1
|
Marwidi Y, Nguyen HOB, Santos D, Wangzor T, Bhardwaj S, Ernie G, Prawdzik G, Lew G, Shivak D, Trias M, Padilla J, Tran H, Meyer K, Surosky R, Ward AM. A robust and flexible baculovirus-insect cell system for AAV vector production with improved yield, capsid ratios and potency. Mol Ther Methods Clin Dev 2024; 32:101228. [PMID: 38524756 PMCID: PMC10959708 DOI: 10.1016/j.omtm.2024.101228] [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: 02/09/2024] [Accepted: 02/28/2024] [Indexed: 03/26/2024]
Abstract
Manufacturing of adeno-associated viruses (AAV) for gene and cell therapy applications has increased significantly and spurred development of improved mammalian and insect cell-based production systems. We developed a baculovirus-based insect cell production system-the SGMO Helper-with a novel gene architecture and greater flexibility to modulate the expression level and content of individual Rep and Cap proteins. In addition, we incorporated modifications to the AAV6 capsid sequence that improves yield, capsid integrity, and potency. Production of recombinant AAV 6 (rAAV6) using the SGMO Helper had improved yields compared to the Bac-RepCap helper from the Kotin lab. SGMO Helper-derived rAAV6 is resistant to a previously described proteolytic cleavage unique to baculovirus-insect cell production systems and has improved capsid ratios and potency, in vitro and in vivo, compared with rAAV6 produced using Bac-RepCap. Next-generation sequencing sequence analysis demonstrated that the SGMO Helper is stable over six serial passages and rAAV6 capsids contain comparable amounts of non-vector genome DNA as rAAV6 produced using Bac-RepCap. AAV production using the SGMO Helper is scalable using bioreactors and has improved yield, capsid ratio, and in vitro potency. Our studies demonstrate that the SGMO Helper is an improved platform for AAV manufacturing to enable delivery of cutting-edge gene and cell therapies.
Collapse
Affiliation(s)
- Yoko Marwidi
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | | | - David Santos
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Tenzin Wangzor
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Sumita Bhardwaj
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Gabriel Ernie
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Gregg Prawdzik
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Garrett Lew
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - David Shivak
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Michael Trias
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Jada Padilla
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Hung Tran
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Kathleen Meyer
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | - Richard Surosky
- Sangamo Therapeutics, 501 Canal Boulevard, Richmond, CA 94804, USA
| | | |
Collapse
|
2
|
Hetzler Z, Marinakos SM, Lott N, Mohammad N, Lass-Napiorkowska A, Kolbe J, Turrentine L, Fields D, Overton L, Marie H, Hucknall A, Rammo O, George H, Wei Q. Adeno-associated virus genome quantification with amplification-free CRISPR-Cas12a. Gene Ther 2024; 31:304-313. [PMID: 38528117 DOI: 10.1038/s41434-024-00449-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2023] [Revised: 03/05/2024] [Accepted: 03/15/2024] [Indexed: 03/27/2024]
Abstract
Efficient manufacturing of recombinant Adeno-Associated Viral (rAAV) vectors to meet rising clinical demand remains a major hurdle. One of the most significant challenges is the generation of large amounts of empty capsids without the therapeutic genome. There is no standardized analytical method to accurately quantify the viral genes, and subsequently the empty-to-full ratio, making the manufacturing challenges even more complex. We propose the use of CRISPR diagnostics (CRISPR-Dx) as a robust and rapid approach to determine AAV genome titers. We designed and developed the CRISPR-AAV Evaluation (CRAAVE) assay to maximize sensitivity, minimize time-to-result, and provide a potentially universal design for quantifying multiple transgene constructs encapsidated within different AAV serotypes. We also demonstrate an on-chip CRAAVE assay with lyophilized reagents to minimize end user assay input. The CRAAVE assay was able to detect AAV titers as low as 7e7 vg/mL with high precision (<3% error) in quantifying unknown AAV titers when compared with conventional quantitative PCR (qPCR) method. The assay only requires 30 min of assay time, shortening the analytical workflow drastically. Our results suggest CRISPR-Dx could be a promising tool for efficient rAAV genome titer quantification and has the potential to revolutionize biomanufacturing process analytical technology (PAT).
Collapse
Affiliation(s)
- Zach Hetzler
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | | | - Noah Lott
- Biomanufacturing, Training, and Education Center (BTEC), North Carolina State University, Raleigh, NC, 27606, USA
| | - Noor Mohammad
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | | | - Jenna Kolbe
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | - Lauren Turrentine
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | - Delaney Fields
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, 27606, USA
| | - Laurie Overton
- Biomanufacturing, Training, and Education Center (BTEC), North Carolina State University, Raleigh, NC, 27606, USA
| | | | | | | | | | - Qingshan Wei
- Department of Chemical and Biomolecular Engineering, North Carolina State University, Raleigh, NC, 27606, USA.
| |
Collapse
|
3
|
Klementieva NV, Lunev EA, Shmidt AA, Loseva EM, Savchenko IM, Svetlova EA, Galkin II, Polikarpova AV, Usachev EV, Vassilieva SG, Marina VI, Dzhenkova MA, Romanova AD, Agutin AV, Timakova AA, Reshetov DA, Egorova TV, Bardina MV. RNA Interference Effectors Selectively Silence the Pathogenic Variant GNAO1 c.607 G > A In Vitro. Nucleic Acid Ther 2024; 34:90-99. [PMID: 38215303 DOI: 10.1089/nat.2023.0043] [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] [Indexed: 01/14/2024] Open
Abstract
RNA interference (RNAi)-based therapeutics hold the potential for dominant genetic disorders, enabling sequence-specific inhibition of pathogenic gene products. We aimed to direct RNAi for the selective suppression of the heterozygous GNAO1 c.607 G > A variant causing GNAO1 encephalopathy. By screening short interfering RNA (siRNA), we showed that GNAO1 c.607G>A is a druggable target for RNAi. The si1488 candidate achieved at least twofold allelic discrimination and downregulated mutant protein to 35%. We created vectorized RNAi by incorporating the si1488 sequence into the short hairpin RNA (shRNA) in the adeno-associated virus (AAV) vector. The shRNA stem and loop were modified to improve the transcription, processing, and guide strand selection. All tested shRNA constructs demonstrated selectivity toward mutant GNAO1, while tweaking hairpin structure only marginally affected the silencing efficiency. The selectivity of shRNA-mediated silencing was confirmed in the context of AAV vector transduction. To conclude, RNAi effectors ranging from siRNA to AAV-RNAi achieve suppression of the pathogenic GNAO1 c.607G>A and discriminate alleles by the single-nucleotide substitution. For gene therapy development, it is crucial to demonstrate the benefit of these RNAi effectors in patient-specific neurons and animal models of the GNAO1 encephalopathy.
