Bicistronic AAV Vectors for CNS HexA Subunit Co-Expression
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Solution Overview
Problem
Current treatments for Tay-Sachs and Sandhoff diseases, which result from hexosaminidase A deficiency, are inadequate, and delivering separate vectors for alpha and beta-subunits of hexosaminidase is inefficient due to low co-infection likelihood in the CNS, compromising efficacy.
Innovation Solution
Development of bicistronic AAV vectors encoding both hexosaminidase alpha and beta-subunits, configured for simultaneous expression in the CNS, using AAV inverted terminal repeats and bidirectional promoters to enhance therapeutic delivery.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate AAV vectors are used to deliver alpha and beta-subunits, then each subunit can be delivered independently, but the co-infection likelihood in the CNS is low, compromising therapeutic efficacy
Solution Approach 1:
The patent combines two separate AAV vectors into a single bicistronic vector that encodes both the alpha and beta-subunits of hexosaminidase A. This is achieved by placing both coding sequences under the control of a single promoter with internal ribosome entry sites (IRES) or 2A self-cleaving peptides, allowing simultaneous expression of both subunits from one vector, thereby ensuring co-infection and effective HexA enzyme reconstitution in the CNS.
2Reliability
If a single AAV vector encodes both subunits, then co-infection is guaranteed and therapeutic efficacy is improved, but the vector design complexity increases
Solution Approach 1:
The patent uses molecular intermediaries such as IRES (internal ribosome entry sites) or 2A self-cleaving peptide sequences as mediators between the promoter and the two coding sequences. These intermediaries allow the ribosome to independently translate both the alpha and beta-subunit coding sequences from a single polycistronic mRNA transcript, enabling dual protein expression without requiring separate promoters or vectors, thus managing complexity while maintaining efficacy.
3Ease of operation
If traditional treatment methods are used, then the approach is simple, but no effective treatment is available for GM2 gangliosidoses
Solution Approach 1:
The patent employs preliminary action by using AAV vectors that are pre-engineered with optimized promoter sequences, IRES elements, and coding sequences for both subunits. The vector is designed in advance to ensure efficient transduction of CNS cells and sustained expression of functional HexA enzyme, allowing a single administration to achieve long-term therapeutic effect without requiring complex repeated treatments or additional procedural steps.
Data Source
AI summary
Aspects of the disclosure relate to bicistronic AAV nucleic acid constructs comprising a transgene encoding hexosaminidase A (HEXA) and hexosaminidase (HEXB) proteins. In some embodiments, the disclosure provides methods for treating or preventing lysosomal storage disorders, such as Tay-Sachs disease and Sandhoff disease, using bicistronic nucleic acid constructs described by the disclosure.