Synthetic AAV Capsid Library via Surface Residue Gene Synthesis
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for generating AAV capsid libraries suffer from sequence bias and limited diversity, with existing approaches either introducing mutations randomly or recombining blocks of DNA, leading to inefficient targeting of specific tissues and organs due to promiscuity and susceptibility to neutralization by human antibodies.
Innovation Solution
A gene synthesis-based approach that alters only the amino acid residues exposed on the capsid surface, allowing for virtual recombination of naturally-occurring sequences to create combinatorial libraries that enhance compatibility with the capsid structure and function, thereby improving targeting specificity and efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If random mutation or block recombination methods are used to generate AAV capsid libraries, then sequence diversity is introduced, but sequence bias occurs and capsid structure compatibility is reduced
Solution Approach 1:
The patent applies local quality by restricting mutations to only the surface-exposed amino acid residues of the capsid protein, while keeping the internal and structurally critical residues unchanged. This localized approach allows sequence diversity to be introduced in regions that are tolerable to variation (surface loops) without compromising the overall capsid structure and function.
Solution Approach 2:
The patent segments the capsid protein sequence into surface-exposed regions and internal regions, treating them differently. Only the surface-exposed segments are subjected to mutation and recombination, while internal segments are preserved. This segmentation allows diverse library generation while maintaining structural integrity.
2Adaptability or versatility
If wild-type AAV capsids are used, then broad tissue tropism is achieved, but targeting specificity to particular organs is insufficient
Solution Approach 1:
The patent changes the amino acid sequence parameters of the capsid protein at surface-exposed positions to alter the physical-chemical properties of the capsid surface. These parameter changes in specific residues modify the interaction between the capsid and tissue-specific receptors, enabling enhanced targeting specificity to particular organs such as liver, brain, or muscle while maintaining reasonable broad tropism.
3Productivity
If high viral particle doses are administered to achieve effective transduction, then transduction efficiency is improved, but immunogenicity and neutralization risk increase
Solution Approach 1:
The patent modifies only the local surface properties of the capsid through targeted amino acid substitutions, rather than making global changes to the entire capsid structure. This localized modification approach achieves enhanced tissue specificity and reduced immunogenicity by altering only the interaction interfaces with the immune system and target cells, while preserving the essential capsid functions.
Data Source
AI summary
Disclosed are compositions and methods for producing modified adeno-associated virus (AAV) cap genes and combinatorial libraries of chimeric AAV vectors and virions; selecting for virions displaying cell-specific tropisms; and, in certain embodiments, producing helper vectors containing one or more modified AAV cap genes. The synthetic combinatorial AAV capsid libraries of the invention are useful in introducing into selected target host cells one or more nucleic acid molecules. The viral vectors and genetic constructs disclosed herein are also useful in a variety of diagnostic and/or therapeutic gene-therapy regimens.