Collapse
Affiliation(s)
- Natalia V Klementieva
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
| | - Evgenii A Lunev
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anna A Shmidt
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | | | - Irina M Savchenko
- Marlin Biotech LLC, Sochi, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Ekaterina A Svetlova
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
| | - Ivan I Galkin
- Marlin Biotech LLC, Sochi, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| | - Anna V Polikarpova
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
| | - Evgeny V Usachev
- Laboratory of Translational Biomedicine, Gamaleya National Research Center for Epidemiology, Moscow, Russia
| | - Svetlana G Vassilieva
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
| | | | - Marina A Dzhenkova
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
| | - Anna D Romanova
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
| | - Anton V Agutin
- State Budgetary Healthcare Institution of Moscow Region "Balashikha Hospital," Balashikha, Russia
| | - Anna A Timakova
- Institute for Regenerative Medicine, Sechenov First Moscow State Medical University (Sechenov University), Moscow, Russia
| | | | - Tatiana V Egorova
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
| | - Maryana V Bardina
- Laboratory of Modeling and Gene Therapy of Hereditary Diseases, Institute of Gene Biology Russian Academy of Sciences, Moscow, Russia
- Marlin Biotech LLC, Sochi, Russia
- Center for Precision Genome Editing and Genetic Technologies for Biomedicine, Institute of Gene Biology, Russian Academy of Sciences, Moscow, Russia
| |
Collapse
|
4
|
Düchs MJ, Kratzer RF, Vieyra-Garcia P, Strobel B, Schönberger T, Groß P, Aljayyoussi G, Gupta A, Lang I, Klein H, Morilla SM, Hopf S, Park J, Kreuz S, Klugmann M, Igney FH. Riboswitch-controlled IL-12 gene therapy reduces hepatocellular cancer in mice. Front Immunol 2024; 15:1360063. [PMID: 38558809 PMCID: PMC10979303 DOI: 10.3389/fimmu.2024.1360063] [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: 12/22/2023] [Accepted: 02/14/2024] [Indexed: 04/04/2024] Open
Abstract
Hepatocellular carcinoma (HCC) and solid cancers with liver metastases are indications with high unmet medical need. Interleukin-12 (IL-12) is a proinflammatory cytokine with substantial anti-tumor properties, but its therapeutic potential has not been realized due to severe toxicity. Here, we show that orthotopic liver tumors in mice can be treated by targeting hepatocytes via systemic delivery of adeno-associated virus (AAV) vectors carrying the murine IL-12 gene. Controlled cytokine production was achieved in vivo by using the tetracycline-inducible K19 riboswitch. AAV-mediated expression of IL-12 led to STAT4 phosphorylation, interferon-γ (IFNγ) production, infiltration of T cells and, ultimately, tumor regression. By detailed analyses of efficacy and tolerability in healthy and tumor-bearing animals, we could define a safe and efficacious vector dose. As a potential clinical candidate, we characterized vectors carrying the human IL-12 (huIL-12) gene. In mice, bioactive human IL-12 was expressed in a vector dose-dependent manner and could be induced by tetracycline, suggesting tissue-specific AAV vectors with riboswitch-controlled expression of highly potent proinflammatory cytokines as an attractive approach for vector-based cancer immunotherapy.
Collapse
Affiliation(s)
- Matthias J. Düchs
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Ramona F. Kratzer
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Pablo Vieyra-Garcia
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co. KG, Vienna, Austria
| | - Benjamin Strobel
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Tanja Schönberger
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Peter Groß
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Ghaith Aljayyoussi
- Drug Discovery Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Aradhana Gupta
- Nonclinical Drug Safety, Boehringer Ingelheim Pharmaceuticals, Inc., Ridgefield, CT, United States
| | - Isabel Lang
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Holger Klein
- Global Computational Biology and Digital Sciences, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Sandra Martinez Morilla
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co. KG, Ridgefield, CT, United States
| | - Stefan Hopf
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim RCV GmbH & Co. KG, Vienna, Austria
| | - John Park
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Sebastian Kreuz
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Matthias Klugmann
- Research Beyond Borders, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| | - Frederik H. Igney
- Cancer Immunology and Immune Modulation, Boehringer Ingelheim Pharma GmbH & Co. KG, Biberach an der Riss, Germany
| |
Collapse
|
5
|
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.
Collapse
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
| |
Collapse
|
6
|
Chen Y, Hu S, Lee W, Walsh N, Iozza K, Huang N, Preston G, Drouin LM, Jia N, Deng J, Hebben M, Liao J. A Comprehensive Study of the Effects by Sequence Truncation within Inverted Terminal Repeats (ITRs) on the Productivity, Genome Packaging, and Potency of AAV Vectors. Microorganisms 2024; 12:310. [PMID: 38399714 PMCID: PMC10892565 DOI: 10.3390/microorganisms12020310] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/17/2023] [Revised: 01/23/2024] [Accepted: 01/26/2024] [Indexed: 02/25/2024] Open
Abstract
One of the primary challenges in working with adeno-associated virus (AAV) lies in the inherent instability of its inverted terminal repeats (ITRs), which play vital roles in AAV replication, encapsidation, and genome integration. ITRs contain a high GC content and palindromic structure, which occasionally results in truncations and mutations during plasmid amplification in bacterial cells. However, there is no thorough study on how these alterations in ITRs impact the ultimate AAV vector characteristics. To close this gap, we designed ITRs with common variations, including a single B, C, or D region deletion at one end, and dual deletions at both ends of the vector genome. These engineered ITR-carrying plasmids were utilized to generate AAV vectors in HEK293 cells. The crude and purified AAV samples were collected and analyzed for yield, capsid DNA-filled percentage, potency, and ITR integrity. The results show that a single deletion had minor impact on AAV productivity, packaging efficiency, and in vivo potency. However, deletions on both ends, except A, showed significant negative effects on the above characteristics. Our work revealed the role of ITR regions, A, B, C, and D for AAV production and DNA replication, and proposes a new strategy for the quality control of ITR-bearing plasmids and final AAV products.
