Modified AAV2 Capsid Proteins for Retinal Transduction
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Solution Overview
Problem
Current adeno-associated viral (AAV) particles, particularly serotype 2, have limited efficiency in targeting and transducing retinal cells, which hampers gene delivery therapies for ocular tissues.
Innovation Solution
Development of variant AAV2 capsid proteins with specific amino acid substitutions and modifications in variable regions, such as DGE, DF, NA, and Y444F, to enhance tropism and transduction efficiency for retinal cells, including photoreceptors, retinal ganglion cells, and neural retinal cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If wild-type AAV2 capsid proteins are used, then the particle structure is stable and easy to manufacture, but the transduction efficiency in retinal cells is limited
Solution Approach 1:
The patent applies local quality by introducing specific amino acid substitutions at particular positions (e.g., Y444F, Q263A, K490T) within the capsid protein sequence while leaving the rest of the structure intact. This targeted modification approach improves retinal transduction efficiency without completely redesigning the entire capsid structure, thus balancing productivity improvement with manageable complexity
Solution Approach 2:
The patent employs parameter changes by systematically varying amino acid residues at specific positions in the capsid protein sequence. Through screening libraries with multiple substitutions (e.g., Y444F, Q263A, K490T, S492P), the invention identifies optimal parameter combinations that enhance retinal cell transduction while maintaining capsid stability and manufacturability
2Productivity
If AAV2 capsid library with multiple substitutions is screened, then transduction efficiency improves, but the screening process and validation become more complex
Solution Approach 1:
The patent applies segmentation by dividing the capsid protein into multiple variable regions (VRs) and introducing substitutions at specific positions within these regions. The screening process is segmented into systematic rounds, evaluating multiple substitutions independently and in combination. This modular approach to protein design and systematic screening reduces the overall complexity by breaking down the problem into manageable segments
Solution Approach 2:
The patent employs partial action by introducing a limited number of specific amino acid substitutions at predetermined positions rather than screening all possible combinations. The invention focuses on key variable regions and uses rational design to select substitutions that are most likely to improve retinal transduction, thereby reducing screening complexity while still achieving enhanced gene delivery rates
3Adaptability or versatility
If amino acid substitutions are introduced in variable regions, then tropism for retinal cells enhances, but the stability of the capsid structure may be compromised
Solution Approach 1:
The patent applies local quality by introducing amino acid substitutions specifically at positions within variable regions (e.g., Y444F in VR, Q263A in VRI) that are known to influence tissue tropism. These localized modifications enhance adaptability for retinal cell targeting while preserving the overall capsid structure stability, as the substitutions are confined to specific regions rather than throughout the entire protein
Solution Approach 2:
The patent employs beforehand cushioning by carefully selecting amino acid substitutions that are predicted to maintain structural stability while enhancing tropism. The screening process evaluates multiple candidate substitutions (e.g., Y444F, Q263A, K490T, S492P) and selects those that provide the desired adaptability improvement without compromising capsid integrity, thus cushioning against potential stability issues before they arise
Data Source
AI summary
Adeno associated viral (AAV) particles are emerging as a useful vehicle for gene delivery to various organs and tissues, one of them being the retina. Provided here are variant AAV (for example, variant serotype 2 (AAV2)) capsid proteins and variant capsid protein containing particles with enhanced ability to transduce retinal cells.