A Self-Complementary AAV Proviral Plasmid System to Reduce Aberrant Cross-Packaging and ITR Promoter Activity in AAV Vector Preparations (Long-read)
Ontology highlight
ABSTRACT: A Self-Complementary AAV Proviral Plasmid System to Reduce Aberrant Cross-Packaging and ITR Promoter Activity in AAV Vector Preparations (Long-read)
Project description:Adeno-associated viral vectors (AAV) are a leading delivery system for gene therapy in animal models and humans. With several FDA-approved AAV gene therapies on the market, issues related to vector manufacturing have become increasingly important. In this study, we focused on potentially toxic DNA contaminants that can arise from AAV proviral plasmids, the raw materials required for manufacturing recombinant AAV in eukaryotic cells. Typical AAV proviral plasmids are circular DNAs containing a therapeutic gene cassette flanked by natural AAV inverted terminal repeat (ITR) sequences, and a plasmid backbone carrying prokaryotic sequences required for plasmid replication and selection in bacteria. While the majority of AAV particles package the intended therapeutic payload, some capsids instead package the bacterial sequences located on the proviral plasmid backbone. Since ITR sequences also have promoter activity, potentially toxic bacterial open reading frames can be produced in vivo, thereby representing a safety risk. In this study, we describe a new AAV proviral plasmid for vector manufacturing that (1) significantly decreases cross-packaged bacterial sequences; (2) increases correctly packaged AAV payloads; and (3) blunts ITR-driven transcription of cross-packaged material to avoid expressing potentially toxic bacterial sequences. This system may help improve the safety of AAV vector products.
Project description:Adeno-associated viral vectors (AAV) are a leading delivery system for gene therapy in animal models and humans. With several FDA-approved AAV gene therapies on the market, issues related to vector manufacturing have become increasingly important. In this study, we focused on potentially toxic DNA contaminants that can arise from AAV proviral plasmids, the raw materials required for manufacturing recombinant AAV in eukaryotic cells. Typical AAV proviral plasmids are circular DNAs containing a therapeutic gene cassette flanked by natural AAV inverted terminal repeat (ITR) sequences, and a plasmid backbone carrying prokaryotic sequences required for plasmid replication and selection in bacteria. While the majority of AAV particles package the intended therapeutic payload, some capsids instead package the bacterial sequences located on the proviral plasmid backbone. Since ITR sequences also have promoter activity, potentially toxic bacterial open reading frames can be produced in vivo, thereby representing a safety risk. In this study, we describe a new AAV proviral plasmid for vector manufacturing that (1) significantly decreases cross-packaged bacterial sequences; (2) increases correctly packaged AAV payloads; and (3) blunts ITR-driven transcription of cross-packaged material to avoid expressing potentially toxic bacterial sequences. This system may help improve the safety of AAV vector products.
Project description:A Self-Complementary AAV Proviral Plasmid System to Reduce Aberrant Cross-Packaging and ITR Promoter Activity in AAV Vector Preparations (Short-read)
Project description:Adeno-associated viral vectors (AAVs) are a leading delivery system for gene therapy in animal models and humans. With several Food and Drug Administration-approved AAV gene therapies on the market, issues related to vector manufacturing have become increasingly important. In this study, we focused on potentially toxic DNA contaminants that can arise from AAV proviral plasmids, the raw materials required for manufacturing recombinant AAV in eukaryotic cells. Typical AAV proviral plasmids are circular DNAs containing a therapeutic gene cassette flanked by natural AAV inverted terminal repeat (ITR) sequences, and a plasmid backbone carrying prokaryotic sequences required for plasmid replication and selection in bacteria. While the majority of AAV particles package the intended therapeutic payload, some capsids instead package the bacterial sequences located on the proviral plasmid backbone. Since ITR sequences also have promoter activity, potentially toxic bacterial open reading frames can be produced in vivo, thereby representing a safety risk. In this study, we describe a new AAV proviral plasmid for vector manufacturing that (1) significantly decreases cross-packaged bacterial sequences, (2) increases correctly packaged AAV payloads, and (3) blunts ITR-driven transcription of cross-packaged material to avoid expressing potentially toxic bacterial sequences. This system may help improve the safety of AAV vector products.
Project description:AAV-genome population sequencing detects the repair of mutated ITR structures and the impact of guide RNA cassette designs on vector genome integrity
Project description:This is an ATAC sequencing experiment to explore chromatin accessibility change in mouse skeletal muscle treated with either AAV-GFP or AAV-CAAHR (a constitutively active mutant aryl hydrocarbon receptor). Mice received intramuscular injection of the AAV 5 months before the harvest of muscle.
Project description:CRISPR-Cas9 delivery by AAV holds promise for gene therapy but faces critical barriers due to its potential immunogenicity and limited payload capacity. Here, we demonstrate genome engineering in postnatal mice using AAV-split-Cas9, a multi-functional platform customizable for genome-editing, transcriptional regulation, and other previously impracticable AAV-CRISPR-Cas9 applications. We identify crucial parameters that impact efficacy and clinical translation of our platform, including viral biodistribution, editing efficiencies in various organs, antigenicity, immunological reactions, and physiological outcomes. These results reveal that AAV-CRISPR-Cas9 evokes host responses with distinct cellular and molecular signatures, but unlike alternative delivery methods, does not induce detectable cellular damage in vivo. Our study provides a foundation for developing effective genome therapeutics mRNA-Seq from muscles (9 samples; 3 mice x 3 conditions) and lymph nodes (9 samples; 3 mice x 3 conditions).
Project description:AAV gene therapy has recently been approved for clinical use and shown to be efficacious and safe in a growing number of clinical trials. However, the safety of AAV as a gene therapy has been challenged by a few studies that documented hepatocellular carcinoma (HCC) after AAV gene delivery in mice. The association between AAV and HCC has been difficult to reconcile and is the subject of intense debate because numerous AAV studies have not reported toxicity. Here, we report a comprehensive study of HCC in a large number of mice following therapeutic AAV gene delivery. Using a sensitive high-throughput integration site-capture technique and global expressional analysis, we found that AAV integration into the Rian locus and the over-expression of a proximal gene, Rtl1, were associated with HCC. In addition, we identify a number of genes with differential expression that maybe useful in the study, diagnosis and treatment of HCC. We demonstrate that AAV vector dose, enhancer-promoter selection, and the timing of gene delivery are the defining factors in AAV-mediated insertional mutagenesis. Our results help explain the AAV-mediated genotoxicity previously observed and have important implications for the design of both safer AAV vectors and gene therapy studies. To investigate the possibility that insertional mutagenesis by AAV contributed to the development of HCC, we collected normal and tumor tissues from adult mouse livers that received AAV injection at a neonatal stage.