Collapse
Affiliation(s)
| | | | | | | | | | | | | | | | | | | | | | - Jing Liao
- Genomic Medicine, Alexion, AstraZeneca Rare Disease, 65 Hayden Avenue, Lexington, MA 02421, USA; (Y.C.); (S.H.); (W.L.); (N.W.); (K.I.); (N.H.); (G.P.); (L.M.D.); (N.J.); (J.D.); (M.H.)
| |
Collapse
|
7
|
Maurer AC, Benyamini B, Fan VB, Whitney ON, Dailey GM, Darzacq X, Weitzman MD, Tjian R. Double-Strand Break Repair Pathways Differentially Affect Processing and Transduction by Dual AAV Vectors. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.09.19.558438. [PMID: 37790316 PMCID: PMC10542147 DOI: 10.1101/2023.09.19.558438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
Recombinant adeno-associated viral vectors (rAAV) are a powerful tool for gene delivery but have a limited DNA carrying capacity. Efforts to expand this genetic payload have focused on engineering the vector components, such as dual trans-splicing vectors which double the delivery size by exploiting the natural concatenation of rAAV genomes in host nuclei. We hypothesized that inefficient dual vector transduction could be improved by modulating host factors which affect concatenation. Since factors mediating concatenation are not well defined, we performed a genome-wide screen to identify host cell regulators. We discovered that Homologous Recombination (HR) is inhibitory to dual vector transduction. We demonstrate that depletion or inhibition of HR factors BRCA1 and Rad51 significantly increase reconstitution of a large split transgene by increasing both concatenation and expression from rAAVs. Our results define new roles for DNA damage repair in rAAV transduction and highlight the potential for pharmacological intervention to increase genetic payload of rAAV vectors.
Collapse
Affiliation(s)
- Anna C. Maurer
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- CIRM Center of Excellence, University of California, Berkeley, CA
| | - Brian Benyamini
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Vinson B. Fan
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Oscar N. Whitney
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
| | - Gina M. Dailey
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Li Ka Shing Center for Biomedical & Health Sciences, University of California, Berkeley, CA, USA
| | - Xavier Darzacq
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Li Ka Shing Center for Biomedical & Health Sciences, University of California, Berkeley, CA, USA
| | - Matthew D. Weitzman
- University of Pennsylvania Perelman School of Medicine and the Children’s Hospital of Philadelphia, Philadelphia, PA, USA
| | - Robert Tjian
- Department of Molecular and Cell Biology, University of California, Berkeley, CA, USA
- Li Ka Shing Center for Biomedical & Health Sciences, University of California, Berkeley, CA, USA
- Howard Hughes Medical Institute, University of California, Berkeley, CA, USA
| |
Collapse
|
8
|
Graves LE, Horton A, Alexander IE, Srinivasan S. Gene Therapy for Paediatric Homozygous Familial Hypercholesterolaemia. Heart Lung Circ 2023; 32:769-779. [PMID: 37012174 DOI: 10.1016/j.hlc.2023.01.017] [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: 07/14/2022] [Revised: 11/26/2022] [Accepted: 01/04/2023] [Indexed: 04/03/2023]
Abstract
The clinical outcome for children and adolescents with homozygous familial hypercholesterolaemia (HoFH) can be devastating, and treatment options are limited in the presence of a null variant. In HoFH, atherosclerotic risk accumulates from birth. Gene therapy is an appealing treatment option as restoration of low-density lipoprotein receptor (LDLR) gene function could provide a cure for HoFH. A clinical trial using a recombinant adeno-associated vector (rAAV) to deliver LDLR DNA to adult patients with HoFH was recently completed; results have not yet been reported. However, this treatment strategy may face challenges when translating to the paediatric population. The paediatric liver undergoes substantial growth which is significant as rAAV vector DNA persists primarily as episomes (extra-chromosomal DNA) and are not replicated during cell division. Therefore, rAAV-based gene addition treatment administered in childhood would likely only have a transient effect. With over 2,000 unique variants in LDLR, a goal of genomic editing-based therapy development would be to treat most (if not all) mutations with a single set of reagents. For a robust, durable effect, LDLR must be repaired in the genome of hepatocytes, which could be achieved using genomic editing technology such as clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 and a DNA repair strategy such as homology-independent targeted integration. This review discusses this issue in the context of the paediatric patient group with severe compound heterozygous or homozygous null variants which are associated with aggressive early-onset atherosclerosis and myocardial infarction, together with the important pre-clinical studies that use genomic editing strategies to treat HoFH in place of apheresis and liver transplantation.
Collapse
Affiliation(s)
- Lara E Graves
- Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Sydney, NSW, Australia; Children's Hospital at Westmead Clinical School, University of Sydney, Sydney, NSW, Australia; Gene Therapy Research Unit, Children's Medical Research Institute, Sydney, NSW, Australia.
