Chemically Modified AAV Capsid Ligand Targeting
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Solution Overview
Problem
Current Adeno-Associated Virus (AAV) vector particles face limitations such as broad biodistribution, low therapeutic index, and poor efficacy due to pre-existing neutralizing antibodies, requiring high doses and leading to toxicity and manufacturing challenges, with existing methods for modifying the capsid being complex and not universally applicable.
Innovation Solution
Chemical coupling of ligands to the primary amino groups on the capsid proteins of AAV vector particles using a reagent with a thiourea bond, allowing for targeted tropism without genetic modification of the capsid sequence, enabling improved specificity and reduced therapeutic doses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If high doses of AAV vectors are administered to achieve therapeutic efficacy, then transduction efficiency is improved, but toxicity increases and manufacturing challenges arise
Solution Approach 1:
The patent applies local quality by modifying the capsid surface with specific ligands that provide targeted binding affinity to particular cell types. This localized functional enhancement allows the vector to selectively bind to target cells with high affinity, improving transduction efficiency at lower doses without the need for high-dose administration that would cause toxicity.
Solution Approach 2:
The patent changes the chemical parameters of the capsid by introducing chemically modified amino acid residues with specific functional groups. These parameter changes enable covalent attachment of targeting ligands, which fundamentally alters the vector's interaction properties with target cells, allowing efficient transduction at reduced doses.
2Adaptability or versatility
If AAV vectors are used for broad tissue transduction, then versatility is improved, but specificity to target tissues deteriorates
Solution Approach 1:
The patent implements local quality by attaching specific ligands to the capsid surface that provide localized recognition functions for particular cell types. This allows the vector to maintain its basic AAV transduction capabilities while adding specific targeting functions through the attached ligands, achieving both versatility and specificity.
Solution Approach 2:
The patent applies universality by creating a platform where the AAV capsid serves as a universal delivery vehicle that can be functionalized with different ligands for different target tissues. The chemically modified capsid provides a universal attachment point for various ligands, enabling the same vector platform to target multiple different tissue types with high specificity.
3Measurement precision
If chemical modification methods are used to enhance capsid targeting, then specificity is improved, but device complexity increases
Solution Approach 1:
The patent applies preliminary action by pre-installing chemically reactive amino acid residues (such as non-natural amino acids with specific functional groups) into the capsid sequence during vector construction. This preliminary modification creates ready-to-use attachment sites that simplify the subsequent ligand conjugation process, reducing overall complexity compared to de novo chemical modification methods.
Solution Approach 2:
The patent uses chemically modified amino acid residues as intermediaries between the capsid protein and the targeting ligands. These modified residues serve as molecular mediators that facilitate the attachment of diverse ligands through their specific functional groups, simplifying the conjugation chemistry and reducing process complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Enhances the therapeutic index by increasing specificity to target tissues, reducing off-target transduction, and overcoming neutralizing antibodies, thereby improving the efficacy and safety of AAV-mediated gene delivery.
Implementation Method 1
Chemical coupling of ligands to the primary amino groups on the capsid proteins of AAV vector particles using a reagent with a thiourea bond
Data Source
Figure 1A~1E
Figure 1F~1G
Figure 2A~2C
AI summary
The invention is directed to the field of gene therapy, i.e. gene delivery into target cells, tissue, organ and organism, and more particularly to gene delivery via viral vectors. The inventors showed that it is possible by chemical coupling to modulate the coupling of a ligand in the surface of the capsid of AAV, for example AAV2 and AAV3b. In particular, the present invention relates to a recombinant Adeno-Associated Virus (rAAV) vector particle having at least one primary amino group contained in the capsid proteins, chemically coupled with at least one ligand L, wherein coupling of said ligand L is implemented through a bond comprising a -CSNH- bond and an optionally substituted aromatic moiety. Particularly, the inventors tested the chemical coupling of mannose ligand on AAV2 for subretinally injection to rats. The present invention further relates to a method for chemically coupling an Adeno-Associated Virus (AAV) vector particle with at least one ligand L and to a Recombinant Adeno-Associated Virus (rAAV) vector particle obtained by said method as well as a pharmaceutical composition comprising it and their corresponding medical use.