AAV Capsid Engineering for GPR108-Dependent Transduction
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Solution Overview
Problem
Current methodologies are insufficient in identifying major adeno-associated virus (AAV) entry factors and characterizing subfamily-wide receptor and entry factor requirements, leading to a disconnect in understanding how these factors influence transduction efficiency.
Innovation Solution
Genetically modifying AAV capsids with heterologous VP1 polypeptide sequences that either require or do not require the presence of the GPR108 receptor for transduction, allowing for modulation of transduction efficiency by engineering AAVs to be GPR108-dependent or independent, and using compounds to increase or decrease GPR108 expression in cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If cDNA overexpression is used to identify factors that increase transduction, then attachment at the cell surface increases, but the mechanism by which these factors influence transduction remains poorly characterized
Solution Approach 1:
The patent segments the AAV capsid into individual VP1 polypeptide sequences from different serotypes and systematically tests each one's ability to confer GPR108 dependency. This segmentation allows precise identification of which capsid sequences are responsible for specific transduction mechanisms, resolving the mechanistic information loss from previous bulk overexpression studies.
Solution Approach 2:
The patent creates a universal platform by testing VP1 sequences from multiple AAV serotypes (AAV1, AAV2, AAV3, AAV4, AAV6.2, AAV7, AAV8, AAV9, and others) to determine their GPR108 dependency. This multi-functional approach reveals that GPR108 is a subfamily-wide entry factor, providing universal mechanistic insight across AAV serotypes rather than serotype-specific information.
2Reliability
If knock-down and knock-out studies are performed on identified factors, then transduction defects are reduced, but these factors cannot be defined as required entry receptors
Solution Approach 1:
The patent uses GPR108 as an intermediary to definitively establish receptor requirements. By creating AAV vectors that are GPR108-dependent and testing them in GPR108 knockout cells, the study provides clear evidence that GPR108 is a required entry receptor, resolving the ambiguity from previous knock-down studies where transduction defects were not observed.
Solution Approach 2:
Instead of knocking down candidate factors and observing whether transduction fails (which showed no major defects), the patent inverts the approach by engineering AAVs to be dependent on GPR108 and then testing whether they can transduce GPR108 knockout cells. This inversion provides definitive proof of GPR108 as a required receptor, as the engineered GPR108-dependent AAVs fail to transduce knockout cells.
3Productivity
If AAV capsids are genetically modified with heterologous VP1 polypeptide sequences, then transduction efficiency is modulated, but the complexity of capsid engineering increases
Solution Approach 1:
The patent changes the key parameter of VP1 polypeptide sequence in the AAV capsid to modulate transduction efficiency. By substituting VP1 sequences from different serotypes, the study achieves controlled modulation of GPR108 dependency and transduction efficiency without requiring complex multi-component engineering, as the capsid can be engineered with a single heterologous VP1 sequence.
Data Source
AI summary
Methods and compositions for modulating the transduction efficiency of an adeno-associated vims (AAV) into a cell or tissue are provided.