Gene transfer into skeletal muscle using novel AAV serotypes.

Area of Science:

• Molecular Biology
• Gene Therapy
• Virology

Background:

• Skeletal muscle is a significant target for gene delivery due to its large mass and accessibility.
• Adeno-associated virus (AAV) vectors are effective for skeletal muscle transduction, enabling stable and safe transgene expression.
• While AAV serotype 2 has been widely used, newer serotypes like AAV1 demonstrate superior muscle transduction efficiency.

Purpose of the Study:

• To compare the gene transfer efficiencies of novel adeno-associated virus (AAV) serotypes (AAV2/7 and AAV2/8) against established serotypes in skeletal muscle.
• To evaluate the efficacy of different pseudotyped AAV serotypes in transducing various muscle fiber types in immunocompetent mice.

Main Methods:

• Injection of pseudotyped AAV serotypes (AAV2/1, AAV2/2, AAV2/5, AAV2/7, AAV2/8) into three distinct muscles of C57BL/6 mice.
• Quantitative comparison of gene transfer efficiencies across different AAV serotypes.
• Assessment of transduction in both slow and fast-twitch skeletal muscle fibers at a consistent vector titer.

Main Results:

• AAV2/7 and AAV2/8 demonstrated transduction efficiencies comparable to AAV2/1 and superior to AAV2/2 and AAV2/5 in skeletal muscle.
• All tested AAV serotypes effectively transduced both slow and fast muscle fibers at the administered vector dose.
• Transgene expression was sustained throughout the study duration, with minimal inflammatory responses observed across serotypes.

Conclusions:

• AAV2/7 and AAV2/8 are highly efficient in transducing skeletal muscle fibers in immunocompetent mice.
• These novel AAV serotypes present significant potential for advancing gene transfer strategies in skeletal muscle.
• The findings expand the toolkit for skeletal muscle-targeted gene therapy applications.