Related Experiment Video
Updated: May 10, 2026
08:14
Combined Genetic and Chemical Capsid Modifications of Adenovirus-Based Gene Transfer Vectors for Shielding and Targeting
Published on: October 26, 2018
CpG-depleted adeno-associated virus vectors evade immune detection
Susan M Faust1, Peter Bell, Benjamin J Cutler
1Gene Therapy Program, Department of Pathology and Laboratory Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA.
The Journal of Clinical Investigation
|June 20, 2013
Summary
To improve gene therapy for muscle diseases, researchers found that removing CpG sequences from adeno-associated virus (AAV) vectors reduced immune responses. This CpG-depleted AAV approach led to stable transgene expression and minimal immune cell infiltration in mice.
Area of Science:
- Immunology
- Gene Therapy
- Virology
Background:
- Adeno-associated virus (AAV) vectors are promising for skeletal muscle gene therapy but can trigger immune responses.
- Toll-like receptor 9 (TLR9) plays a role in these AAV-directed immune reactions.
- Current AAV vectors do not effectively bypass TLR9-mediated immunity.
Purpose of the Study:
- To investigate the role of TLR9 in immune responses to AAV vectors in mouse skeletal muscle.
- To determine if depleting CpG sequences from AAV vectors can circumvent TLR9-dependent immunity.
Main Methods:
- Comparison of immunological responses in wild-type (WT) and Tlr9-deficient mice after skeletal muscle gene transfer with an immunogenic AAV vector (AAVrh32.33).
- Assessment of T cell responses (IFN-γ), cellular infiltrate, and transgene expression.
- Evaluation of CpG-depleted AAVrh32.33 vectors for their ability to establish persistent transgene expression and evade immunity.
Main Results:
- Tlr9-deficient mice showed suppressed T cell responses to AAV capsid and transgene antigens.
- Immunity suppression in Tlr9-deficient mice resulted in minimal cellular infiltrate and stable transgene expression.
- CpG-depleted AAVrh32.33 vectors achieved persistent transgene expression, evaded immunity, and minimized effector cell infiltration.
Conclusions:
- TLR9 signaling is a significant driver of immune responses against AAV vectors in skeletal muscle.
- Depleting CpG sequences from AAV vectors is a viable strategy to circumvent TLR9-mediated immunity.
- CpG-depleted AAV vectors hold potential for improving gene therapy outcomes in skeletal muscle diseases.