| | - Ari Horton
- Monash Heart and Monash Children's Hospital, Monash Health, Melbourne, Vic, Australia; Monash Cardiovascular Research Centre, Victorian Heart Institute, Melbourne, Vic, Australia; Monash Genetics, Monash Health, Melbourne, Vic, Australia; Department of Genomic Medicine, The Royal Melbourne Hospital, Parkville, Vic, Australia; Department of Paediatrics, Monash University Clayton, Vic, Australia
| | - Ian E Alexander
- Children's Hospital at Westmead Clinical School, University of Sydney, Sydney, NSW, Australia; Gene Therapy Research Unit, Children's Medical Research Institute, Sydney, NSW, Australia
| | - Shubha Srinivasan
- Institute of Endocrinology and Diabetes, The Children's Hospital at Westmead, Sydney, NSW, Australia; Children's Hospital at Westmead Clinical School, University of Sydney, Sydney, NSW, Australia
| |
Collapse
|
9
|
Simpson BP, Yrigollen CM, Izda A, Davidson BL. Targeted long-read sequencing captures CRISPR editing and AAV integration outcomes in brain. Mol Ther 2023; 31:760-773. [PMID: 36617193 PMCID: PMC10014281 DOI: 10.1016/j.ymthe.2023.01.004] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Revised: 12/07/2022] [Accepted: 01/04/2023] [Indexed: 01/09/2023] Open
Abstract
Clustered regularly interspaced short palindromic repeats (CRISPR)/Cas9 gene editing is an emerging therapeutic modality that shows promise in Huntington's disease and spinocerebellar ataxia (SCA) mouse models. However, advancing CRISPR-based therapies requires methods to fully define in vivo editing outcomes. Here, we use polymerase-free, targeted long-read nanopore sequencing and evaluate single- and dual-gRNA AAV-CRISPR editing of human ATXN2 in transgenic mouse models of SCA type 2 (SCA2). Unbiased high sequencing coverage showed 10%-25% editing. Along with intended edits there was AAV integration, 1%-2% of which contained the entire AAV genome and were largely unmethylated. More than 150 kb deletions at target loci and rearrangements of the transgenic allele (1%) were also found. In contrast, PCR-based nanopore sequencing showed bias for partial AAV fragments and inverted terminal repeats (ITRs) and failed to detect full-length AAV. Cumulatively this work defines the spectrum of outcomes of CRISPR editing in mouse brain after AAV gene transfer using an unbiased long-read sequencing approach.
Collapse
Affiliation(s)
- Bryan P Simpson
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Cell and Molecular Biology Graduate Group, Biomedical Graduate Studies, University of Pennsylvania, Philadelphia, PA, USA
| | - Carolyn M Yrigollen
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Aleksandar Izda
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Beverly L Davidson
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA; Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA.
| |
Collapse
|
10
|
Merjane J, Chung R, Patani R, Lisowski L. Molecular mechanisms of amyotrophic lateral sclerosis as broad therapeutic targets for gene therapy applications utilizing adeno-associated viral vectors. Med Res Rev 2023. [PMID: 36786126 DOI: 10.1002/med.21937] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Revised: 08/19/2022] [Accepted: 02/02/2023] [Indexed: 02/15/2023]
Abstract
Despite the devastating clinical outcome of the neurodegenerative disease, amyotrophic lateral sclerosis (ALS), its etiology remains mysterious. Approximately 90% of ALS is characterized as sporadic, signifying that the patient has no family history of the disease. The development of an impactful disease modifying therapy across the ALS spectrum has remained out of grasp, largely due to the poorly understood mechanisms of disease onset and progression. Currently, ALS is invariably fatal and rapidly progressive. It is hypothesized that multiple factors can lead to the development of ALS, however, treatments are often focused on targeting specific familial forms of the disease (10% of total cases). There is a strong need to develop disease modifying treatments for ALS that can be effective across the full ALS spectrum of familial and sporadic cases. Although the onset of disease varies significantly between patients, there are general disease mechanisms and progressions that can be seen broadly across ALS patients. Therefore, this review explores the targeting of these widespread disease mechanisms as possible areas for therapeutic intervention to treat ALS broadly. In particular, this review will focus on targeting mechanisms of defective protein homeostasis and RNA processing, which are both increasingly recognized as design principles of ALS pathogenesis. Additionally, this review will explore the benefits of gene therapy as an approach to treating ALS, specifically focusing on the use of adeno-associated virus (AAV) as a vector for gene delivery to the CNS and recent advances in the field.
Collapse
Affiliation(s)
- Jessica Merjane
- Translational Vectorology Research Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead, New South Wales, Australia
| | - Roger Chung
- Department of Biomedical Sciences, Centre for Motor Neuron Disease Research, Faculty of Medicine & Health Sciences, Macquarie University, Sydney, New South Wales, Australia
| | - Rickie Patani
- Department of Neuromuscular Disease, UCL Queen Square Institute of Neurology, Queen Square, London, UK.,The Francis Crick Institute, London, UK
| | - Leszek Lisowski
- Translational Vectorology Research Unit, Children's Medical Research Institute, Faculty of Medicine and Health, The University of Sydney, Westmead, New South Wales, Australia.,Laboratory of Molecular Oncology and Innovative Therapies, Military Institute of Medicine, Warsaw, Poland
| |
Collapse
|
11
|
Shitik EM, Shalik IK, Yudkin DV. AAV- based vector improvements unrelated to capsid protein modification. Front Med (Lausanne) 2023; 10:1106085. [PMID: 36817775 PMCID: PMC9935841 DOI: 10.3389/fmed.2023.1106085] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2022] [Accepted: 01/16/2023] [Indexed: 02/05/2023] Open
Abstract
Recombinant adeno-associated virus (rAAV) is the leading platform for delivering genetic constructs in vivo. To date, three AAV-based gene therapeutic agents have been approved by the FDA and are used in clinical practice. Despite the distinct advantages of gene therapy development, it is clear that AAV vectors need to be improved. Enhancements in viral vectors are mainly associated with capsid protein modifications. However, there are other structures that significantly affect the AAV life cycle and transduction. The Rep proteins, in combination with inverted terminal repeats (ITRs), determine viral genome replication, encapsidation, etc. Moreover, transgene cassette expression in recombinant variants is directly related to AAV production and transduction efficiency. This review discusses the ways to improve AAV vectors by modifying ITRs, a transgene cassette, and the Rep proteins.
