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Abstract
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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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2
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Meyer N, Davulcu O, Xie Q, Silveria M, Zane GM, Large E, Chapman MS. Expression and Purification of Adeno-associated Virus Virus-like Particles in a Baculovirus System and AAVR Ectodomain Constructs in E. coli. Bio Protoc 2020; 10:e3513. [PMID: 33654738 PMCID: PMC7842819 DOI: 10.21769/bioprotoc.3513] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 12/16/2019] [Accepted: 12/30/2019] [Indexed: 11/02/2022] Open
Abstract
Adeno-associated virus (AAV) is a promising gene therapy vector and the biophysical characterization of its interactions with host proteins is a critical foundation for engineering tissue targeting and immune escape. Presented here are protocols for the production of: (a) the outer protein shells (virus-like particles or VLPs) for serotype 2 (AAV-2) and (b) two fragments from the binding ectodomain of AAV's cellular receptor, AAVR. His6PKD1-2 comprises the first two polycystic kidney disease (PKD) domains, the minimal required for efficient binding of AAV, expressed with an N-terminal histidine tag. MBP-PKD1-5 is a fusion of the maltose binding protein with all five of the PKD domains of the AAVR receptor. Presented are the expression and purification of milligram quantities, ample for in vitro analyses. For AAV-2, the protocol offers an alternative to the use of (infectious) wild-type virus or transducing vectors. One of the methods for producing transducing vector is in Sf9 cells, and the production of VLPs is based on this. For AAVR, the protocols enable biochemical and biophysical characterization of virus-binding. The minimal two-domain construct allows more saturated binding to symmetry-equivalent sites on the virus, while the larger construct might be better expected to reflect the native receptor.
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Affiliation(s)
- Nancy Meyer
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, United States
- Pacific Northwest Cryo-EM Center, OHSU Center for Spatial Systems Biomedicine, Portland, United States
| | - Omar Davulcu
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, United States
- Pfizer, Chesterfield, United States
| | - Qing Xie
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, United States
- Department of Molecular and Medical Genetics, Oregon Health and Science University, Portland, United States
| | - Mark Silveria
- Department of Biochemistry, University of Missouri, Columbia, United States
| | - Grant M. Zane
- Department of Biochemistry, University of Missouri, Columbia, United States
| | - Edward Large
- Department of Biochemistry, University of Missouri, Columbia, United States
| | - Michael S. Chapman
- Department of Biochemistry and Molecular Biology, Oregon Health and Science University, Portland, United States
- Department of Biochemistry, University of Missouri, Columbia, United States
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3
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Lykken EA, Shyng C, Edwards RJ, Rozenberg A, Gray SJ. Recent progress and considerations for AAV gene therapies targeting the central nervous system. J Neurodev Disord 2018; 10:16. [PMID: 29776328 PMCID: PMC5960126 DOI: 10.1186/s11689-018-9234-0] [Citation(s) in RCA: 94] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/08/2018] [Accepted: 05/01/2018] [Indexed: 12/23/2022] Open
Abstract
BACKGROUND Neurodevelopmental disorders, as a class of diseases, have been particularly difficult to treat even when the underlying cause(s), such as genetic alterations, are understood. What treatments do exist are generally not curative and instead seek to improve quality of life for affected individuals. The advent of gene therapy via gene replacement offers the potential for transformative therapies to slow or even stop disease progression for current patients and perhaps minimize or prevent the appearance of symptoms in future patients. MAIN BODY This review focuses on adeno-associated virus (AAV) gene therapies for diseases of the central nervous system. An overview of advances in AAV vector design for therapy is provided, along with a description of current strategies to develop AAV vectors with tailored tropism. Next, progress towards treatment of neurodegenerative diseases is presented at both the pre-clinical and clinical stages, focusing on a few select diseases to highlight broad categories of therapeutic parameters. Special considerations for more challenging cases are then discussed in addition to the immunological aspects of gene therapy. CONCLUSION With the promising clinical trial results that have been observed for the latest AAV gene therapies and continued pre-clinical successes, the question is no longer whether a therapy can be developed for certain neurodevelopmental disorders, but rather, how quickly.
