Variant AAV Capsids for Lung Cell Gene Delivery Under Immune Pressure
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Solution Overview
Problem
Existing adeno-associated virus (AAV) vectors face challenges in efficiently delivering genes to human lung cells due to anti-capsid immune responses, limited transduction of certain tissues, and inability for targeted delivery to specific cell types, which hinders effective gene therapy for pulmonary disorders.
Innovation Solution
Development of variant AAV capsid proteins with specific amino acid modifications, such as peptide insertions and substitutions, to enhance infectivity and resistance to human AAV neutralizing antibodies, allowing for improved delivery to lung cells, particularly airway epithelial cells.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type AAV capsid proteins are used, then safety is maintained, but infectivity to human lung cells is insufficient
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of the AAV capsid protein through directed evolution. Specifically, multiple point mutations were introduced into the cap gene to create variant capsid proteins with altered properties. The variant capsid protein exhibits at least 60% amino acid sequence identity to wild-type AAV2 capsid protein, balancing safety (maintained through high similarity) and improved infectivity (achieved through specific mutations that enhance lung cell targeting).
Solution Approach 2:
The patent uses copying by creating a variant capsid protein that replicates the essential safety features of wild-type AAV while incorporating beneficial mutations. The variant capsid maintains the basic structure and safety profile of wild-type AAV (non-pathogenic, no etiologic association with diseases) while copying only the necessary functional elements and adding improvements through directed evolution to achieve enhanced lung tropism.
2Duration of action of stationary object
If AAV vectors are used for gene delivery, then sustained transgene expression is achieved, but anti-capsid immune responses limit utility
Solution Approach 1:
The patent applies parameter changes by modifying the capsid protein sequence to alter its immunogenicity while preserving its function. The directed evolution process selected for variants that maintain sustained transgene expression capability while reducing recognition by pre-existing anti-AAV antibodies. The variant capsid protein achieves this through specific amino acid substitutions that change surface epitopes recognized by the immune system.
Solution Approach 2:
The patent converts the harmful effect of immune responses into a benefit by using the immune pressure as a selection criterion in directed evolution. The process exposed the capsid library to human serum containing neutralizing antibodies, and selected for variants that resisted neutralization. This transformed the previously harmful immune response into a useful selection pressure that identified capsid variants with improved ability to evade immune detection while maintaining transgene expression.
3Productivity
If AAV vectors are used, then gene delivery capability is achieved, but targeted delivery to specific cell types is limited
Solution Approach 1:
The patent applies local quality by introducing specific localized changes to the capsid protein structure through point mutations. These mutations are concentrated in specific regions of the capsid that are involved in cell surface receptor interactions. The directed evolution process identified mutations that specifically enhance binding to human lung epithelial cell surface molecules, creating localized functional improvements without altering the overall capsid structure or its ability to deliver genes to other tissues.
Data Source
AI summary
The present disclosure provides a variant AAV capsid protein that confers tropism to lung cells and recombinant adeno-associated viruses comprising the variant AAV capsid protein and pharmaceutical compositions comprising same and their use in the delivery of heterologous nucleic acids to lung cells for the treatment of pulmonary disorders.