Collapse
|
12
|
Genome concentration, characterization, and integrity analysis of recombinant adeno-associated viral vectors using droplet digital PCR. PLoS One 2023; 18:e0280242. [PMID: 36696399 PMCID: PMC9876284 DOI: 10.1371/journal.pone.0280242] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Accepted: 12/24/2022] [Indexed: 01/26/2023] Open
Abstract
Precise, reproducible characterization of AAV is critical for comparing preclinical results between laboratories and determining a safe and effective clinical dose for gene therapy applications. In this study, we systematically evaluated numerous parameters to produce a simple and robust ddPCR protocol for AAV characterization. The protocol uses a low ionic strength buffer containing Pluronic-F68 and polyadenylic acid to dilute the AAV into the ddPCR concentration range and a 10-minute thermal capsid lysis prior to assembling ddPCR reactions containing MspI. A critical finding is that the buffer composition affected the ITR concentration of AAV but not the ITR concentration of a double stranded plasmid, which has implications when using a theoretical, stoichiometric conversion factor to obtain the titer based on the ITR concentration. Using this protocol, a more comprehensive analysis of an AAV vector formulation was demonstrated with multiple ddPCR assays distributed throughout the AAV vector genome. These assays amplify the ITR, regulatory elements, and eGFP transgene to provide a more confident estimate of the vector genome concentration and a high-resolution characterization of the vector genome identity. Additionally, we compared two methods of genome integrity analysis for three control sample types at eight different concentrations for each sample. The genome integrity was independent of sample concentration and the expected values were obtained when integrity was determined based on the excess number of positive droplets relative to the number of double positive droplets expected by chance co-encapsulation of two DNA targets. The genome integrity was highly variable and produced unexpected values when the double positive droplet percentage was used to calculate the genome integrity. A protocol using a one-minute thermal capsid lysis prior to assembling ddPCR reactions lacking a restriction enzyme used the non-ITR assays in a duplex ddPCR milepost experiment to determine the genome integrity using linkage analysis.
Collapse
|
13
|
DNA read count calibration for single-molecule, long-read sequencing. Sci Rep 2022; 12:17257. [PMID: 36319642 PMCID: PMC9626564 DOI: 10.1038/s41598-022-21606-5] [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: 06/21/2022] [Accepted: 09/29/2022] [Indexed: 11/17/2022] Open
Abstract
There are many applications in which quantitative information about DNA mixtures with different molecular lengths is important. Gene therapy vectors are much longer than can be sequenced individually via short-read NGS. However, vector preparations may contain smaller DNAs that behave differently during sequencing. We have used two library preparations each for Pacific Biosystems (PacBio) and Oxford Nanopore Technologies NGS to determine their suitability for quantitative assessment of varying sized DNAs. Equimolar length standards were generated from E. coli genomic DNA. Both PacBio library preparations provided a consistent length dependence though with a complex pattern. This method is sufficiently sensitive that differences in genomic copy number between DNA from E. coli grown in exponential and stationary phase conditions could be detected. The transposase-based Oxford Nanopore library preparation provided a predictable length dependence, but the random sequence starts caused the loss of original length information. The ligation-based approach retained length information but read frequency was more variable. Modeling of E. coli versus lambda read frequency via cubic spline smoothing showed that the shorter genome could be used as a suitable internal spike-in for DNAs in the 200 bp to 10 kb range, allowing meaningful QC to be carried out with AAV preparations.
Collapse
|
14
|
Ferrari S, Jacob A, Cesana D, Laugel M, Beretta S, Varesi A, Unali G, Conti A, Canarutto D, Albano L, Calabria A, Vavassori V, Cipriani C, Castiello MC, Esposito S, Brombin C, Cugnata F, Adjali O, Ayuso E, Merelli I, Villa A, Di Micco R, Kajaste-Rudnitski A, Montini E, Penaud-Budloo M, Naldini L. Choice of template delivery mitigates the genotoxic risk and adverse impact of editing in human hematopoietic stem cells. Cell Stem Cell 2022; 29:1428-1444.e9. [PMID: 36206730 PMCID: PMC9550218 DOI: 10.1016/j.stem.2022.09.001] [Citation(s) in RCA: 42] [Impact Index Per Article: 21.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2022] [Revised: 07/18/2022] [Accepted: 09/06/2022] [Indexed: 12/14/2022]
Abstract
Long-range gene editing by homology-directed repair (HDR) in hematopoietic stem/progenitor cells (HSPCs) often relies on viral transduction with recombinant adeno-associated viral vector (AAV) for template delivery. Here, we uncover unexpected load and prolonged persistence of AAV genomes and their fragments, which trigger sustained p53-mediated DNA damage response (DDR) upon recruiting the MRE11-RAD50-NBS1 (MRN) complex on the AAV inverted terminal repeats (ITRs). Accrual of viral DNA in cell-cycle-arrested HSPCs led to its frequent integration, predominantly in the form of transcriptionally competent ITRs, at nuclease on- and off-target sites. Optimized delivery of integrase-defective lentiviral vector (IDLV) induced lower DNA load and less persistent DDR, improving clonogenic capacity and editing efficiency in long-term repopulating HSPCs. Because insertions of viral DNA fragments are less frequent with IDLV, its choice for template delivery mitigates the adverse impact and genotoxic burden of HDR editing and should facilitate its clinical translation in HSPC gene therapy.
