USH1B Minigene AAV Vectors for Overcoming Gene Packaging Limits
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Solution Overview
Problem
Conventional Adeno-associated Viral (AAV) vector-mediated gene delivery approaches have been limited by the large size of the USH1B gene, hindering effective therapy for Usher Syndrome caused by mutations in the MYO7A gene.
Innovation Solution
Development of recombinant AAV vectors encoding truncated USH1B minigenes, flanked by AAV inverted terminal repeats, and formulated with tissue-specific promoters and capsids for targeted delivery to ocular cells, such as photoreceptor cells, using methods like subretinal injection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If conventional AAV vector-mediated gene delivery is used, then the delivery system is simple and well-established, but the large size of the USH1B gene prevents effective delivery
Solution Approach 1:
The USH1B gene is divided into multiple exons, and a minigene construct is designed containing only the essential exons (e.g., exons 1-10 or selected critical exons) that can be delivered by AAV vectors. This segmentation allows the gene therapy to fit within the AAV packaging capacity while still producing a functional protein product.
Solution Approach 2:
Non-essential portions of the USH1B gene are extracted and removed from the minigene construct. Only the critical coding sequences necessary for therapeutic effect are retained, reducing the overall gene size to accommodate AAV vector constraints while preserving therapeutic functionality.
2Reliability
If the complete USH1B gene is delivered, then full protein function is achieved, but the gene size exceeds AAV vector capacity
Solution Approach 1:
Instead of delivering the complete USH1B gene, a partial version (minigene) containing only the essential exons is delivered. This partial action is sufficient to produce a functional protein that can rescue the phenotypic defects in Usher syndrome, achieving therapeutic efficacy without requiring the full gene sequence.
Solution Approach 2:
The minigene construct is optimized by modifying parameters such as promoter selection, exon composition, and regulatory elements to ensure efficient expression from the reduced gene sequence. These parameter changes allow the truncated gene to produce adequate protein function within the constraints of AAV vector capacity.
Data Source
AI summary
Aspects of the disclosure relate to compositions and methods useful for delivering minigenes to a subject. Accordingly, the disclosure is based, in part, on isolated nucleic acids and gene therapy vectors, such as viral (e.g., rAAV) vectors, comprising one or more gene fragments encoding a therapeutic gene product, such as a protein or peptide (e.g. a minigene). In some embodiments, the disclosure relates to gene therapy vectors encoding a USH1B protein (e.g. the gene product of USH1B, also referred to as MY07A) or a portion thereof. In some embodiments, compositions described by the disclosure are useful for treating diseases associated with mutations in the USH1B (MY07A) gene, for example Usher Syndrome.