Contaminating plasmid sequences and disrupted vector genomes in the liver following adeno-associated virus gene...

Area of Science:

• Molecular Biology
• Hepatology
• Gene Therapy

Background:

• Adeno-associated viruses (AAVs) are widely used gene therapy vectors.
• AAV administration can lead to significant liver complications.
• The precise mechanisms of AAV-induced liver toxicity are not well understood.

Purpose of the Study:

• To investigate the molecular basis of liver toxicity in a patient receiving AAV gene therapy.
• To identify potential contributing factors to AAV-related hepatitis.

Main Methods:

• Case study of a child with spinal muscular atrophy type 1 post-onasemnogene abeparvovec treatment.
• Long- and short-read metagenomic sequencing of liver tissue.
• Analysis of vector genome integrity and host-pathogen interactions.

Main Results:

• Complex, recombined manufacturing plasmid sequences were detected in the liver.
• AAV vector genomes showed extensive disruption, concatemerization, and vector-human DNA junctions.
• Human betaherpesvirus 6B was identified in the liver tissue.

Conclusions:

• The study identified complex DNA structures, including recombined plasmid sequences and rearranged vector genomes, in the liver of a patient experiencing AAV gene therapy-related hepatitis.
• The presence of manufacturing plasmid sequences and human betaherpesvirus 6B warrants further investigation.
• These findings suggest potential mechanisms for AAV-induced liver toxicity that require validation in larger patient cohorts.