Collapse
Affiliation(s)
- Samuele Ferrari
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy,Vita-Salute San Raffaele University, Milan 20132, Italy
| | - Aurelien Jacob
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Daniela Cesana
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Marianne Laugel
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes 44200, France
| | - Stefano Beretta
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Angelica Varesi
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Giulia Unali
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Anastasia Conti
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Daniele Canarutto
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy,Vita-Salute San Raffaele University, Milan 20132, Italy,Pediatric Immunohematology Unit and BMT Program, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Luisa Albano
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Andrea Calabria
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Valentina Vavassori
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Carlo Cipriani
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Maria Carmina Castiello
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy,Institute for Genetic and Biomedical Research (UOS Milan Unit), National Research Council, Milan 20132, Italy
| | - Simona Esposito
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Chiara Brombin
- University Center for Statistics in the Biomedical Sciences, Vita-Salute San Raffaele University, Milan 20132, Italy
| | - Federica Cugnata
- University Center for Statistics in the Biomedical Sciences, Vita-Salute San Raffaele University, Milan 20132, Italy
| | - Oumeya Adjali
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes 44200, France
| | - Eduard Ayuso
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes 44200, France
| | - Ivan Merelli
- Institute for Biomedical Technologies, National Research Council, Segrate 20090, Italy
| | - Anna Villa
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy,Institute for Genetic and Biomedical Research (UOS Milan Unit), National Research Council, Milan 20132, Italy
| | - Raffaella Di Micco
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Anna Kajaste-Rudnitski
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | - Eugenio Montini
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy
| | | | - Luigi Naldini
- San Rafaelle Telethon Institute for Gene Therapy, IRCCS San Raffaele Scientific Institute, Milan 20132, Italy,Vita-Salute San Raffaele University, Milan 20132, Italy,Corresponding author
| |
Collapse
|
15
|
Mulcrone PL, Herzog RW, Xiao W. Adding recombinant AAVs to the cancer therapeutics mix. Mol Ther Oncolytics 2022; 27:73-88. [PMID: 36321134 PMCID: PMC9588955 DOI: 10.1016/j.omto.2022.09.009] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Gene therapy is a powerful biological tool that is reshaping therapeutic landscapes for several diseases. Researchers are using both non-viral and viral-based gene therapy methods with success in the lab and the clinic. In the cancer biology field, gene therapies are expanding treatment options and the possibility of favorable outcomes for patients. While cellular immunotherapies and oncolytic virotherapies have paved the way in cancer treatments based on genetic engineering, recombinant adeno-associated virus (rAAV), a viral-based module, is also emerging as a potential cancer therapeutic through its malleability, specificity, and broad application to common as well as rare tumor types, tumor microenvironments, and metastatic disease. A wide range of AAV serotypes, promoters, and transgenes have been successful at reducing tumor growth and burden in preclinical studies, suggesting more groundbreaking advances using rAAVs in cancer are on the horizon.
Collapse
Affiliation(s)
- Patrick L. Mulcrone
- Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202, USA,Department of Pediatrics, Indiana University, Indianapolis, IN 46202, USA
| | - Roland W. Herzog
- Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202, USA
| | - Weidong Xiao
- Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202, USA,Corresponding author Weidong Xiao, Herman B Wells Center for Pediatric Research, Indiana University, Indianapolis, IN 46202, USA.
| |
Collapse
|
16
|
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.
Collapse
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.
| |
Collapse
|
17
|
Tran NT, Lecomte E, Saleun S, Namkung S, Robin C, Weber K, Devine E, Blouin V, Adjali O, Ayuso E, Gao G, Penaud-Budloo M, Tai PW. Human and Insect Cell-Produced Recombinant Adeno-Associated Viruses Show Differences in Genome Heterogeneity. Hum Gene Ther 2022; 33:371-388. [PMID: 35293222 PMCID: PMC9063199 DOI: 10.1089/hum.2022.050] [Citation(s) in RCA: 32] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2022] [Accepted: 03/02/2022] [Indexed: 02/01/2023] Open
Abstract
In the past two decades, adeno-associated virus (AAV) vector manufacturing has made remarkable advancements to meet large-scale production demands for preclinical and clinical trials. In addition, AAV vectors have been extensively studied for their safety and efficacy. In particular, the presence of empty AAV capsids and particles containing "inaccurate" vector genomes in preparations has been a subject of concern. Several methods exist to separate empty capsids from full particles; but thus far, no single technique can produce vectors that are free of empty or partial (non-unit length) capsids. Unfortunately, the exact genome compositions of full, intermediate, and empty capsids remain largely unknown. In this work, we used AAV-genome population sequencing to explore the compositions of DNase-resistant, encapsidated vector genomes produced by two common production pipelines: plasmid transfection in human embryonic kidney cells (pTx/HEK293) and baculovirus expression vectors in Spodoptera frugiperda insect cells (rBV/Sf9). Intriguingly, our results show that vectors originating from the same construct design that were manufactured by the rBV/Sf9 system produced a higher degree of truncated and unresolved species than those generated by pTx/HEK293 production. We also demonstrate that empty particles purified by cesium chloride gradient ultracentrifugation are not truly empty but are instead packaged with genomes composed of a single truncated and/or unresolved inverted terminal repeat (ITR). Our data suggest that the frequency of these "mutated" ITRs correlates with the abundance of inaccurate genomes in all fractions. These surprising findings shed new light on vector efficacy, safety, and how clinical vectors should be quantified and evaluated.
Collapse
Affiliation(s)
- Ngoc Tam Tran
- Horae Gene Therapy Center, UMass Chan Medical School, Worcester, Massachusetts, USA
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Emilie Lecomte
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes, France
| | - Sylvie Saleun
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes, France
| | - Suk Namkung
- Horae Gene Therapy Center, UMass Chan Medical School, Worcester, Massachusetts, USA
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, USA
| | - Cécile Robin
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes, France
| | | | - Eric Devine
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes, France
| | - Veronique Blouin
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes, France
| | - Oumeya Adjali
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes, France
| | - Eduard Ayuso
- INSERM UMR 1089, University of Nantes, CHU of Nantes, Nantes, France
| | - Guangping Gao
- Horae Gene Therapy Center, UMass Chan Medical School, Worcester, Massachusetts, USA
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, USA
- Li Weibo Institute of Rare Diseases Research; UMass Chan Medical School, Worcester, Massachusetts, USA
| | | | - Phillip W.L. Tai
- Horae Gene Therapy Center, UMass Chan Medical School, Worcester, Massachusetts, USA
- Department of Microbiology and Physiological Systems, UMass Chan Medical School, Worcester, Massachusetts, USA
- Li Weibo Institute of Rare Diseases Research; UMass Chan Medical School, Worcester, Massachusetts, USA
| |
Collapse
|
18
|
Jeong D. Generation of Atrial-Specific Construct Using Sarcolipin Promoter-Associated CRM4 Enhancer. Methods Mol Biol 2022; 2573:115-132. [PMID: 36040590 DOI: 10.1007/978-1-0716-2707-5_9] [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: 01/14/2023]
Abstract
Cardiac gene therapy has been hampered by off-target expression of gene of interest irrespective of variety of delivery methods. To overcome this issue, cardiac-specific promoters provide target tissue specificity, although expression is often debilitated compared to that of ubiquitous promoters. We have previously shown that sarcolipin promoter with an enhancer calsequestrin cis-regulatory module 4 (CRM4) combination has an improved atrial specificity. Moreover, it showed a minimal extra-atrial expression, which is a significant advantage for AAV9-mediated cardiac gene therapy. Therefore, it can be a useful tool to study and treat atrial-specific diseases such as atrial fibrillation. In this chapter, we introduce practical and simple methodology for atrial-specific gene therapy using sarcolipin promoter with an enhancer CRM4.
