understand the 5'ITR termination. AAV8 vectors were produced from the human FVIII plasmid for a full-length cargo of 4,707 nucleotides with specific truncations, creating smaller genomes. Conventionally, rAAV is characterized by differentiating empty capsids from full capsids, but for this work, that description is incomplete. The small genomes in this study were characterized by charge detection-mass spectrometry (CD-MS). Using CD-MS, packaged genomes in the range conventionally attributed to partials were resolved and quantified. In addition, alkaline gels and qPCR were used to assess the identity of the packaged genomes. Together, these results showed a propensity for unit-length genomes to be encapsidated. Packaged genomes occurred as replication intermediates emanating from the 5'ITR, indicating that HEK293 cells prefer unit-length genomes as opposed to the 5'ITR termination and heterogeneous DNA packaging observed previously from Sf9 cell systems. As both manufacturing processes are used and continually assessed to produce clinical material, such an understanding will benefit rAAV design for basic research and gene therapy.
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Affiliation(s)
- Xin Li
- Herman B Wells Center for Pediatric Research, Indiana University IUSM, Indianapolis, IN, United States
| | | | | | - Jiahe Tian
- Department of Molecular Biology and Genetics, Cornell University, Ithaca, NY, United States
| | - Martin F. Jarrold
- Chemistry Department, Indiana University, Bloomington, IN, United States
| | - Roland W. Herzog
- Herman B Wells Center for Pediatric Research, Indiana University IUSM, Indianapolis, IN, United States
| | - Weidong Xiao
- Herman B Wells Center for Pediatric Research, Indiana University IUSM, Indianapolis, IN, United States
| | | | - Junping Zhang
- Herman B Wells Center for Pediatric Research, Indiana University IUSM, Indianapolis, IN, United States
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17
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Hoffmann MD, Zdechlik AC, He Y, Nedrud D, Aslanidi G, Gordon W, Schmidt D. Multiparametric domain insertional profiling of adeno-associated virus VP1. Mol Ther Methods Clin Dev 2023; 31:101143. [PMID: 38027057 PMCID: PMC10661864 DOI: 10.1016/j.omtm.2023.101143] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2023] [Accepted: 10/21/2023] [Indexed: 12/01/2023]
Abstract
Several evolved properties of adeno-associated virus (AAV), such as broad tropism and immunogenicity in humans, are barriers to AAV-based gene therapy. Most efforts to re-engineer these properties have focused on variable regions near AAV's 3-fold protrusions and capsid protein termini. To comprehensively survey AAV capsids for engineerable hotspots, we determined multiple AAV fitness phenotypes upon insertion of six structured protein domains into the entire AAV-DJ capsid protein VP1. This is the largest and most comprehensive AAV domain insertion dataset to date. Our data revealed a surprising robustness of AAV capsids to accommodate large domain insertions. Insertion permissibility depended strongly on insertion position, domain type, and measured fitness phenotype, which clustered into contiguous structural units that we could link to distinct roles in AAV assembly, stability, and infectivity. We also identified engineerable hotspots of AAV that facilitate the covalent attachment of binding scaffolds, which may represent an alternative approach to re-direct AAV tropism.
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Affiliation(s)
- Mareike D. Hoffmann
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - Alina C. Zdechlik
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Yungui He
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
| | - David Nedrud
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | | | - Wendy Gordon
- Department of Biochemistry, Molecular Biology & Biophysics, University of Minnesota, Minneapolis, MN 55455, USA
| | - Daniel Schmidt
- Department of Genetics, Cell Biology & Development, University of Minnesota, Minneapolis, MN 55455, USA
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18
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Tejero M, Duzenli OF, Caine C, Kuoch H, Aslanidi G. Bioengineered Hybrid Rep 2/6 Gene Improves Encapsulation of a Single-Stranded Expression Cassette into AAV6 Vectors. Genes (Basel) 2023; 14:1866. [PMID: 37895215 PMCID: PMC10606878 DOI: 10.3390/genes14101866] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2023] [Revised: 09/18/2023] [Accepted: 09/21/2023] [Indexed: 10/29/2023] Open
Abstract
The production of clinical-grade recombinant adeno-associated viral (AAV) vectors for gene therapy trials remains a major hurdle in the further advancement of the gene therapy field. During the past decades, AAV research has been predominantly focused on the development of new capsid modifications, vector-associated immunogenicity, and the scale-up vector production. However, limited studies have examined the possibility to manipulate non-structural components of AAV such as the Rep genes. Historically, naturally isolated, or recombinant library-derived AAV capsids have been produced using the AAV serotype 2 Rep gene to package ITR2-flanked vector genomes. In the current study, we mutated four variable amino acids in the conservative part of the binding domain in AAV serotype 6 Rep to generate a Rep2/6 hybrid gene. This newly generated Rep2/6 hybrid had improved packaging ability over wild-type Rep6. AAV vectors produced with Rep2/6 exhibited similar in vivo activity as standard AAV6 vectors. Furthermore, we show that this Rep2/6 hybrid also improves full/empty capsid ratios, suggesting that Rep bioengineering can be used to improve the ratio of fully encapsulated AAV vectors during upstream manufacturing processes.
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Affiliation(s)
- Marcos Tejero
- Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55455, USA; (M.T.)
| | - Ozgun F. Duzenli
- Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55455, USA; (M.T.)
| | - Colin Caine
- Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55455, USA; (M.T.)
| | - Hisae Kuoch
- Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55455, USA; (M.T.)
| | - George Aslanidi
- Hormel Institute, University of Minnesota, 801 16th Avenue NE, Austin, MN 55455, USA; (M.T.)
- Masonic Cancer Center, University of Minnesota, Minneapolis, MN 55455, USA
- Institute Molecular Virology, University of Minnesota, Minneapolis, MN 55455, USA
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19
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Jalšić L, Lytvyn V, Elahi SM, Hrapovic S, Nassoury N, Chahal PS, Gaillet B, Gilbert R. Inducible HEK293 AAV packaging cell lines expressing Rep proteins. Mol Ther Methods Clin Dev 2023; 30:259-275. [PMID: 37560197 PMCID: PMC10407821 DOI: 10.1016/j.omtm.2023.07.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Accepted: 07/11/2023] [Indexed: 08/11/2023]
Abstract
Packaging or producer cell lines for scalable recombinant adeno-associated virus (rAAV) production have been notoriously difficult to create due in part to the cytostatic nature of the Rep proteins required for AAV production. The most difficult challenge being creating AAV packaging cell lines using HEK293 parental cells, currently the best mammalian platform for rAAV production due to the constitutive expression of E1A in HEK293 cells, a key REP transcription activator. Using suspension and serum-free media adapted HEK293SF carrying a gene expression regulation system induced by addition of cumate and coumermycin, we were able to create REP-expressing AAV packaging cells. This was achieved by carefully choosing two of the AAV Rep proteins (Rep 40 and 68), using two inducible promoters with different expression levels and integrating into the cells through lentiviral vector transduction. Three of our best clones produced rAAV titers comparable to titers obtained by standard triple plasmid transfection of their parental cells. These clones were stable for up to 7 weeks under continuous cultures condition. rAAV production from one clone was also validated at scale of 1 L in a wave bioreactor using serum-free suspension culture.
