Compositions and methods for expressing otoferlin

A method of treating hearing loss in a human subject having a mutation in an OTOF gene associated with Deafness, Autosomal Recessive 9 (DFNB9), the method comprising:

• administering to inner hair cells in an inner ear of the subject a first adeno-associated virus (AAV) particle comprising a first polynucleotide and
• a second AAV particle comprising a second polynucleotide, wherein
• (i) the first polynucleotide comprises inverted terminal repeat sequences flanking an expression cassette containing, from 5′ to 3′:
• (a) a promoter,
• (b) a partial coding sequence that encodes an N-terminal portion of an Otoferlin polypeptide,
• (c) a splice donor site, and
• (d) a first region of homology containing a sequence that is homologous to a sequence in the second polynucleotide, and
• (ii) the second polynucleotide comprises inverted terminal repeat sequences flanking an expression cassette containing, from 5′ to 3′:
• (a) a second region of homology containing a sequence that is homologous to a sequence in the first polynucleotide,
• (b) a splice acceptor site,
• (c) a partial coding sequence that encodes a C-terminal portion of the Otoferlin polypeptide, and
• (d) a polyadenylation (pA) signal sequence,
• wherein the first region of homology and the second region of homology are between 50 and 500 nucleotides, wherein the Otoferlin polypeptide comprises the amino acid sequence of SEQ ID NO:
• 6, and wherein, when introduced into a human cell, the first polynucleotide and the second polynucleotide combine to form a polynucleotide that encodes a full-length Otoferlin polypeptide.