Collapse
Affiliation(s)
- Dongtak Jeong
- Department of Molecular & Life Science, College of Science and Convergence Technology, Hanyang University ERICA, Ansan, South Korea.
| |
Collapse
|
19
|
PCR-Based Analytical Methods for Quantification and Quality Control of Recombinant Adeno-Associated Viral Vector Preparations. Pharmaceuticals (Basel) 2021; 15:ph15010023. [PMID: 35056080 PMCID: PMC8779925 DOI: 10.3390/ph15010023] [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: 12/06/2021] [Revised: 12/17/2021] [Accepted: 12/22/2021] [Indexed: 11/17/2022] Open
Abstract
Recombinant adeno-associated viral vectors (rAAV) represent a gene therapy tool of ever-increasing importance. Their utilization as a delivery vehicle for gene replacement, silencing and editing, among other purposes, demonstrate considerable versatility. Emerging vector utilization in various experimental, preclinical and clinical applications establishes the necessity of producing and characterizing a wide variety of rAAV preparations. Critically important characteristics concerning quality control are rAAV titer quantification and the detection of impurities. Differences in rAAV constructs necessitate the development of highly standardized quantification assays to make direct comparisons of different preparations in terms of assembly or purification efficiency, as well as experimental or therapeutic dosages. The development of universal methods for impurities quantification is rather complicated, since variable production platforms are utilized for rAAV assembly. However, general agreements also should be achieved to address this issue. The majority of methods for rAAV quantification and quality control are based on PCR techniques. Despite the progress made, increasing evidence concerning high variability in titration assays indicates poor standardization of the methods undertaken to date. This review summarizes successes in the field of rAAV quality control and emphasizes ongoing challenges in PCR applications for rAAV characterization. General considerations regarding possible solutions are also provided.
Collapse
|
20
|
Song L, Samulski RJ, Hirsch ML. Adeno-Associated Virus Vector Mobilization, Risk Versus Reality. Hum Gene Ther 2021; 31:1054-1067. [PMID: 32829671 DOI: 10.1089/hum.2020.118] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Recombinant adeno-associated viral (rAAV) vector mobilization is a largely theoretical process in which intact AAV vectors spread or "mobilize" from transduced cells and infect additional cells within, or external of, the initial host. This process can be helper virus-independent (vector alone) or helper virus-dependent (de novo rAAV production facilitated by superinfection of both wild-type AAV [wtAAV] and Adenovirus 5 [Ad] helper virus). Herein, rAAV production and mobilization with and without wtAAV were analyzed following plasmid transfection or viral transduction utilizing well-established in vitro conditions and analytical measurements. During in vitro production, wtAAV produced the highest titer with rAAV-luc (4.1 kb), rAAV-IDUA (3.7 kb), and rAAV-Nano-dysferlin (4.9 kb) generating 2.5-, 5.9-, or 10.7-fold lower amounts, respectively. Surprisingly, cotransfection of a wtAAV and an rAAV plasmid resulted in a uniform decrease in production of wtAAV in all instances with a concomitant increase of rAAV such that wtAAV:rAAV titers were at a ratio of 1:1 for all constructs investigated. These results were shown to be independent of the rAAV transgenic sequence, size, transgene, or promoter choice and point to novel aspects of wtAAV complementation that enhance current vector production systems yet to be defined. In a mobilization assay, a sizeable amount of rAAV recovered from infected 293 cell lysate remained intact and competent for a secondary round of infection (termed Ad-independent mobilization). In rAAV-infected cells coinfected with Ad and wtAAV, rAAV particle production was increased >50-fold compared with no Ad conditions. In addition, Ad-dependent rAAV vectors mobilized and resulted in >1,000-fold transduction upon a subsequent second-round infection, highlighting the reality of these theoretical safety concerns that can be manifested under various conditions. Overall, these studies document and signify the need for mobilization-resistant vectors and the opportunity to derive better vector production systems.
Collapse
Affiliation(s)
- Liujiang Song
- Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| | - R Jude Samulski
- 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
| | - Matthew L Hirsch
- Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA.,Department of Ophthalmology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, USA
| |
Collapse
|
21
|
von Jonquieres G, Rae CD, Housley GD. Emerging Concepts in Vector Development for Glial Gene Therapy: Implications for Leukodystrophies. Front Cell Neurosci 2021; 15:661857. [PMID: 34239416 PMCID: PMC8258421 DOI: 10.3389/fncel.2021.661857] [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: 01/31/2021] [Accepted: 05/12/2021] [Indexed: 12/12/2022] Open
Abstract
Central Nervous System (CNS) homeostasis and function rely on intercellular synchronization of metabolic pathways. Developmental and neurochemical imbalances arising from mutations are frequently associated with devastating and often intractable neurological dysfunction. In the absence of pharmacological treatment options, but with knowledge of the genetic cause underlying the pathophysiology, gene therapy holds promise for disease control. Consideration of leukodystrophies provide a case in point; we review cell type – specific expression pattern of the disease – causing genes and reflect on genetic and cellular treatment approaches including ex vivo hematopoietic stem cell gene therapies and in vivo approaches using adeno-associated virus (AAV) vectors. We link recent advances in vectorology to glial targeting directed towards gene therapies for specific leukodystrophies and related developmental or neurometabolic disorders affecting the CNS white matter and frame strategies for therapy development in future.
Collapse
Affiliation(s)
- Georg von Jonquieres
- Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
| | - Caroline D Rae
- Neuroscience Research Australia, Randwick, NSW, Australia
| | - Gary D Housley
- Translational Neuroscience Facility, Department of Physiology, School of Medical Sciences, UNSW Sydney, Sydney, NSW, Australia
| |
Collapse
|
22
|
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.
Collapse
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
| |
Collapse
|
23
|
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.