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Affiliation(s)
- Erik Allen Lykken
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
| | - Charles Shyng
- University of North Carolina at Chapel Hill, Gene Therapy Center, Chapel Hill, NC 27599 USA
| | - Reginald James Edwards
- University of North Carolina at Chapel Hill, Gene Therapy Center, Chapel Hill, NC 27599 USA
| | - Alejandra Rozenberg
- University of North Carolina at Chapel Hill, Gene Therapy Center, Chapel Hill, NC 27599 USA
| | - Steven James Gray
- Department of Pediatrics, University of Texas Southwestern Medical Center, Dallas, TX 75390 USA
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Nance ME, Duan D. Perspective on Adeno-Associated Virus Capsid Modification for Duchenne Muscular Dystrophy Gene Therapy. Hum Gene Ther 2015; 26:786-800. [PMID: 26414293 PMCID: PMC4692109 DOI: 10.1089/hum.2015.107] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2015] [Accepted: 09/01/2015] [Indexed: 12/19/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a X-linked, progressive childhood myopathy caused by mutations in the dystrophin gene, one of the largest genes in the genome. It is characterized by skeletal and cardiac muscle degeneration and dysfunction leading to cardiac and/or respiratory failure. Adeno-associated virus (AAV) is a highly promising gene therapy vector. AAV gene therapy has resulted in unprecedented clinical success for treating several inherited diseases. However, AAV gene therapy for DMD remains a significant challenge. Hurdles for AAV-mediated DMD gene therapy include the difficulty to package the full-length dystrophin coding sequence in an AAV vector, the necessity for whole-body gene delivery, the immune response to dystrophin and AAV capsid, and the species-specific barriers to translate from animal models to human patients. Capsid engineering aims at improving viral vector properties by rational design and/or forced evolution. In this review, we discuss how to use the state-of-the-art AAV capsid engineering technologies to overcome hurdles in AAV-based DMD gene therapy.
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MESH Headings
- Animals
- Capsid/chemistry
- Capsid/metabolism
- Capsid Proteins/genetics
- Capsid Proteins/metabolism
- Dependovirus/genetics
- Dependovirus/metabolism
- Dystrophin/deficiency
- Dystrophin/genetics
- Gene Expression
- Genetic Therapy/methods
- Genetic Vectors/chemistry
- Genetic Vectors/metabolism
- Humans
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscular Dystrophy, Animal/genetics
- Muscular Dystrophy, Animal/metabolism
- Muscular Dystrophy, Animal/pathology
- Muscular Dystrophy, Animal/therapy
- Muscular Dystrophy, Duchenne/genetics
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/pathology
- Muscular Dystrophy, Duchenne/therapy
- Mutation
- Protein Engineering
- Species Specificity
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Affiliation(s)
- Michael E. Nance
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, Missouri
| | - Dongsheng Duan
- Department of Molecular Microbiology and Immunology, School of Medicine, University of Missouri, Columbia, Missouri
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Salganik M, Hirsch ML, Samulski RJ. Adeno-associated Virus as a Mammalian DNA Vector. Microbiol Spectr 2015; 3:10.1128/microbiolspec.MDNA3-0052-2014. [PMID: 26350320 PMCID: PMC4677393 DOI: 10.1128/microbiolspec.mdna3-0052-2014] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Indexed: 12/20/2022] Open
Abstract
In the nearly five decades since its accidental discovery, adeno-associated virus (AAV) has emerged as a highly versatile vector system for both research and clinical applications. A broad range of natural serotypes, as well as an increasing number of capsid variants, has combined to produce a repertoire of vectors with different tissue tropisms, immunogenic profiles and transduction efficiencies. The story of AAV is one of continued progress and surprising discoveries in a viral system that, at first glance, is deceptively simple. This apparent simplicity has enabled the advancement of AAV into the clinic, where despite some challenges it has provided hope for patients and a promising new tool for physicians. Although a great deal of work remains to be done, both in studying the basic biology of AAV and in optimizing its clinical application, AAV vectors are currently the safest and most efficient platform for gene transfer in mammalian cells.
