Chromosomal Integration of Adenoviral Vector DNA In Vivo

Abstract

ABSTRACT So far there has been no report of any clinical or preclinical evidence for chromosomal vector integration following adenovirus (Ad) vector-mediated gene transfer in vivo . We used liver gene transfer with high-capacity Ad vectors in the FAH Δexon5 mouse model to analyze homologous and heterologous recombination events between vector and chromosomal DNA. Intravenous injection of Ad vectors either expressing a fumarylacetoacetate hydrolase (FAH) cDNA or carrying part of the FAH genomic locus resulted in liver nodules of FAH-expressing hepatocytes, demonstrating chromosomal vector integration. Analysis of junctions between vector and chromosomal DNA following heterologous recombination indicated integration of the vector genome through its termini. Heterologous recombination occurred with a median frequency of 6.72 × 10 −5 per transduced hepatocyte, while homologous recombination occurred more rarely with a median frequency of 3.88 × 10 −7 . This study has established quantitative and qualitative data on recombination of adenoviral vector DNA with genomic DNA in vivo , contributing to a risk-benefit assessment of the biosafety of Ad vector-mediated gene transfer.