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Affiliation(s)
- Lovro Jalšić
- Département de Génie Chimique, Université Laval, Québec, QC G1V0A6, Canada
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Viktoria Lytvyn
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Seyyed Mehdy Elahi
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Sabahudin Hrapovic
- Advanced Biomaterials and Chemical Synthesis Team, Aquatic and Crop Resource Development Research Centre, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Nasha Nassoury
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Parminder Singh Chahal
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
| | - Bruno Gaillet
- Département de Génie Chimique, Université Laval, Québec, QC G1V0A6, Canada
| | - Rénald Gilbert
- Département de Génie Chimique, Université Laval, Québec, QC G1V0A6, Canada
- Department of Production Platforms and Analytics, Human Health Therapeutics Research Center, National Research Council Canada, Montréal, QC H4P 2R2, Canada
- Department of Bioengineering, McGill University, Montréal, QC H3A 0E9 Canada
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20
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Destro F, Joseph J, Srinivasan P, Kanter JM, Neufeld C, Wolfrum JM, Barone PW, Springs SL, Sinskey AJ, Cecchini S, Kotin RM, Braatz RD. Mechanistic modeling explains the production dynamics of recombinant adeno-associated virus with the baculovirus expression vector system. Mol Ther Methods Clin Dev 2023; 30:122-146. [PMID: 37746245 PMCID: PMC10512016 DOI: 10.1016/j.omtm.2023.05.019] [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: 02/04/2023] [Accepted: 05/30/2023] [Indexed: 09/26/2023]
Abstract
Current manufacturing processes for recombinant adeno-associated viruses (rAAVs) have less-than-desired yields and produce significant amounts of empty capsids. The increasing demand and the high cost of goods for rAAV-based gene therapies motivate development of more efficient manufacturing processes. Recently, the US Food and Drug Administration (FDA) approved the first rAAV-based gene therapy product manufactured in the baculovirus expression vector system (BEVS), a technology that demonstrated production of high titers of full capsids. This work presents a first mechanistic model describing the key extracellular and intracellular phenomena occurring during baculovirus infection and rAAV maturation in the BEVS. The model predictions are successfully validated for in-house and literature experimental measurements of the vector genome and of structural and non-structural proteins collected during rAAV manufacturing in the BEVS with the TwoBac and ThreeBac constructs. A model-based analysis of the process is carried out to identify the bottlenecks that limit full capsid formation. Vector genome amplification is found to be the limiting step for rAAV production in Sf9 cells using either the TwoBac or ThreeBac system. In turn, vector genome amplification is hindered by limiting Rep78 levels. Transgene and non-essential baculovirus protein expression in the insect cell during rAAV manufacturing also negatively influences the rAAV production yields.
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Affiliation(s)
- Francesco Destro
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - John Joseph
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Prasanna Srinivasan
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Joshua M. Kanter
- Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
| | - Caleb Neufeld
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Jacqueline M. Wolfrum
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Paul W. Barone
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Stacy L. Springs
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Anthony J. Sinskey
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Sylvain Cecchini
- Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
| | - Robert M. Kotin
- Gene Therapy Center, University of Massachusetts Chan Medical School, Worcester, MA 01655, USA
- Carbon Biosciences, Waltham, MA 02451, USA
| | - Richard D. Braatz
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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21
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Fu Q, Polanco A, Lee YS, Yoon S. Critical challenges and advances in recombinant adeno-associated virus (rAAV) biomanufacturing. Biotechnol Bioeng 2023; 120:2601-2621. [PMID: 37126355 DOI: 10.1002/bit.28412] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2023] [Revised: 03/27/2023] [Accepted: 04/19/2023] [Indexed: 05/02/2023]
Abstract
Gene therapy is a promising therapeutic approach for genetic and acquired diseases nowadays. Among DNA delivery vectors, recombinant adeno-associated virus (rAAV) is one of the most effective and safest vectors used in commercial drugs and clinical trials. However, the current yield of rAAV biomanufacturing lags behind the necessary dosages for clinical and commercial use, which embodies a concentrated reflection of low productivity of rAAV from host cells, difficult scalability of the rAAV-producing bioprocess, and high levels of impurities materialized during production. Those issues directly impact the price of gene therapy medicine in the market, limiting most patients' access to gene therapy. In this context, the current practices and several critical challenges associated with rAAV gene therapy bioprocesses are reviewed, followed by a discussion of recent advances in rAAV-mediated gene therapy and other therapeutic biological fields that could improve biomanufacturing if these advances are integrated effectively into the current systems. This review aims to provide the current state-of-the-art technology and perspectives to enhance the productivity of rAAV while reducing impurities during production of rAAV.
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Affiliation(s)
- Qiang Fu
- Department of Biomedical Engineering and Biotechnology, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Ashli Polanco
- Department of Chemical Engineering, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Yong Suk Lee
- Department of Pharmaceutical Sciences, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
| | - Seongkyu Yoon
- Department of Chemical Engineering, The University of Massachusetts Lowell, Lowell, Massachusetts, USA
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22
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Golm SK, Hübner W, Müller KM. Fluorescence Microscopy in Adeno-Associated Virus Research. Viruses 2023; 15:v15051174. [PMID: 37243260 DOI: 10.3390/v15051174] [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: 03/14/2023] [Revised: 05/02/2023] [Accepted: 05/07/2023] [Indexed: 05/28/2023] Open
Abstract
Research on adeno-associated virus (AAV) and its recombinant vectors as well as on fluorescence microscopy imaging is rapidly progressing driven by clinical applications and new technologies, respectively. The topics converge, since high and super-resolution microscopes facilitate the study of spatial and temporal aspects of cellular virus biology. Labeling methods also evolve and diversify. We review these interdisciplinary developments and provide information on the technologies used and the biological knowledge gained. The emphasis lies on the visualization of AAV proteins by chemical fluorophores, protein fusions and antibodies as well as on methods for the detection of adeno-associated viral DNA. We add a short overview of fluorescent microscope techniques and their advantages and challenges in detecting AAV.
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Affiliation(s)
- Susanne K Golm
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany
| | - Wolfgang Hübner
- Biomolecular Photonics, Faculty of Physics, Bielefeld University, 33615 Bielefeld, Germany
| | - Kristian M Müller
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany
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23
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Ning K, Kuz CA, Cheng F, Feng Z, Yan Z, Qiu J. Adeno-Associated Virus Monoinfection Induces a DNA Damage Response and DNA Repair That Contributes to Viral DNA Replication. mBio 2023; 14:e0352822. [PMID: 36719192 PMCID: PMC9973366 DOI: 10.1128/mbio.03528-22] [Citation(s) in RCA: 9] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2022] [Accepted: 01/03/2023] [Indexed: 02/01/2023] Open
Abstract
Adeno-associated virus (AAV) belongs to the Dependoparvovirus genus of the Parvoviridae family. AAV replication relies on a helper virus, such as adenovirus (Ad). Co-infection of AAV and Ad induces a DNA damage response (DDR), although its function in AAV DNA replication remains unknown. In this study, monoinfection of AAV2 in HEK293T cells expressing a minimal set of Ad helper genes was used to investigate the role of the DDR solely induced by AAV. We found that AAV2 DNA replication, but not single stranded (ss)DNA genome accumulation and Rep expression only, induced a robust DDR in HEK293T cells. The induced DDR featured the phosphorylation of replication protein A32 (RPA32), histone variant H2AX (H2A histone family member X), and all 3 phosphatidylinositol 3-kinase-related kinases (PIKKs). We also found that the kinase ataxia telangiectasia and Rad3-related protein (ATR) plays a major role in AAV2 DNA replication and that Y family DNA repair DNA polymerases η (Pol η) and Pol κ contribute to AAV2 DNA replication both in vitro and in HEK293T cells. Knockout of Pol η and Pol κ in HEK293T cells significantly decreased wild-type AAV2 replication and recombinant AAV2 production. Thus, our study has proven that AAV2 DNA replication induces a DDR, which in turn initiates a DNA repairing process that partially contributes to the viral genome amplification in HEK293T cells. IMPORTANCE Recombinant AAV (rAAV) has emerged as one of the preferred delivery vectors for clinical gene therapy. rAAV production in HEK293 cells by transfection of a rAAV transgene plasmid, an AAV Rep and Cap expression packaging plasmid, and an Ad helper plasmid remains the popular method. Here, we demonstrated that the high fidelity Y family DNA repair DNA polymerase, Pol η, and Pol κ, plays a significant role in AAV DNA replication and rAAV production in HEK293T cells. Understanding the AAV DNA replication mechanism in HEK293T cells could provide clues to increase rAAV vector yield produced from the transfection method. We also provide evidence that the ATR-mediated DNA repair process through Pol η and Pol κ is one of the mechanisms to amplify AAV genome, which could explain AAV replication and rAAV ssDNA genome conversion in mitotic quiescent cells.
