Adeno-Associated Virus-Induced Neurotoxicity is Prevented by CpG Depletion

Area of Science:

• Neuroscience
• Gene Therapy
• Immunology

Background:

• Adeno-associated viruses (AAVs) are widely used for gene delivery to the nervous system.
• AAV administration can cause dendritic loss and synaptic weakening, potentially mediated by Toll-like receptor 9 (TLR9) activation.
• TLR9 blockers are effective but have drawbacks, including immunosuppression and high cost.

Purpose of the Study:

• To identify strategies for preventing AAV-induced neural damage without compromising immunity.
• To investigate the efficacy of reducing CpG motifs within the AAV genome as a protective measure.
• To develop tools to aid researchers in creating CpG-depleted AAV vectors.

Main Methods:

• Partial depletion of CpG motifs from AAV genome regions (transgene and introns) using synonymous codon mutations.
• Assessment of AAV-induced dendritic loss and synaptic weakening in mouse somatosensory cortex.
• Evaluation of transgene expression in vivo.
• Development of the CpG-Assist Tool (CpG-AT) for quantifying and depleting CpG sequences.

Main Results:

• Partial CpG depletion from the AAV genome effectively prevented AAV-induced dendritic loss and synaptic weakening.
• CpG depletion did not impair transgene expression in vivo.
• The CpG-Assist Tool (CpG-AT) was developed to facilitate the generation of CpG-depleted AAV sequences.

Conclusions:

• CpG depletion is a practical and effective strategy to mitigate AAV-induced neural circuit disruption.
• This approach enhances the safety and efficacy of AAV-mediated gene delivery.
• The CpG-AT tool provides a valuable resource for researchers working with AAV vectors.