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Affiliation(s)
- Max Salganik
- Gene Therapy Center, Department of Pharmacology, University of North Carolina, Chapel Hill, NC
| | - Matthew L Hirsch
- Gene Therapy Center, Department of Pharmacology, University of North Carolina, Chapel Hill, NC
| | - Richard Jude Samulski
- Gene Therapy Center, Department of Pharmacology, University of North Carolina, Chapel Hill, NC
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Zhang F, Aguilera J, Beaudet JM, Xie Q, Lerch TF, Davulcu O, Colón W, Chapman MS, Linhardt RJ. Characterization of interactions between heparin/glycosaminoglycan and adeno-associated virus. Biochemistry 2013; 52:6275-85. [PMID: 23952613 PMCID: PMC3859860 DOI: 10.1021/bi4008676] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Adeno-associated virus (AAV) is a key candidate in the development of gene therapy. In this work, we used surface plasmon resonance spectroscopy to study the interaction between AAV and heparin and other glycosaminoglycans (GAGs). Surface plasmon resonance results revealed that heparin binds to AAV with an extremely high affinity. Solution competition studies showed that binding of AAV to heparin is chain length-dependent. AAV prefers to bind full chain heparin. All sulfo groups (especially N-sulfo and 6-O-sulfo groups) on heparin are important for the AAV-heparin interaction. Higher levels of sulfo group substitution in GAGs enhance their binding affinities. Atomic force microscopy was also performed to image AAV-2 in a complex with heparin.
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Affiliation(s)
- Fuming Zhang
- Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Javier Aguilera
- Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Julie M. Beaudet
- Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Qing Xie
- Department of Biochemistry and Molecular Biology School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Thomas F. Lerch
- Department of Biochemistry and Molecular Biology School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Omar Davulcu
- Department of Biochemistry and Molecular Biology School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Wilfredo Colón
- Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
| | - Michael S. Chapman
- Department of Biochemistry and Molecular Biology School of Medicine, Oregon Health & Science University, Portland, OR 97239, USA
| | - Robert J. Linhardt
- Department of Chemical and Biological Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
- Department of Chemistry and Chemical Biology, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
- Departments of Biology and Biomedical Engineering, Center for Biotechnology and Interdisciplinary Studies, Rensselaer Polytechnic Institute, Troy, NY 12180, USA
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Abstract
The Adeno-associated viruses (AAVs) are not associated with any diseases, and their ability to package non-genomic DNA and to transduce different cell/tissue populations has generated significant interest in understanding their basic biology in efforts to improve their utilization for corrective gene delivery. This includes their capsid structure, cellular tropism and interactions for entry, uncoating, replication, DNA packaging, capsid assembly, and antibody neutralization. The human and nonhuman primate AAVs are clustered into serologically distinct genetic clade and serotype groups, which have distinct cellular/tissue tropisms and transduction efficiencies. These properties are highly dependent upon the AAV capsid amino acid sequence, their capsid structure, and their interactions with host cell factors, including cell surface receptors, co-receptors, signaling molecules, proteins involved in host DNA replication, and host-derived antibodies. This chapter reviews the current structural information on AAV capsids and the capsid viral protein regions playing a role in the cellular interactions conferring an infective phenotype, which are then used to annotate the functional regions of the capsid. Based on the current data, the indication is that the AAVs, like other members of the Parvoviridae and other ssDNA viruses that form a T = 1 capsid, have evolved a multifunctional capsid with conserved core regions as is required for efficient capsid trafficking, capsid assembly, and genome packaging. Disparate surface loop structures confer differential receptor recognition and are involved in antibody recognition. The role of structural regions in capsid uncoating remains to be elucidated.
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Affiliation(s)
- Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, University of Florida, Gainesville, FL, USA.