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Affiliation(s)
- Kang Ning
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Cagla Aksu Kuz
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Fang Cheng
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
| | - Zehua Feng
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, USA
| | - Ziying Yan
- Department of Anatomy and Cell Biology, University of Iowa, Iowa City, Iowa, USA
| | - Jianming Qiu
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, Kansas, USA
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24
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Le DT, Radukic MT, Teschner K, Becker L, Müller KM. Synthesis and Concomitant Assembly of Adeno-Associated Virus-like Particles in Escherichia coli. ACS Synth Biol 2022; 11:3601-3607. [PMID: 36279242 DOI: 10.1021/acssynbio.2c00451] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
Virus-like particles (VLPs) have been used for numerous pharmaceutical applications, particularly vaccination and drug delivery. Recombinant adeno-associated virus (rAAV), a leading candidate in gene therapy, has been proposed as a vaccine scaffold, but high production costs limit its use. Here we establish intracellular production of AAV VLPs in Escherichia coli. VP3 capsid proteins of AAV serotype 5 (AAV5) were expressed, and VLPs were readily purified. The correct assembly was confirmed by ELISA with an intact-capsid AAV5 antibody and an AAVR domain as well as by atomic force microscopy. Biological functionality was demonstrated with a HeLa cell internalization assay. Coexpression of the assembly-activating protein (AAP) of AAV5 in E. coli improved capsid yield. This work provides the first evidence that AAV VLPs form in E. coli, opening new opportunities for production and exploration of AAV VLPs for biomedical applications.
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Affiliation(s)
- Dinh To Le
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany
| | - Marco T Radukic
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany
| | - Kathrin Teschner
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany
| | - Lukas Becker
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany
| | - Kristian M Müller
- Cellular and Molecular Biotechnology, Faculty of Technology, Bielefeld University, 33615 Bielefeld, Germany
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25
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Suoranta T, Laham-Karam N, Ylä-Herttuala S. Strategies to improve safety profile of AAV vectors. FRONTIERS IN MOLECULAR MEDICINE 2022; 2:1054069. [PMID: 39086961 PMCID: PMC11285686 DOI: 10.3389/fmmed.2022.1054069] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/26/2022] [Accepted: 10/17/2022] [Indexed: 08/02/2024]
Abstract
Adeno-associated virus (AAV) vectors are currently used in four approved gene therapies for Leber congenital amaurosis (Luxturna), spinal muscular atrophy (Zolgensma), aromatic L-amino acid decarboxylase deficiency (Upstaza) and Haemophilia A (Roctavian), with several more therapies being investigated in clinical trials. AAV gene therapy has long been considered extremely safe both in the context of immunotoxicity and genotoxicity, but recent tragic deaths in the clinical trials for X-linked myotubular myopathy and Duchenne's muscular dystrophy, together with increasing reports of potential hepatic oncogenicity in animal models have prompted re-evaluation of how much trust we can place on the safety of AAV gene therapy, especially at high doses. In this review we cover genome and capsid engineering strategies that can be used to improve safety of the next generation AAV vectors both in the context of immunogenicity and genotoxicity and discuss the gaps that need filling in our current knowledge about AAV vectors.
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Affiliation(s)
- Tuisku Suoranta
- A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Nihay Laham-Karam
- A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Seppo Ylä-Herttuala
- A. I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
- Heart Center, Kuopio University Hospital, Kuopio, Finland
- Gene Therapy Unit, Kuopio University Hospital, Kuopio, Finland
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26
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Arriaga I, Navarro A, Etxabe A, Trigueros C, Samulski RJ, Moullier P, François A, Abrescia NGA. Cellular and Structural Characterization of VP1 and VP2 Knockout Mutants of AAV3B Serotype and Implications for AAV Manufacturing. Hum Gene Ther 2022; 33:1142-1156. [PMID: 36082996 DOI: 10.1089/hum.2022.119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
AAV virion biology is still lacking a complete understanding of the role that the various structural subunits (VP1, 2, and 3) play in virus assembly, infectivity, and therapeutic delivery for clinical indications. In this study, we focus on the less studied adeno-associated virus AAV3B and generate a collection of AAV plasmid substrates that assemble virion particles deficient specifically in VP1, VP2, or VP1 and 2 structural subunits. Using a collection of biological and structural assays, we observed that virions devoid of VP1, VP2, or VP1 and 2 efficiently assembled virion particles, indistinguishable by cryoelectron microscopy (cryo-EM) from that of wild type (WT), but unique in virion transduction (WT > VP2 > VP1 > VP1 and 2 mutants). We also observed that the missing structural subunit was mostly compensated by additional VP3 protomers in the formed virion particle. Using cryo-EM analysis, virions fell into three classes, namely full, empty, and partially filled, based on comparison of density values within the capsid. Further, we characterize virions described as "broken" or "disassembled" particles, and provide structural information that supports the particle dissolution occurring through the two-fold symmetry sites. Finally, we highlight the unique value of employing cryo-EM as an essential tool for release criteria with respect to AAV manufacturing.
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Affiliation(s)
- Iker Arriaga
- Structure and Cell Biology of Viruses Lab, CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Derio, Spain
| | | | | | | | - R Jude Samulski
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | | | | | - Nicola G A Abrescia
- Structure and Cell Biology of Viruses Lab, CIC bioGUNE, Basque Research and Technology Alliance (BRTA), Derio, Spain.,Ikerbasque, Basque Foundation for Science, Bilbao, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Hepáticas y Digestivas (CIBERehd), Instituto de Salud Carlos III, Madrid, Spain
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27
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Lee Z, Lu M, Irfanullah E, Soukup M, Hu WS. Construction of an rAAV Producer Cell Line through Synthetic Biology. ACS Synth Biol 2022; 11:3285-3295. [PMID: 36219557 PMCID: PMC9595119 DOI: 10.1021/acssynbio.2c00207] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2022] [Indexed: 01/24/2023]
Abstract
Recombinant adeno-associated viruses (rAAV) are important gene delivery vehicles for gene therapy applications. Their production relies on plasmid transfection or virus infection of producer cells, which pose a challenge in process scale-up. Here, we describe a template for a transfection-free, helper virus-free rAAV producer cell line using a synthetic biology approach. Three modules were integrated into HEK293 cells including an rAAV genome and multiple inducible promoters controlling the expression of AAV Rep, Cap, and helper coding sequences. The synthetic cell line generated infectious rAAV vectors upon induction. Independent control over replication and packaging activities allowed for manipulation of the fraction of capsid particles containing viral genomes, affirming the feasibility of tuning gene expression profiles in a synthetic cell line for enhancing the quality of the viral vector produced. The synthetic biology approach for rAAV production presented in this study can be exploited for scalable biomanufacturing.
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Affiliation(s)
| | | | - Eesha Irfanullah
- Department of Chemical Engineering
and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Morgan Soukup
- Department of Chemical Engineering
and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
| | - Wei-Shou Hu
- Department of Chemical Engineering
and Materials Science, University of Minnesota, Minneapolis, Minnesota 55455, United States
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28
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Abstract
Adeno-associated virus (AAV) has a single-stranded DNA genome encapsidated in a small icosahedrally symmetric protein shell with 60 subunits. AAV is the leading delivery vector in emerging gene therapy treatments for inherited disorders, so its structure and molecular interactions with human hosts are of intense interest. A wide array of electron microscopic approaches have been used to visualize the virus and its complexes, depending on the scientific question, technology available, and amenability of the sample. Approaches range from subvolume tomographic analyses of complexes with large and flexible host proteins to detailed analysis of atomic interactions within the virus and with small ligands at resolutions as high as 1.6 Å. Analyses have led to the reclassification of glycan receptors as attachment factors, to structures with a new-found receptor protein, to identification of the epitopes of antibodies, and a new understanding of possible neutralization mechanisms. AAV is now well-enough characterized that it has also become a model system for EM methods development. Heralding a new era, cryo-EM is now also being deployed as an analytic tool in the process development and production quality control of high value pharmaceutical biologics, namely AAV vectors.
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Affiliation(s)
- Scott
M. Stagg
- Department
of Biological Sciences, Florida State University, Tallahassee, Florida 32306, United States
- Institute
of Molecular Biophysics, Florida State University, Tallahassee, Florida 32306, United States
| | - Craig Yoshioka
- Department
of Biomedical Engineering, Oregon Health
& Science University, Portland Oregon 97239, United States
| | - Omar Davulcu
- Environmental
Molecular Sciences Laboratory, Pacific Northwest
National Laboratory, 3335 Innovation Boulevard, Richland, Washington 99354, United States
| | - Michael S. Chapman
- Department
of Biochemistry, University of Missouri, Columbia, Missouri 65211, United States
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29
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Abstract
Viruses are obligate intracellular parasites. Despite their dependence on host cells, viruses are evolutionarily autonomous, with their own genomes and evolutionary trajectories locked in arms races with the hosts. Here, we discuss a simple functional logic to explain virus macroevolution that appears to define the course of virus evolution. A small core of virus hallmark genes that are responsible for genome replication apparently descended from primordial replicators, whereas most virus genes, starting with those encoding capsid proteins, were subsequently acquired from hosts. The oldest of these acquisitions antedate the last universal cellular ancestor (LUCA). Host gene capture followed two major routes: convergent recruitment of genes with functions that directly benefit virus reproduction and exaptation when host proteins are repurposed for unique virus functions. These forms of host protein recruitment by viruses result in different levels of similarity between virus and host homologs, with the exapted ones often changing beyond easy recognition.
