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Optimization of Alpha-1 Antitrypsin Expression from Adeno-Associated Virus Vectors
Qiushi Tang1, Debora Pires-Ferreira1, Christian Mueller2
1Department of Genetic and Cellular Medicine, University of Massachusetts Chan Medical School, Worcester, Massachusetts, USA.
Human Gene Therapy
|May 20, 2026
Summary
Optimizing adeno-associated virus (AAV) vector design enhances alpha-1 antitrypsin (AAT) expression for treating AAT deficiency. Robust regulatory elements and single-stranded genomes yield the highest AAT expression, paving the way for safer gene therapies.
Area of Science:
- Gene Therapy
- Molecular Biology
- Genetic Disorders
Background:
- Alpha-1 antitrypsin deficiency (AATD) is an inherited disorder causing lung and liver disease due to SERPINA1 mutations.
- Adeno-associated virus (AAV)-mediated gene therapy aims for durable AAT expression but faces challenges in achieving therapeutic levels at safe doses.
Purpose of the Study:
- To evaluate AAV vector design strategies for enhancing AAT expression and potency.
- To identify key parameters for optimizing AAV vector design to reduce therapeutic doses for AATD.
Main Methods:
- Compared promoter/enhancer configurations, codon optimization, single-stranded vs. self-complementary genomes, and polyadenylation signals using AAV1 and AAV8 platforms.
- Evaluated an engineered oxidation-resistant AAT variant.
- Tested vector designs in mouse and ferret models.
Main Results:
- The chicken β-actin expression cassette significantly outperformed a liver-specific promoter in driving AAT levels.
- Codon optimization did not improve, and sometimes reduced, AAT expression; self-complementary AAV vectors showed lower expression than single-stranded ones.
- Modifications to polyadenylation signals or enhancers did not boost expression; an oxidation-resistant AAT variant yielded lower circulating levels.
Conclusions:
- Promoter strength and cassette architecture are critical determinants of AAV-mediated AAT expression potency.
- Full-length, single-stranded AAV vectors with strong regulatory elements provide the highest *in vivo* AAT expression.
- Findings provide a foundation for developing next-generation AAV vectors for safer and more effective AATD treatment.