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8
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Abstract
Adeno-associated virus (AAV) has emerged as an attractive vector for gene therapy. The benefits of using AAV for gene therapy include long-term gene expression, the inability to autonomously replicate without a helper virus, transduction of dividing and nondividing cells, and the lack of pathogenicity from wild-type infections. A number of Phase I and Phase II clinical trials utilizing AAV have been carried out worldwide (Aucoin et al., 2008; Mueller and Flotte, 2008). A number of challenges have been identified based upon data generated from these clinical trials. These challenges include (1) large scale manufacturing technologies in accordance with current Good Manufacturing Practices (cGMP), (2) tissue specific tropism of AAV vectors, (3) high-quality/high potency recombinant AAV vectors (rAAV), and (4) immune response to AAV capsids and transgene. In this chapter, we will provide an overview of AAV biology, AAV vectorology, rAAV manufacturing, and the current status on the latest rAAV clinical trials.
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Xie Q, Lerch TF, Meyer NL, Chapman MS. Structure-function analysis of receptor-binding in adeno-associated virus serotype 6 (AAV-6). Virology 2011; 420:10-9. [PMID: 21917284 PMCID: PMC3185213 DOI: 10.1016/j.virol.2011.08.011] [Citation(s) in RCA: 54] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2011] [Revised: 07/04/2011] [Accepted: 08/18/2011] [Indexed: 01/22/2023]
Abstract
Crystal structures of the AAV-6 capsid at 3Å reveal a subunit fold homologous to other parvoviruses with greatest differences in two external loops. The electrostatic potential suggests that receptor-attachment is mediated by four residues: Arg(576), Lys(493), Lys(459) and Lys(531), defining a positively charged region curving up from the valley between adjacent spikes. It overlaps only partially with the receptor-binding site of AAV-2, and the residues endowing the electrostatic character are not homologous. Mutational substitution of each residue decreases heparin affinity, particularly Lys(531) and Lys(459). Neither is conserved among heparin-binding serotypes, indicating that diverse modes of receptor attachment have been selected in different serotypes. Surface topology and charge are also distinct at the shoulder of the spike, where linear epitopes for AAV-2's neutralizing monoclonal antibody A20 come together. Evolutionarily, selection of changed side-chain charge may have offered a conservative means to evade immune neutralization while preserving other essential functionality.
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Affiliation(s)
- Qing Xie
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098
| | - Thomas F. Lerch
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098
| | - Nancy L. Meyer
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098
| | - Michael S. Chapman
- Department of Biochemistry & Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098
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Abstract
INTRODUCTION Glycogen storage disease (GSD) type Ia and Ib are disorders of impaired glucose homeostasis affecting the liver and kidney. GSD-Ib also affects neutrophils. Current dietary therapies cannot prevent long-term complications. In animal studies, recombinant adeno-associated virus (rAAV) vector-mediated gene therapy can correct or minimize multiple aspects of the disorders, offering hope for human gene therapy. AREAS COVERED A summary of recent progress in rAAV-mediated gene therapy for GSD-I; strategies to improve rAAV-mediated gene delivery, transduction efficiency and immune avoidance; and vector refinements that improve expression. EXPERT OPINION rAAV-mediated gene delivery to the liver can restore glucose homeostasis in preclinical models of GSD-I, but some long-term complications of the liver and kidney remain. Gene therapy for GSD-Ib is less advanced than for GSD-Ia and only transient correction of myeloid dysfunction has been achieved. A question remains as to whether a single rAAV vector can meet the expression efficiency and tropism required to treat all aspects of GSD-I, or if a multi-pronged approach is needed. An understanding of the strengths and weaknesses of rAAV vectors in the context of strategies to achieve efficient transduction of the liver, kidney and hematopoietic stem cells is required for treating GSD-I.
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Affiliation(s)
- Janice Y Chou
- Eunice Kennedy Shriver National Institute of Child Health and Human Development, National Institutes of Health, Section on Cellular Differentiation, Program on Developmental Endocrinology and Genetics, Bethesda, MD 20892 1830, USA.
