Modified AAV Capsid Proteins for Microglia Targeting
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Solution Overview
Problem
Current methods are inadequate for efficiently targeting microglia in the central nervous system (CNS) for therapeutic interventions, as existing AAV vectors like PHP.eB fail to infect microglia in vivo, limiting the ability to deliver gene editing or therapeutic cargo to these cells effectively.
Innovation Solution
Development of novel AAV capsid proteins with modified amino acid sequences that enable efficient crossing of the blood-brain barrier and specific targeting of microglia and brain macrophages, including CNS-infiltrating macrophages derived from recruited monocytes, by incorporating specific insertion sequences into the AAV capsid binding arm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If PHP.eB AAV vectors are used to target CNS cells, then transduction efficiency in neurons is improved, but infection of microglia is insufficient
Solution Approach 1:
The patent applies local quality by modifying specific regions of the AAV capsid protein (amino acids 588-596 in VP1, 588-596 in VP3, or 586-594 in VP2) to enable microglia targeting while preserving overall capsid function. The localized amino acid substitution in the binding arm region specifically enhances microglia interaction without compromising neuronal transduction capabilities.
Solution Approach 2:
The patent changes the chemical parameters of the capsid protein by substituting specific amino acids at defined positions. This parameter change transforms the capsid's binding properties, enabling it to recognize and enter microglia while maintaining its ability to cross the blood-brain barrier and infect other CNS cells.
2Measurement precision
If AAV vectors are modified to target specific cell types, then cell-type specificity is improved, but transduction efficiency may be reduced
Solution Approach 1:
The invention applies local quality by making targeted amino acid substitutions only in the capsid binding arm region (amino acids 586-596), leaving the rest of the capsid structure intact. This localized modification achieves microglia specificity while preserving the overall transduction efficiency of the AAV vector.
Solution Approach 2:
The modified capsid proteins maintain multi-functionality by simultaneously enabling blood-brain barrier crossing, neuronal transduction, and microglia infection. The capsid retains broad CNS cell targeting capability while adding specific microglia recognition, making the vector universally effective across multiple CNS cell types.
3Measurement precision
If amino acid substitutions are made in the capsid binding arm, then microglia targeting is improved, but capsid stability may be affected
Solution Approach 1:
The patent applies local quality by restricting amino acid substitutions to the binding arm region (amino acids 586-596), which is a surface-exposed loop region. This localized modification affects binding specificity while minimizing disruption to the core capsid structure and maintaining overall structural stability.
Solution Approach 2:
The invention uses conservative amino acid substitutions (such as H588Y, H588D, H588N, H588Q, H588R, H588K, H588F, H588W, H588L, H588M, H588P, H588S, H588T, H588V, H588A, H588G, H588I, H588C) that are pre-selected to maintain protein folding and structural integrity, cushioning against potential stability issues while achieving microglia targeting.
Data Source
AI summary
The present invention relates to adeno-associated virus (AAV) capsid proteins that have been modified to insert an amino acid sequence and/or methods of targeting microglia or brain macrophages using the AAV capsid proteins of the invention.