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Affiliation(s)
- Eugene V Koonin
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA.
| | - Valerian V Dolja
- National Center for Biotechnology Information, National Library of Medicine, Bethesda, MD 20894, USA; Department of Botany and Plant Pathology, Oregon State University, Corvallis, OR 97331, USA
| | - Mart Krupovic
- Institut Pasteur, Université Paris Cité, CNRS UMR6047, Archaeal Virology Unit, F-75015 Paris, France.
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30
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Pan X, Yue Y, Boftsi M, Wasala LP, Tran NT, Zhang K, Pintel DJ, Tai PWL, Duan D. Rational engineering of a functional CpG-free ITR for AAV gene therapy. Gene Ther 2022; 29:333-345. [PMID: 34611321 PMCID: PMC8983793 DOI: 10.1038/s41434-021-00296-0] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Revised: 09/10/2021] [Accepted: 09/15/2021] [Indexed: 12/12/2022]
Abstract
Inverted terminal repeats (ITRs) are the only wild-type components retained in the genome of adeno-associated virus (AAV) vectors. To determine whether ITR modification is a viable approach for AAV vector engineering, we rationally deleted all CpG motifs in the ITR and examined whether CpG elimination compromises AAV-vector production and transduction. Modified ITRs were stable in the plasmid and maintained the CpG-free nature in purified vectors. Replacing the wild-type ITR with the CpG-free ITR did not affect vector genome encapsidation. However, the vector yield was decreased by approximately 3-fold due to reduced vector genome replication. To study the biological potency, we made micro-dystrophin (μDys) AAV vectors carrying either the wild-type ITR or the CpG-free ITR. We delivered the CpG-free μDys vector to one side of the tibialis anterior muscle of dystrophin-null mdx mice and the wild-type μDys vector to the contralateral side. Evaluation at four months after injection showed no difference in the vector genome copy number, microdystrophin expression, and muscle histology and force. Our results suggest that the complete elimination of the CpG motif in the ITR does not affect the biological activity of the AAV vector. CpG-free ITRs could be useful in engineering therapeutic AAV vectors.
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Affiliation(s)
- Xiufang Pan
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA
| | - Yongping Yue
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA
| | - Maria Boftsi
- Pathobiology Area Graduate Program, University of Missouri, Columbia, MO, 65212, USA
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65212, USA
| | - Lakmini P Wasala
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA
- Pathobiology Area Graduate Program, University of Missouri, Columbia, MO, 65212, USA
| | - Ngoc Tam Tran
- Horae Gene Therapy Center, UMass Chan Medical School, Worcester, MA, 01605, USA
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, MA, 01605, USA
| | - Keqing Zhang
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA
| | - David J Pintel
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA
- Christopher S. Bond Life Sciences Center, University of Missouri, Columbia, MO, 65212, USA
| | - Phillip W L Tai
- Horae Gene Therapy Center, UMass Chan Medical School, Worcester, MA, 01605, USA
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, MA, 01605, USA
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA.
- Department of Biomedical Sciences, College of Veterinary Medicine, University of Missouri, Columbia, MO, 65212, USA.
- Department of Neurology, School of Medicine, University of Missouri, Columbia, MO, 65212, USA.
- Department of Biomedical, Biological & Chemical Engineering, College of Engineering, University of Missouri, Columbia, MO, 65212, USA.
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31
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Xiao W, Samulski RJ. Recombinant Adeno-Associated Virus Production, the Beginning of the End of Uncertainty. Hum Gene Ther 2022; 33:355-357. [PMID: 35442070 DOI: 10.1089/hum.2022.29207.wxi] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Affiliation(s)
- Weidong Xiao
- Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, Indiana, USA
| | - R Jude Samulski
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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32
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Su W, Patrício MI, Duffy MR, Krakowiak JM, Seymour LW, Cawood R. Self-attenuating adenovirus enables production of recombinant adeno-associated virus for high manufacturing yield without contamination. Nat Commun 2022; 13:1182. [PMID: 35256603 PMCID: PMC8901928 DOI: 10.1038/s41467-022-28738-2] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/02/2021] [Accepted: 02/02/2022] [Indexed: 11/29/2022] Open
Abstract
Recombinant adeno-associated virus (rAAV) shows great promise for gene therapy, however scalability, yield and quality remain significant issues. Here we describe an rAAV manufacturing strategy using a 'helper' adenovirus that self-inhibits its major late promoter (MLP) to truncate its own replication. Inserting a tetracycline repressor (TetR) binding site into the MLP and encoding the TetR under its transcriptional control allowed normal adenovirus replication in the presence of doxycycline but only genome amplification and early gene expression (the 'helper' functions) in its absence. Using this self-inhibiting adenovirus we demonstrate delivery of adenoviral helper functions, AAV rep and cap genes, and the rAAV genome to yield up to 30-fold more rAAV vectors compared to the helper-free plasmid approach and significant improvements in particle infectivity for a range of serotypes. This system allows significant improvements in the production of serotypes rAAV2, rAAV6, rAAV8 and rAAV9, and enables propagation of existing rAAV without transfection, a process that improves batch quality by depleting reverse packaged DNA contaminants. We propose this as a high-yielding, contaminant-free system suitable for scalable rAAV manufacture.
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Affiliation(s)
- Weiheng Su
- Department of Oncology, University of Oxford, Old Road Campus, OX3 7DQ, Oxford, UK
- OXGENE Ltd, Oxford Science Park, OX4 4HG, Oxford, UK
| | | | - Margaret R Duffy
- Department of Oncology, University of Oxford, Old Road Campus, OX3 7DQ, Oxford, UK
| | | | - Leonard W Seymour
- Department of Oncology, University of Oxford, Old Road Campus, OX3 7DQ, Oxford, UK.
| | - Ryan Cawood
- OXGENE Ltd, Oxford Science Park, OX4 4HG, Oxford, UK
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33
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Kayukawa T, Yanagibashi A, Hongo‐Hirasaki T, Yanagida K. Particle‐based analysis elucidates the real retention capacities of virus filters and enables optimal virus clearance study design with evaluation systems of diverse virological characteristics. Biotechnol Prog 2022; 38:e3237. [PMID: 35064964 PMCID: PMC9285584 DOI: 10.1002/btpr.3237] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2021] [Revised: 01/17/2022] [Accepted: 01/19/2022] [Indexed: 11/08/2022]
Abstract
In virus clearance study (VCS) design, the amount of virus loaded onto the virus filters (VF) must be carefully controlled. A large amount of virus is required to demonstrate sufficient virus removal capability; however, too high a viral load causes virus breakthrough and reduces log reduction values. We have seen marked variation in the virus removal performance for VFs even with identical VCS design. Understanding how identical virus infectivity, materials and operating conditions can yield such different results is key to optimizing VCS design. The present study developed a particle number‐based method for VCS and investigated the effects on VF performance of discrepancies between apparent virus amount and total particle number of minute virus of mice. Co‐spiking of empty and genome‐containing particles resulted in a decrease in the virus removal performance proportional to the co‐spike ratio. This suggests that empty particles are captured in the same way as genome‐containing particles, competing for retention capacity. In addition, between virus titration methods with about 2.0 Log10 difference in particle‐to‐infectivity ratios, there was a 20‐fold decrease in virus retention capacity limiting the throughput that maintains the required LRV (e.g., 4.0), calculated using infectivity titers. These findings suggest that ignoring virus particle number in VCS design can cause virus overloading and accelerate filter breakthrough. This article asserts the importance of focusing on virus particle number and discusses optimization of VCS design that is unaffected by virological characteristics of evaluation systems and adequately reflect the VF retention capacity.
