Residual DNA impurities in AAV vectors—nature and transcription

Recombinant adeno-associated viruses (rAAVs) produced by transfecting DNA plasmids into mammalian cells can inadvertently package host cell DNA (hcDNA) and plasmid DNA inside their capsids. Although the percentage of these DNA impurities is low compared to the rAAV genome in vector preparations, it...

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Main Authors: Hsin-I Jen, Patrick Wilkinson, Xiaohui Lu, Wei Zhang
Format: Article
Language:English
Published: Elsevier 2025-09-01
Series:Molecular Therapy: Methods & Clinical Development
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Online Access:http://www.sciencedirect.com/science/article/pii/S2329050125000981
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author Hsin-I Jen
Patrick Wilkinson
Xiaohui Lu
Wei Zhang
author_facet Hsin-I Jen
Patrick Wilkinson
Xiaohui Lu
Wei Zhang
author_sort Hsin-I Jen
collection DOAJ
description Recombinant adeno-associated viruses (rAAVs) produced by transfecting DNA plasmids into mammalian cells can inadvertently package host cell DNA (hcDNA) and plasmid DNA inside their capsids. Although the percentage of these DNA impurities is low compared to the rAAV genome in vector preparations, it is essential to characterize the DNA impurities in gene therapy products due to the theoretical risks associated with unwanted gene expression and potential immunogenicity and oncogenicity in treated patients. We performed long-read sequencing in rAAV vector, with a focus on analyzing residual, non-transgene DNA within the capsids. Although we detected host cell and residual plasmid DNA impurities, they were predominantly incomplete sequences without coding potential. This indicated that while DNA impurities may be present in rAAV preparations, host cell and residual plasmid genes were unlikely to be expressed. This was supported by RNA sequencing (RNA-seq) analyses that showed minimal plasmid RNA transcripts and host cell RNA transcripts in the livers of mice dosed with rAAV. Overall, the results from these studies enable data-based risk assessment of co-packaged DNA impurities and a better understanding of potential adverse effects associated with rAAV gene therapy.
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series Molecular Therapy: Methods & Clinical Development
spelling doaj-art-27a62717f5ba43549c9474df801d8a732025-08-20T02:36:00ZengElsevierMolecular Therapy: Methods & Clinical Development2329-05012025-09-0133310150310.1016/j.omtm.2025.101503Residual DNA impurities in AAV vectors—nature and transcriptionHsin-I Jen0Patrick Wilkinson1Xiaohui Lu2Wei Zhang3Global CMC Development, Ultragenyx Pharmaceutical Inc, Woburn, MA, USAGene Therapy Research, Ultragenyx Pharmaceutical Inc, Somerville, MA, USAGlobal CMC Development, Ultragenyx Pharmaceutical Inc, Woburn, MA, USAGlobal CMC Development, Ultragenyx Pharmaceutical Inc, Woburn, MA, USA; Corresponding author: Wei Zhang, Global CMC Development, Ultragenyx Pharmaceutical Inc, Woburn, MA, USA.Recombinant adeno-associated viruses (rAAVs) produced by transfecting DNA plasmids into mammalian cells can inadvertently package host cell DNA (hcDNA) and plasmid DNA inside their capsids. Although the percentage of these DNA impurities is low compared to the rAAV genome in vector preparations, it is essential to characterize the DNA impurities in gene therapy products due to the theoretical risks associated with unwanted gene expression and potential immunogenicity and oncogenicity in treated patients. We performed long-read sequencing in rAAV vector, with a focus on analyzing residual, non-transgene DNA within the capsids. Although we detected host cell and residual plasmid DNA impurities, they were predominantly incomplete sequences without coding potential. This indicated that while DNA impurities may be present in rAAV preparations, host cell and residual plasmid genes were unlikely to be expressed. This was supported by RNA sequencing (RNA-seq) analyses that showed minimal plasmid RNA transcripts and host cell RNA transcripts in the livers of mice dosed with rAAV. Overall, the results from these studies enable data-based risk assessment of co-packaged DNA impurities and a better understanding of potential adverse effects associated with rAAV gene therapy.http://www.sciencedirect.com/science/article/pii/S2329050125000981rAAVresidual DNAhost cell DNA transcriptionPacBio sequencinggene therapyDNA impurities
spellingShingle Hsin-I Jen
Patrick Wilkinson
Xiaohui Lu
Wei Zhang
Residual DNA impurities in AAV vectors—nature and transcription
Molecular Therapy: Methods & Clinical Development
rAAV
residual DNA
host cell DNA transcription
PacBio sequencing
gene therapy
DNA impurities
title Residual DNA impurities in AAV vectors—nature and transcription
title_full Residual DNA impurities in AAV vectors—nature and transcription
title_fullStr Residual DNA impurities in AAV vectors—nature and transcription
title_full_unstemmed Residual DNA impurities in AAV vectors—nature and transcription
title_short Residual DNA impurities in AAV vectors—nature and transcription
title_sort residual dna impurities in aav vectors nature and transcription
topic rAAV
residual DNA
host cell DNA transcription
PacBio sequencing
gene therapy
DNA impurities
url http://www.sciencedirect.com/science/article/pii/S2329050125000981
work_keys_str_mv AT hsinijen residualdnaimpuritiesinaavvectorsnatureandtranscription
AT patrickwilkinson residualdnaimpuritiesinaavvectorsnatureandtranscription
AT xiaohuilu residualdnaimpuritiesinaavvectorsnatureandtranscription
AT weizhang residualdnaimpuritiesinaavvectorsnatureandtranscription