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Mitchell AM, Nicolson SC, Warischalk JK, Samulski RJ. AAV's anatomy: roadmap for optimizing vectors for translational success. Curr Gene Ther 2010; 10:319-340. [PMID: 20712583 PMCID: PMC3920455 DOI: 10.2174/156652310793180706] [Citation(s) in RCA: 68] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2010] [Accepted: 07/20/2010] [Indexed: 12/14/2022]
Abstract
Adeno-Associated Virus based vectors (rAAV) are advantageous for human gene therapy due to low inflammatory responses, lack of toxicity, natural persistence, and ability to transencapsidate the genome allowing large variations in vector biology and tropism. Over sixty clinical trials have been conducted using rAAV serotype 2 for gene delivery with a number demonstrating success in immunoprivileged sites, including the retina and the CNS. Furthermore, an increasing number of trials have been initiated utilizing other serotypes of AAV to exploit vector tropism, trafficking, and expression efficiency. While these trials have demonstrated success in safety with emerging success in clinical outcomes, one benefit has been identification of issues associated with vector administration in humans (e.g. the role of pre-existing antibody responses, loss of transgene expression in non-immunoprivileged sites, and low transgene expression levels). For these reasons, several strategies are being used to optimize rAAV vectors, ranging from addition of exogenous agents for immune evasion to optimization of the transgene cassette for enhanced therapeutic output. By far, the vast majority of approaches have focused on genetic manipulation of the viral capsid. These methods include rational mutagenesis, engineering of targeting peptides, generation of chimeric particles, library and directed evolution approaches, as well as immune evasion modifications. Overall, these modifications have created a new repertoire of AAV vectors with improved targeting, transgene expression, and immune evasion. Continued work in these areas should synergize strategies to improve capsids and transgene cassettes that will eventually lead to optimized vectors ideally suited for translational success.
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Affiliation(s)
- Angela M. Mitchell
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Microbiology and Immunology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Sarah C. Nicolson
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - Jayme K. Warischalk
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - R. Jude Samulski
- UNC Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
- Department of Pharmacology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
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Lerch TF, Xie Q, Chapman MS. The structure of adeno-associated virus serotype 3B (AAV-3B): insights into receptor binding and immune evasion. Virology 2010; 403:26-36. [PMID: 20444480 DOI: 10.1016/j.virol.2010.03.027] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2010] [Revised: 03/03/2010] [Accepted: 03/17/2010] [Indexed: 12/19/2022]
Abstract
Adeno-associated viruses (AAVs) are leading candidate vectors for human gene therapy. AAV serotypes have broad cellular tropism and use a variety of cellular receptors. AAV serotype 3 binds to heparan sulfate proteoglycan prior to cell entry and is serologically distinct from other serotypes. The capsid features that distinguish AAV-3B from other serotypes are poorly understood. The structure of AAV-3B has been determined to 2.6A resolution from twinned crystals of an infectious virus. The most distinctive structural features are located in regions implicated in receptor and antibody binding, providing insights into the cell entry mechanisms and antigenic nature of AAVs. We show that AAV-3B has a lower affinity for heparin than AAV-2, which can be rationalized by the distinct features of the AAV-3B capsid. The structure of AAV-3B provides an additional foundation for the future engineering of improved gene therapy vectors with modified receptor binding or antigenic characteristics.
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Affiliation(s)
- Thomas F Lerch
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health & Science University, Portland, OR 97239-3098, USA
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13
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Asokan A. Reengineered AAV vectors: old dog, new tricks. DISCOVERY MEDICINE 2010; 9:399-403. [PMID: 20515607 PMCID: PMC2900186] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Adeno-associated viral (AAV) vectors have emerged in recent years as powerful tools for therapeutic gene transfer. Successes in clinical trials and the discovery of several hundreds of naturally occurring AAV isolates have triggered efforts to understand and manipulate this deceptively simple parvovirus for a myriad of gene therapy applications. Exciting breakthroughs based on directed evolution of novel tissue-specific variants from combinatorial AAV libraries have been reported. Recent approaches driven by the availability of structural information have yielded a new generation of reengineered AAV vectors.