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Affiliation(s)
- Taiki Kayukawa
- Asahi Kasei Medical Co., Ltd., Medical Technology & Material Laboratory, Research and Business Development Division, Fuji Shizuoka JP
| | - Akiyo Yanagibashi
- Asahi Kasei Medical MT CORP., Bioprocess Technical Development Division, Nobeoka Miyazaki JP
| | | | - Koichiro Yanagida
- Asahi Kasei Medical Co., Ltd., Bioprocess Division Nobeoka Miyazaki JP
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34
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Overview of analytics needed to support a robust gene therapy manufacturing process. CURRENT OPINION IN BIOMEDICAL ENGINEERING 2021. [DOI: 10.1016/j.cobme.2021.100339] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
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35
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Galibert L, Hyvönen A, Eriksson RAE, Mattola S, Aho V, Salminen S, Albers JD, Peltola SK, Weman S, Nieminen T, Ylä-Herttuala S, Lesch HP, Vihinen-Ranta M, Airenne KJ. Functional roles of the membrane-associated AAV protein MAAP. Sci Rep 2021; 11:21698. [PMID: 34737404 PMCID: PMC8568889 DOI: 10.1038/s41598-021-01220-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Accepted: 10/25/2021] [Indexed: 12/23/2022] Open
Abstract
With a limited coding capacity of 4.7 kb, adeno-associated virus (AAV) genome has evolved over-lapping genes to maximise the usage of its genome. An example is the recently found ORF in the cap gene, encoding membrane-associated accessory protein (MAAP), located in the same genomic region as the VP1/2 unique domain, but in a different reading frame. This 13 KDa protein, unique to the dependovirus genus, is not homologous to any known protein. Our studies confirm that MAAP translation initiates from the first CTG codon found in the VP1 ORF2. We have further observed MAAP localised in the plasma membrane, in the membranous structures in close proximity to the nucleus and to the nuclear envelope by co-transfecting with plasmids encoding the wild-type AAV (wt-AAV) genome and adenovirus (Ad) helper genes. While keeping VP1/2 protein sequence identical, both inactivation and truncation of MAAP translation affected the emergence and intracellular distribution of the AAV capsid proteins. We have demonstrated that MAAP facilitates AAV replication and has a role in controlling Ad infection. Additionally, we were able to improve virus production and capsid integrity through a C-terminal truncation of MAAP while other modifications led to increased packaging of contaminating, non-viral DNA. Our results show that MAAP plays a significant role in AAV infection, with profound implications for the production of therapeutic AAV vectors.
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Affiliation(s)
| | - Amira Hyvönen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland ,grid.511728.8FinVector, Kuopio, Finland
| | - Reetta A. E. Eriksson
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland ,grid.9668.10000 0001 0726 2490A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland
| | - Salla Mattola
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
| | - Vesa Aho
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
| | - Sami Salminen
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
| | | | | | - Saija Weman
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Tiina Nieminen
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Seppo Ylä-Herttuala
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland ,grid.9668.10000 0001 0726 2490A.I. Virtanen Institute for Molecular Sciences, University of Eastern Finland, Kuopio, Finland ,grid.410705.70000 0004 0628 207XGene Therapy Unit and Research Center, Kuopio University Hospital, Kuopio, Finland
| | - Hanna P. Lesch
- Kuopio Center for Gene and Cell Therapy, Kuopio, Finland
| | - Maija Vihinen-Ranta
- grid.9681.60000 0001 1013 7965Department of Biological and Environmental Science and Nanoscience Center, University of Jyvaskyla, Jyväskylä, Finland
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36
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Boftsi M, Whittle FB, Wang J, Shepherd P, Burger LR, Kaifer KA, Lorson CL, Joshi T, Pintel DJ, Majumder K. The adeno-associated virus 2 (AAV2) genome and rep 68/78 proteins interact with cellular sites of DNA damage. Hum Mol Genet 2021; 31:985-998. [PMID: 34652429 DOI: 10.1093/hmg/ddab300] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/12/2021] [Revised: 09/20/2021] [Accepted: 10/11/2021] [Indexed: 12/14/2022] Open
Abstract
Nuclear DNA viruses simultaneously access cellular factors that aid their life cycle while evading inhibitory factors by localizing to distinct nuclear sites. Adeno-Associated Viruses (AAVs), which are Dependoviruses in the family Parvovirinae, are non-enveloped icosahedral viruses, that have been developed as recombinant AAV vectors (rAAV) to express transgenes. AAV2 expression and replication occur in nuclear viral replication centers (VRCs), which relies on cellular replication machinery as well as coinfection by helper viruses such as adenoviruses or herpesviruses, or exogenous DNA damage to host cells. AAV2 infection induces a complex cellular DNA damage response (DDR), either in response to viral DNA or viral proteins expressed in the host nucleus during infection, where VRCs colocalize with DDR proteins. We have previously developed a modified iteration of a viral chromosome conformation capture (V3C-seq) assay to show that the autonomous parvovirus Minute Virus of Mice (MVM) localizes to cellular sites of DNA damage to establish and amplify its replication. Similar V3C-seq assays to map AAV2 show that the AAV2 genome colocalized with cellular sites of DNA damage under both non-replicating and replicating conditions. The AAV2 non-structural protein Rep 68/78, also localized to cellular DDR sites during both non-replicating and replicating infections, and also when ectopically expressed. Ectopically expressed Rep could be efficiently re-localized to DDR sites induced by micro-irradiation. Recombinant AAV2 gene therapy vector genomes derived from AAV2 localized to sites of cellular DNA damage to a lesser degree, suggesting that the Inverted Terminal Repeat (ITR) origins of replication were insufficient for targeting.
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Affiliation(s)
- Maria Boftsi
- Pathobiology Area Graduate Program.,Christopher S. Bond Life Sciences Center
| | | | - Juexin Wang
- Christopher S. Bond Life Sciences Center.,Department of Electrical Engineering and Computer Science
| | | | | | - Kevin A Kaifer
- Christopher S. Bond Life Sciences Center.,Department of Veterinary Pathobiology, College of Veterinary Medicine
| | - Christian L Lorson
- Christopher S. Bond Life Sciences Center.,Department of Veterinary Pathobiology, College of Veterinary Medicine
| | - Trupti Joshi
- Christopher S. Bond Life Sciences Center.,Department of Electrical Engineering and Computer Science.,MU Informatics Institute.,Department of Health Management and Informatics
| | - David J Pintel
- Christopher S. Bond Life Sciences Center.,Molecular Microbiology and Immunology, University of Missouri-Columbia, School of Medicine, Columbia, MO USA 65211
| | - Kinjal Majumder
- Institute for Molecular Virology.,McArdle Laboratory for Cancer Research.,University of Wisconsin-Carbone Cancer Center
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Abstract
Redondoviridae is a newly established family of circular Rep-encoding single-stranded (CRESS) DNA viruses found in the human ororespiratory tract. Redondoviruses were previously found in ∼15% of respiratory specimens from U.S. urban subjects; levels were elevated in individuals with periodontitis or critical illness. Here, we report higher redondovirus prevalence in saliva samples: four rural African populations showed 61 to 82% prevalence, and an urban U.S. population showed 32% prevalence. Longitudinal, limiting-dilution single-genome sequencing revealed diverse strains of both redondovirus species (Brisavirus and Vientovirus) in single individuals, persistence over time, and evidence of intergenomic recombination. Computational analysis of viral genomes identified a recombination hot spot associated with a conserved potential DNA stem-loop structure. To assess the possible role of this site in recombination, we carried out in vitro studies which showed that this potential stem-loop was cleaved by the virus-encoded Rep protein. In addition, in reconstructed reactions, a Rep-DNA covalent intermediate was shown to mediate DNA strand transfer at this site. Thus, redondoviruses are highly prevalent in humans, found in individuals on multiple continents, heterogeneous even within individuals and encode a Rep protein implicated in facilitating recombination. IMPORTANCE Redondoviridae is a recently established family of DNA viruses predominantly found in the human respiratory tract and associated with multiple clinical conditions. In this study, we found high redondovirus prevalence in saliva from urban North American individuals and nonindustrialized African populations in Botswana, Cameroon, Ethiopia, and Tanzania. Individuals on both continents harbored both known redondovirus species. Global prevalence of both species suggests that redondoviruses have long been associated with humans but have remained undetected until recently due to their divergent genomes. By sequencing single redondovirus genomes in longitudinally sampled humans, we found that redondoviruses persisted over time within subjects and likely evolve by recombination. The Rep protein encoded by redondoviruses catalyzes multiple reactions in vitro, consistent with a role in mediating DNA replication and recombination. In summary, we identify high redondovirus prevalence in humans across multiple continents, longitudinal heterogeneity and persistence, and potential mechanisms of redondovirus evolution by recombination.
