Disclosed are compositions and methods for treating diseases of the
mammalian eye, and in particular, complications of the
retina associated with Usher syndrome 1B (USH1B). Further disclosed are compositions and methods for treating diseases of the mammalian
inner ear, and in particular, complications of ear hair cells associated with Usher syndrome 1B (USH1B). The disclosure provides improved AAV-based, dual vector systems that facilitate the expression of full-length proteins whose coding sequences exceed that of the
polynucleotide packaging capacity of an individual AAV vector. Described herein are modified
hybrid dual vector systems that shift the coding sequence for the MYO7A
tail domain from the front-half vector to the back-half vector by altering the
split point (e.g., from between exons 23 and 24, to between exons 21 and 22), in order to eliminate the production of truncated MYO7A
protein. Further described herein are improved, codon-modified
hybrid and overlap vector systems in which putative stop codons and residual sequences in non-coding sequences are removed.