Dual AAV-mediated gene therapy restores hearing in a DFNB9 mouse model

Area of Science:

• Genetics
• Otolaryngology
• Molecular Biology

Background:

• Profound congenital deafness often results from autosomal recessive genetic forms (DFNB).
• Adeno-associated virus (AAV)-based gene therapy offers therapeutic potential but faces limitations in vector packaging capacity and therapeutic window.
• DFNB9, a frequent genetic cause of congenital deafness, is linked to mutations in the otoferlin gene.

Purpose of the Study:

• To develop a gene therapy strategy for DFNB9 using a dual AAV approach to overcome packaging limitations.
• To evaluate the efficacy of this dual AAV strategy in restoring otoferlin expression and reversing deafness in a mouse model.

Main Methods:

• A dual AAV vector system was designed, with each vector carrying a portion of the otoferlin cDNA exceeding AAV packaging capacity.
• The vector pair was delivered to the mature cochlea of otoferlin-deficient (Otof-/-) mutant mice.
• Recombination of the delivered cDNAs and restoration of otoferlin expression were assessed.

Main Results:

• A single administration of the dual AAV vector pair resulted in the reconstitution of the full otoferlin cDNA coding sequence via recombination.
• Durable restoration of otoferlin expression was observed in transduced cells within the cochlea.
• The gene therapy led to a significant reversal of the deafness phenotype in the treated mice.

Conclusions:

• The dual AAV approach effectively bypasses vector packaging limitations for delivering large genes like otoferlin.
• This strategy demonstrates a promising therapeutic avenue for DFNB9 and potentially other genetic forms of deafness.
• The findings support the advancement of AAV-based gene therapy trials for congenital deafness patients.