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38
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Phelps M, Balazs AB. Contribution to HIV Prevention and Treatment by Antibody-Mediated Effector Function and Advances in Broadly Neutralizing Antibody Delivery by Vectored Immunoprophylaxis. Front Immunol 2021; 12:734304. [PMID: 34603314 PMCID: PMC8479175 DOI: 10.3389/fimmu.2021.734304] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2021] [Accepted: 08/24/2021] [Indexed: 01/11/2023] Open
Abstract
HIV-1 broadly neutralizing antibodies (bNAbs) targeting the viral envelope have shown significant promise in both HIV prevention and viral clearance, including pivotal results against sensitive strains in the recent Antibody Mediated Prevention (AMP) trial. Studies of bNAb passive transfer in infected patients have demonstrated transient reduction of viral load at high concentrations that rebounds as bNAb is cleared from circulation. While neutralization is a crucial component of therapeutic efficacy, numerous studies have demonstrated that bNAbs can also mediate effector functions, such as antibody-dependent cellular cytotoxicity (ADCC), antibody-dependent cellular phagocytosis (ADCP), and antibody-dependent complement deposition (ADCD). These functions have been shown to contribute towards protection in several models of HIV acquisition and in viral clearance during chronic infection, however the role of target epitope in facilitating these functions, as well as the contribution of individual innate functions in protection and viral clearance remain areas of active investigation. Despite their potential, the transient nature of antibody passive transfer limits the widespread use of bNAbs. To overcome this, we and others have demonstrated vectored antibody delivery capable of yielding long-lasting expression of bNAbs in vivo. Two clinical trials have shown that adeno-associated virus (AAV) delivery of bNAbs is safe and capable of sustained bNAb expression for over 18 months following a single intramuscular administration. Here, we review key concepts of effector functions mediated by bNAbs against HIV infection and the potential for vectored immunoprophylaxis as a means of producing bNAbs in patients.
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Mietzsch M, Eddington C, Jose A, Hsi J, Chipman P, Henley T, Choudhry M, McKenna R, Agbandje-McKenna M. Improved Genome Packaging Efficiency of Adeno-associated Virus Vectors Using Rep Hybrids. J Virol 2021; 95:e0077321. [PMID: 34287038 PMCID: PMC8428402 DOI: 10.1128/jvi.00773-21] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 07/03/2021] [Indexed: 01/11/2023] Open
Abstract
Recombinant adeno-associated viruses (rAAVs) are one of the most commonly used vectors for a variety of gene therapy applications. In the last 2 decades, research focused primarily on the characterization and isolation of new cap, genes resulting in hundreds of natural and engineered AAV capsid variants, while the rep gene, the other major AAV open reading frame, has been less studied. This is due to the fact that the rep gene from AAV serotype 2 (AAV2) enables the single-stranded DNA packaging of recombinant genomes into most AAV serotype and engineered capsids. However, a major by-product of all vector productions is empty AAV capsids, lacking the encapsidated vector genome, especially for non-AAV2 vectors. Despite the packaging process being considered the rate-limiting step for rAAV production, none of the rep genes from the other AAV serotypes have been characterized for their packaging efficiency. Thus, in this study AAV2 rep was replaced with the rep gene of a select number of AAV serotypes. However, this led to a lowering of capsid protein expression, relative to the standard AAV2-rep system. In further experiments the 3' end of the AAV2 rep gene was reintroduced to promote increased capsid expression and a series of chimeras between the different AAV Rep proteins were generated and characterized for their vector genome packaging ability. The utilization of these novel Rep hybrids increased the percentage of genome containing (full) capsids approximately 2- to -4-fold for all of the non-AAV2 serotypes tested. Thus, these Rep chimeras could revolutionize rAAV production. IMPORTANCE A major by-product of all adeno-associated virus (AAV) vector production systems are "empty" capsids, void of the desired therapeutic gene, and thus do not provide any curative benefit for the treatment of the targeted disease. In fact, empty capsids can potentially elicit additional immune responses in vivo gene therapies if not removed by additional purification steps. Thus, there is a need to increase the genome packaging efficiency and reduce the number of empty capsids from AAV biologics. The novel Rep hybrids from different AAV serotypes described in this study are capable of reducing the percentage of empty capsids in all tested AAV serotypes and improve overall yields of genome-containing AAV capsids at the same time. They can likely be integrated easily into existing AAV manufacturing protocols to optimize the production of the generated AAV gene therapy products.
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Affiliation(s)
- Mario Mietzsch
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Courtnee Eddington
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Ariana Jose
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Jane Hsi
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Paul Chipman
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Tom Henley
- Intima Bioscience, New York, New York, USA
| | | | - Robert McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
| | - Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, Florida, USA
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40
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The Effects of Packaged, but Misguided, Single-Stranded DNA Genomes Are Transmitted to the Outer Surface of the ϕX174 Capsid. J Virol 2021; 95:e0088321. [PMID: 34232738 DOI: 10.1128/jvi.00883-21] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Most icosahedral viruses condense their genomes into volumetrically constrained capsids. However, concurrent genome biosynthesis and packaging are specific to single-stranded DNA (ssDNA) viruses. ssDNA genome packaging combines elements found in both double-stranded DNA (dsDNA) and ssRNA systems. Similar to dsDNA viruses, the genome is packaged into a preformed capsid. Like ssRNA viruses, there are numerous capsid-genome associations. In ssDNA microviruses, the DNA-binding protein J guides the genome between 60 icosahedrally ordered DNA binding pockets. It also partially neutralizes the DNA's negative phosphate backbone. ϕX174-related microviruses, such as G4 and α3, have J proteins that differ in length and charge organization. This suggests that interchanging J proteins could alter the path used to guide DNA in the capsid. Previously, a ϕXG4J chimera, in which the ϕX174 J gene was replaced with the G4 gene, was characterized. It displayed lethal packaging defects, which resulted in procapsids being removed from productive assembly. Here, we report the characterization of another inviable chimera, ϕXα3J. Unlike ϕXG4J, ϕXα3J efficiently packaged DNA but produced noninfectious particles. These particles displayed a reduced ability to attach to host cells, suggesting that internal DNA organization could distort the capsid's outer surface. Mutations that restored viability altered J-coat protein contact sites. These results provide evidence that the organization of ssDNA can affect both packaging and postpackaging phenomena. IMPORTANCE ssDNA viruses utilize icosahedrally ordered protein-nucleic acids interactions to guide and organize their genomes into preformed shells. As previously demonstrated, chaotic genome-capsid associations can inhibit ϕX174 packaging by destabilizing packaging complexes. However, the consequences of poorly organized genomes may extend beyond the packaging reaction. As demonstrated herein, it can lead to uninfectious packaged particles. Thus, ssDNA genomes should be considered an integral and structural virion component, affecting the properties of the entire particle, which includes the capsid's outer surface.
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41
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Monobac System-A Single Baculovirus for the Production of rAAV. Microorganisms 2021; 9:microorganisms9091799. [PMID: 34576695 PMCID: PMC8465638 DOI: 10.3390/microorganisms9091799] [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: 07/07/2021] [Revised: 08/09/2021] [Accepted: 08/13/2021] [Indexed: 11/28/2022] Open
Abstract
Large-scale manufacturing of rAAV is a bottleneck for the development of genetic disease treatments. The baculovirus/Sf9 cell system underpins the first rAAV treatment approved by EMA and remains one of the most advanced platforms for rAAV manufacturing. Despite early successes, rAAV is still a complex biomaterial to produce. Efficient production of the recombinant viral vector requires that AAV replicase and capsid genes be co-located with the recombinant AAV genome. Here, we present the Monobac system, a singular, modified baculovirus genome that contains all of these functions. To assess the relative yields between the dual baculovirus and Monobac systems, we prepared each system with a transgene encoding γSGC and evaluated vectors’ potency in vivo. Our results show that rAAV production using the Monobac system not only yields higher titers of rAAV vector but also a lower amount of DNA contamination from baculovirus.