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Affiliation(s)
- Aravind Asokan
- Gene Therapy Center, The University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
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14
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Mitchell M, Nam HJ, Carter A, McCall A, Rence C, Bennett A, Gurda B, McKenna R, Porter M, Sakai Y, Byrne BJ, Muzyczka N, Aslanidi G, Zolotukhin S, Agbandje-McKenna M. Production, purification and preliminary X-ray crystallographic studies of adeno-associated virus serotype 9. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:715-8. [PMID: 19574648 PMCID: PMC2705643 DOI: 10.1107/s1744309109021460] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2009] [Accepted: 06/05/2009] [Indexed: 11/10/2022]
Abstract
Adeno-associated virus (AAV) serotype 9, which is under development for gene-delivery applications, shows significantly enhanced capsid-associated transduction efficiency in muscle compared with other AAV serotypes. With the aim of characterizing the structural determinants of this property, the purification, crystallization and preliminary X-ray crystallographic analyses of the AAV9 viral capsid are reported. The crystals diffracted X-rays to 2.8 A resolution using synchrotron radiation and belonged to the trigonal space group P3(2), with unit-cell parameters a = b = 251.0, c = 640.0 A. There are three complete viral capsids in the crystal unit cell. The orientation and position of the asymmetric unit capsid have been determined by molecular-replacement methods and structure determination is in progress.
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Affiliation(s)
- Matthew Mitchell
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Hyun-Joo Nam
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Adam Carter
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Angela McCall
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Chelsea Rence
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Antonette Bennett
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Brittney Gurda
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Robert McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Mark Porter
- Department of Molecular Genetics and Microbiology and Powell Gene Therapy Center, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Yoshihisa Sakai
- Department of Molecular Genetics and Microbiology and Powell Gene Therapy Center, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Barry J. Byrne
- Department of Molecular Genetics and Microbiology and Powell Gene Therapy Center, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Nicholas Muzyczka
- Department of Molecular Genetics and Microbiology and Powell Gene Therapy Center, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - George Aslanidi
- Department of Pediatrics, Division of Cell and Molecular Therapy, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Sergei Zolotukhin
- Department of Pediatrics, Division of Cell and Molecular Therapy, College of Medicine, University of Florida, Gainesville, FL 32610, USA
| | - Mavis Agbandje-McKenna
- Department of Biochemistry and Molecular Biology, Center for Structural Biology, McKnight Brain Institute, College of Medicine, University of Florida, Gainesville, FL 32610, USA
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Lerch TF, Xie Q, Ongley HM, Hare J, Chapman MS. Twinned crystals of adeno-associated virus serotype 3b prove suitable for structural studies. Acta Crystallogr Sect F Struct Biol Cryst Commun 2009; 65:177-83. [PMID: 19194015 PMCID: PMC2635862 DOI: 10.1107/s1744309109000372] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/04/2008] [Accepted: 01/05/2009] [Indexed: 11/10/2022]
Abstract
Adeno-associated viruses (AAVs) are leading candidate vectors for gene-therapy applications. The AAV-3b capsid is closely related to the well characterized AAV-2 capsid (87% identity), but sequence and presumably structural differences lead to distinct cell-entry and immune-recognition properties. In an effort to understand these differences and to perhaps harness them, diffraction-quality crystals of purified infectious AAV-3b particles have been grown and several partial diffraction data sets have been recorded. The crystals displayed varying levels of merohedral twinning that in earlier times would have rendered them unsuitable for structure determination, but here is shown to be a tractable complication.
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Affiliation(s)
- Thomas F. Lerch
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health and Science University, Portland, OR 97239-3098, USA
| | - Qing Xie
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health and Science University, Portland, OR 97239-3098, USA
| | - Heather M. Ongley
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4381, USA
| | - Joan Hare
- Institute of Molecular Biophysics, Florida State University, Tallahassee, FL 32306-4381, USA
| | - Michael S. Chapman
- Department of Biochemistry and Molecular Biology, School of Medicine, Oregon Health and Science University, Portland, OR 97239-3098, USA
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