Collapse
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
| |
Collapse
|
24
|
Disruptors, a new class of oligonucleotide reagents, significantly improved PCR performance on templates containing stable intramolecular secondary structures. Anal Biochem 2021; 624:114169. [PMID: 33766577 DOI: 10.1016/j.ab.2021.114169] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2021] [Revised: 03/09/2021] [Accepted: 03/10/2021] [Indexed: 11/21/2022]
Abstract
Intramolecular secondary structures within templates have been shown to lower PCR performance. Whereas many approaches have been developed to mitigate such impairment on PCR, their effects can vary greatly depending on template sequences. Here we present a novel, universally effective approach to improve PCR performance involving specifically designed oligonucleotides called disruptors. A disruptor contained three functional components, an anchor designed to initiate template binding, an effector to disrupt intramolecular secondary structure, and a 3' blocker to prevent its elongation by DNA polymerase. A functional mechanism for a disruptor to improve PCR efficiency was proposed where anchor first binds to template followed by effector-mediated strand displacement to unwind intramolecular secondary structure. Such a mechanism was consistent with the observation that anchor played a more critical role for disruptor function. As an example of potential disruptor applications, inverted terminal repeat sequences of recombinant adeno-associated virus vectors were successfully amplified in the presence of disruptors despite their well-known reputation as some of the most difficult templates for PCR amplification and Sanger sequencing due to their ultra-stable T-shaped hairpin structures. In stark contrast, both DMSO and betaine, two PCR additives routinely used to facilitate PCR amplification and Sanger sequencing of GC-rich templates, did not demonstrate any improving effect.
Collapse
|
25
|
Rodríguez-Márquez E, Meumann N, Büning H. Adeno-associated virus (AAV) capsid engineering in liver-directed gene therapy. Expert Opin Biol Ther 2020; 21:749-766. [PMID: 33331201 DOI: 10.1080/14712598.2021.1865303] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Introduction: Gene therapy clinical trials with adeno-associated virus (AAV) vectors report impressive clinical efficacy data. Nevertheless, challenges have become apparent, such as the need for high vector doses and the induction of anti-AAV immune responses that cause the loss of vector-transduced hepatocytes. This fostered research focusing on development of next-generation AAV vectors capable of dealing with these hurdles.Areas Covered: While both the viral vector genome and the capsid are subjects to engineering, this review focuses on the latter. Specifically, we summarize the principles of capsid engineering strategies, and describe developments and applications of engineered capsid variants for liver-directed gene therapy.Expert Opinion: Capsid engineering is a promising strategy to significantly improve efficacy of the AAV vector system in clinical application. Reduction in vector dose will further improve vector safety, lower the risk of host immune responses and the cost of manufacturing. Capsid engineering is also expected to result in AAV vectors applicable to patients with preexisting immunity toward natural AAV serotypes.
Collapse
Affiliation(s)
- Esther Rodríguez-Márquez
- Universidad Autónoma De Madrid, Madrid, Spain.,Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany.,REBIRTH Research Center for Translational Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Nadja Meumann
- Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany.,REBIRTH Research Center for Translational Regenerative Medicine, Hannover Medical School, Hannover, Germany
| | - Hildegard Büning
- Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany.,REBIRTH Research Center for Translational Regenerative Medicine, Hannover Medical School, Hannover, Germany.,Center for Molecular Medicine Cologne, University of Cologne, Cologne, Germany.,German Center for Infection Research (DZIF, Partner Site Hannover-Braunschweig, Germany
| |
Collapse
|
26
|
Tran NT, Heiner C, Weber K, Weiand M, Wilmot D, Xie J, Wang D, Brown A, Manokaran S, Su Q, Zapp ML, Gao G, Tai PW. AAV-Genome Population Sequencing of Vectors Packaging CRISPR Components Reveals Design-Influenced Heterogeneity. Mol Ther Methods Clin Dev 2020; 18:639-651. [PMID: 32775498 PMCID: PMC7397707 DOI: 10.1016/j.omtm.2020.07.007] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Accepted: 07/06/2020] [Indexed: 02/07/2023]
Abstract
The gene therapy field has been galvanized by two technologies that have revolutionized treating genetic diseases: vectors based on adeno-associated viruses (AAVs), and clustered regularly interspaced short palindromic repeats (CRISPR)-Cas gene-editing tools. When combined into one platform, these safe and broadly tropic biotherapies can be engineered to target any region in the human genome to correct genetic flaws. Unfortunately, few investigations into the design compatibility of CRISPR components in AAV vectors exist. Using AAV-genome population sequencing (AAV-GPseq), we previously found that self-complementary AAV vector designs with strong DNA secondary structures can cause a high degree of truncation events, impacting production and vector efficacy. We hypothesized that the single-guide RNA (sgRNA) scaffold, which contains several loop regions, may also compromise vector integrity. We have therefore advanced the AAV-GPseq method to also interrogate single-strand AAV vectors to investigate whether vector genomes carrying Cas9-sgRNA cassettes can cause truncation events. We found that on their own, sgRNA sequences do not produce a high degree of truncation events. However, we demonstrate that vector genome designs that carry dual sgRNA expression cassettes in tail-to-tail configurations lead to truncations. In addition, we revealed that heterogeneity in inverted terminal repeat sequences in the form of regional deletions inherent to certain AAV vector plasmids can be interrogated.
Collapse
Affiliation(s)
- Ngoc Tam Tran
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Cheryl Heiner
- Pacific Biosciences, Inc., Menlo Park, CA 94025, USA
| | | | | | - Daniella Wilmot
- Program in Molecular Medicine and Center for AIDS Research, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Jun Xie
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, 01605, USA
- Viral Vector Core, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Dan Wang
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Alexander Brown
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Sangeetha Manokaran
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Viral Vector Core, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Qin Su
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Viral Vector Core, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Maria L. Zapp
- Program in Molecular Medicine and Center for AIDS Research, University of Massachusetts Medical School, Worcester, MA 01605, USA
| | - Guangping Gao
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, 01605, USA
- Viral Vector Core, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Li Weibo Institute for Rare Diseases Research, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| | - Phillip W.L. Tai
- Horae Gene Therapy Center, University of Massachusetts Medical School, Worcester, MA 01605, USA
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, 01605, USA
| |
Collapse
|