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42
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Large EE, Silveria MA, Zane GM, Weerakoon O, Chapman MS. Adeno-Associated Virus (AAV) Gene Delivery: Dissecting Molecular Interactions upon Cell Entry. Viruses 2021; 13:1336. [PMID: 34372542 PMCID: PMC8310307 DOI: 10.3390/v13071336] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Revised: 07/08/2021] [Accepted: 07/08/2021] [Indexed: 12/13/2022] Open
Abstract
Human gene therapy has advanced from twentieth-century conception to twenty-first-century reality. The recombinant Adeno-Associated Virus (rAAV) is a major gene therapy vector. Research continues to improve rAAV safety and efficacy using a variety of AAV capsid modification strategies. Significant factors influencing rAAV transduction efficiency include neutralizing antibodies, attachment factor interactions and receptor binding. Advances in understanding the molecular interactions during rAAV cell entry combined with improved capsid modulation strategies will help guide the design and engineering of safer and more efficient rAAV gene therapy vectors.
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Affiliation(s)
| | | | | | | | - Michael S. Chapman
- Department of Biochemistry, University of Missouri, Columbia, MO 65201, USA; (E.E.L.); (M.A.S.); (G.M.Z.); (O.W.)
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43
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Zhang J, Yu X, Guo P, Firrman J, Pouchnik D, Diao Y, Samulski RJ, Xiao W. Satellite Subgenomic Particles Are Key Regulators of Adeno-Associated Virus Life Cycle. Viruses 2021; 13:v13061185. [PMID: 34205760 PMCID: PMC8235507 DOI: 10.3390/v13061185] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2021] [Revised: 06/16/2021] [Accepted: 06/17/2021] [Indexed: 11/22/2022] Open
Abstract
Historically, adeno-associated virus (AAV)-defective interfering particles (DI) were known as abnormal virions arising from natural replication and encapsidation errors. Through single virion genome analysis, we revealed that a major category of DI particles contains a double-stranded DNA genome in a “snapback” configuration. The 5′- snapback genomes (SBGs) include the P5 promoters and partial rep gene sequences. The 3′-SBGs contains the capsid region. The molecular configuration of 5′-SBGs theoretically may allow double-stranded RNA transcription in their dimer configuration. Our studies demonstrated that 5-SBG regulated AAV rep expression and improved AAV packaging. In contrast, 3′-SBGs at its dimer configuration increased levels of cap protein. The generation and accumulation of 5′-SBGs and 3′-SBGs appears to be coordinated to balance the viral gene expression level. Therefore, the functions of 5′-SBGs and 3′-SBGs may help maximize the yield of AAV progenies. We postulate that AAV virus population behaved as a colony and utilizes its subgenomic particles to overcome the size limit of a viral genome and encodes additional essential functions.
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Affiliation(s)
- Junping Zhang
- School of Medicine, Huaqiao University, Quanzhou 362021, China; (J.Z.); (X.Y.); (P.G.); (Y.D.)
| | - Xiangping Yu
- School of Medicine, Huaqiao University, Quanzhou 362021, China; (J.Z.); (X.Y.); (P.G.); (Y.D.)
| | - Ping Guo
- School of Medicine, Huaqiao University, Quanzhou 362021, China; (J.Z.); (X.Y.); (P.G.); (Y.D.)
| | - Jenni Firrman
- Dairy and Functional Foods Research Unit, Eastern Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, Wyndmoor, PA 19038, USA;
| | - Derek Pouchnik
- School of Molecular Biosciences, Washington State University, Pullman, WA 99164, USA;
| | - Yong Diao
- School of Medicine, Huaqiao University, Quanzhou 362021, China; (J.Z.); (X.Y.); (P.G.); (Y.D.)
| | - Richard Jude Samulski
- Department of Pharmacology, School of Medicine, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA
- Correspondence: (R.J.S.); (W.X.)
| | - Weidong Xiao
- Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202, USA
- Correspondence: (R.J.S.); (W.X.)
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44
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Shao L, Shen W, Wang S, Qiu J. Recent Advances in Molecular Biology of Human Bocavirus 1 and Its Applications. Front Microbiol 2021; 12:696604. [PMID: 34220786 PMCID: PMC8242256 DOI: 10.3389/fmicb.2021.696604] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2021] [Accepted: 05/12/2021] [Indexed: 11/25/2022] Open
Abstract
Human bocavirus 1 (HBoV1) was discovered in human nasopharyngeal specimens in 2005. It is an autonomous human parvovirus and causes acute respiratory tract infections in young children. HBoV1 infects well differentiated or polarized human airway epithelial cells in vitro. Unique among all parvoviruses, HBoV1 expresses 6 non-structural proteins, NS1, NS1-70, NS2, NS3, NS4, and NP1, and a viral non-coding RNA (BocaSR), and three structural proteins VP1, VP2, and VP3. The BocaSR is the first identified RNA polymerase III (Pol III) transcribed viral non-coding RNA in small DNA viruses. It plays an important role in regulation of viral gene expression and a direct role in viral DNA replication in the nucleus. HBoV1 genome replication in the polarized/non-dividing airway epithelial cells depends on the DNA damage and DNA repair pathways and involves error-free Y-family DNA repair DNA polymerase (Pol) η and Pol κ. Importantly, HBoV1 is a helper virus for the replication of dependoparvovirus, adeno-associated virus (AAV), in polarized human airway epithelial cells, and HBoV1 gene products support wild-type AAV replication and recombinant AAV (rAAV) production in human embryonic kidney (HEK) 293 cells. More importantly, the HBoV1 capsid is able to pseudopackage an rAAV2 or rHBoV1 genome, producing the rAAV2/HBoV1 or rHBoV1 vector. The HBoV1 capsid based rAAV vector has a high tropism for human airway epithelia. A deeper understanding in HBoV1 replication and gene expression will help find a better way to produce the rAAV vector and to increase the efficacy of gene delivery using the rAAV2/HBoV1 or rHBoV1 vector, in particular, to human airways. This review summarizes the recent advances in gene expression and replication of HBoV1, as well as the use of HBoV1 as a parvoviral vector for gene delivery.
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Affiliation(s)
- Liting Shao
- Beijing Institute of Radiation Medicine, Beijing, China
| | - Weiran Shen
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, United States
| | - Shengqi Wang
- Beijing Institute of Radiation Medicine, Beijing, China
| | - Jianming Qiu
- Department of Microbiology, Molecular Genetics and Immunology, University of Kansas Medical Center, Kansas City, KS, United States
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45
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Nguyen TN, Sha S, Hong MS, Maloney AJ, Barone PW, Neufeld C, Wolfrum J, Springs SL, Sinskey AJ, Braatz RD. Mechanistic model for production of recombinant adeno-associated virus via triple transfection of HEK293 cells. Mol Ther Methods Clin Dev 2021; 21:642-655. [PMID: 34095346 PMCID: PMC8143981 DOI: 10.1016/j.omtm.2021.04.006] [Citation(s) in RCA: 38] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2020] [Accepted: 04/08/2021] [Indexed: 02/08/2023]
Abstract
Manufacturing of recombinant adeno-associated virus (rAAV) viral vectors remains challenging, with low yields and low full:empty capsid ratios in the harvest. To elucidate the dynamics of recombinant viral production, we develop a mechanistic model for the synthesis of rAAV viral vectors by triple plasmid transfection based on the underlying biological processes derived from wild-type AAV. The model covers major steps starting from exogenous DNA delivery to the reaction cascade that forms viral proteins and DNA, which subsequently result in filled capsids, and the complex functions of the Rep protein as a regulator of the packaging plasmid gene expression and a catalyst for viral DNA packaging. We estimate kinetic parameters using dynamic data from literature and in-house triple transient transfection experiments. Model predictions of productivity changes as a result of the varied input plasmid ratio are benchmarked against transfection data from the literature. Sensitivity analysis suggests that (1) the poorly coordinated timeline of capsid synthesis and viral DNA replication results in a low ratio of full virions in harvest, and (2) repressive function of the Rep protein could be impeding capsid production at a later phase. The analyses from the mathematical model provide testable hypotheses for evaluation and reveal potential process bottlenecks that can be investigated.
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Affiliation(s)
- Tam N.T. Nguyen
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Sha Sha
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Moo Sun Hong
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Andrew J. Maloney
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Paul W. Barone
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Caleb Neufeld
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Jacqueline Wolfrum
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Stacy L. Springs
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Anthony J. Sinskey
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA, USA
- Department of Biology, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - Richard D. Braatz
- Department of Chemical Engineering, Massachusetts Institute of Technology, Cambridge, MA, USA
- Center for Biomedical Innovation, Massachusetts Institute of Technology, Cambridge, MA, USA
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46
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Earley LF, Conatser LM, Lue VM, Dobbins AL, Li C, Hirsch ML, Samulski RJ. Adeno-Associated Virus Serotype-Specific Inverted Terminal Repeat Sequence Role in Vector Transgene Expression. Hum Gene Ther 2021; 31:151-162. [PMID: 31914802 DOI: 10.1089/hum.2019.274] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Adeno-associated viral vectors have been successfully used in laboratory and clinical settings for efficient gene delivery. In these vectors, 96% of the adeno-associated virus (AAV) genome is replaced with a gene cassette of interest, leaving only the 145 bp inverted terminal repeat (ITR) sequences. These cis-elements, primarily from AAV serotype 2, are required for genome rescue, replication, packaging, and vector persistence. Previous work from our lab and others have demonstrated that the AAV ITR2 sequence has inherent transcriptional activity, which may confound intended transgene expression in therapeutic applications. Currently, AAV capsids are extensively study for vector contribution; however, a comprehensive analysis of ITR promoter activity of various AAV serotypes has not been described to date. Here, the transcriptional activity of AAV ITRs from different serotypes (1-4, 6, and 7) was compared in numerous cell lines and a mouse model. Under the conditions used here, all ITRs tested were capable of promoting transgene expression both in vitro and in vivo. However, we observed three classes of AAV ITR expression in vitro. Class I ITRs (AAV2 and 3) generated the highest level, whereas class II (AAV 4) had intermediate levels, and class III (AAV1 and 6) had the lowest levels. These expression levels were consistent across multiple cell lines. Only ITR7 demonstrated cell-type dependent transcriptional activity. In vivo, all classes had promoter activity. Next-generation sequencing revealed multiple transcriptional start sites that originated from the ITR sequence, with most arising from within the Rep binding element. The collective results demonstrate that the serotype ITR sequence may have multiple levels of influence on transgene expression cassettes independent of promoter selection.
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Affiliation(s)
- Lauriel F Earley
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina
| | - Laura M Conatser
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina.,Department of Ophthalmology, University of North Carolina, Chapel Hill, North Carolina
| | - Victoria M Lue
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina.,Department of Ophthalmology, University of North Carolina, Chapel Hill, North Carolina
| | - Amanda L Dobbins
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina
| | - Chengwen Li
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina.,Carolina Institute for Developmental Disabilities, University of North Carolina, Chapel Hill, North Carolina.,Department of Pediatrics, University of North Carolina, Chapel Hill, North Carolina
| | - Matthew L Hirsch
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina.,Department of Ophthalmology, University of North Carolina, Chapel Hill, North Carolina
| | - R Jude Samulski
- Gene Therapy Center, University of North Carolina, Chapel Hill, North Carolina.,Department of Pharmacology, University of North Carolina, Chapel Hill, North Carolina
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47
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Korneyenkov MA, Zamyatnin AA. Next Step in Gene Delivery: Modern Approaches and Further Perspectives of AAV Tropism Modification. Pharmaceutics 2021; 13:pharmaceutics13050750. [PMID: 34069541 PMCID: PMC8160765 DOI: 10.3390/pharmaceutics13050750] [Citation(s) in RCA: 23] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2021] [Revised: 05/14/2021] [Accepted: 05/17/2021] [Indexed: 11/16/2022] Open
Abstract
Today, adeno-associated virus (AAV) is an extremely popular choice for gene therapy delivery. The safety profile and simplicity of the genome organization are the decisive advantages which allow us to claim that AAV is currently among the most promising vectors. Several drugs based on AAV have been approved in the USA and Europe, but AAV serotypes’ unspecific tissue tropism is still a serious limitation. In recent decades, several techniques have been developed to overcome this barrier, such as the rational design, directed evolution and chemical conjugation of targeting molecules with a capsid. Today, all of the abovementioned approaches confer the possibility to produce AAV capsids with tailored tropism, but recent data indicate that a better understanding of AAV biology and the growth of structural data may theoretically constitute a rational approach to most effectively produce highly selective and targeted AAV capsids. However, while we are still far from this goal, other approaches are still in play, despite their drawbacks and limitations.
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Affiliation(s)
- Maxim A. Korneyenkov
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, 119991 Moscow, Russia;
| | - Andrey A. Zamyatnin
- Institute of Molecular Medicine, Sechenov First Moscow State Medical University, 119991 Moscow, Russia
- Department of Biotechnology, Sirius University of Science and Technology, 1 Olympic Ave, 354340 Sochi, Russia
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, 119992 Moscow, Russia
- Correspondence: ; Tel.: +7-495-622-9843
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Cellular pathways of recombinant adeno-associated virus production for gene therapy. Biotechnol Adv 2021; 49:107764. [PMID: 33957276 DOI: 10.1016/j.biotechadv.2021.107764] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2021] [Revised: 04/10/2021] [Accepted: 05/01/2021] [Indexed: 12/11/2022]
Abstract
Recombinant adeno-associated viruses (rAAVs) are among the most important vectors for in vivo gene therapies. With the rapid development of gene therapy, current rAAV manufacturing capacity faces a challenge to meet the emerging demand for these therapies in the future. To examine the bottlenecks in rAAV production during cell culture, we focus here on an analysis of cellular pathways of rAAV production, based on an overview of assembly mechanisms first in the wild-type (wt) AAV replication and then in the common methods of rAAV production. The differences analyzed between the wild-type and recombinant systems provide insights into the mechanistic differences that may correlate with viral productivity. Based on these analyses, we identify potential barriers to high productivity of rAAV and discuss future directions for improvement to meet the emerging needs set by the growth of rAAV-based therapy and the needs of patients.
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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: 26] [Impact Index Per Article: 8.7] [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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Joshi PRH, Venereo-Sanchez A, Chahal PS, Kamen AA. Advancements in molecular design and bioprocessing of recombinant adeno-associated virus gene delivery vectors using the insect-cell baculovirus expression platform. Biotechnol J 2021; 16:e2000021. [PMID: 33277815 DOI: 10.1002/biot.202000021] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2020] [Revised: 11/27/2020] [Indexed: 01/23/2023]
Abstract
Despite rapid progress in the field, scalable high-yield production of adeno-associated virus (AAV) is still one of the critical bottlenecks the manufacturing sector is facing. The insect cell-baculovirus expression vector system (IC-BEVS) has emerged as a mainstream platform for the scalable production of recombinant proteins with clinically approved products for human use. In this review, we provide a detailed overview of the advancements in IC-BEVS for rAAV production. Since the first report of baculovirus-induced production of rAAV vector in insect cells in 2002, this platform has undergone significant improvements, including enhanced stability of Bac-vector expression and a reduced number of baculovirus-coinfections. The latter streamlining strategy led to the eventual development of the Two-Bac, One-Bac, and Mono-Bac systems. The one baculovirus system consisting of an inducible packaging insect cell line was further improved to enhance the AAV vector quality and potency. In parallel, the implementation of advanced manufacturing approaches and control of critical processing parameters have demonstrated promising results with process validation in large-scale bioreactor runs. Moreover, optimization of the molecular design of vectors to enable higher cell-specific yields of functional AAV particles combined with bioprocess intensification strategies may also contribute to addressing current and future manufacturing challenges.
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Affiliation(s)
- Pranav R H Joshi
- Department of Bioengineering, McGill University, Montréal, Quebec, Canada
| | | | - Parminder S Chahal
- Human Health Therapeutics Portfolio, National Research Council of Canada, Montréal, Quebec, Canada
| | - Amine A Kamen
- Department of Bioengineering, McGill University, Montréal, Quebec, Canada
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