AAV serotype 2 vectors preferentially integrate into active genes in mice

• Published in: Nature genetics Vol. 34; no. 3; pp. 297 - 302
• Main Authors: Nakai, Hiroyuki, Montini, Eugenio, Fuess, Sally, Storm, Theresa A, Grompe, Markus, Kay, Mark A
• Format: Journal Article
• Language: English
• Published: New York Nature Publishing Group US 01.07.2003; Nature Publishing Group
• Subjects: Adenoviruses; Agriculture; Animal Genetics and Genomics; Animals; Base Sequence; Biological and medical sciences; Biomedical and Life Sciences; Biomedicine; Cancer Research; Cell Line; Chromosome Deletion; Chromosomes; Chromosomes - genetics; Dependovirus - genetics; Female; Fundamental and applied biological sciences. Psychology; Gene Function; Gene therapy; Gene Transfer Techniques; Genes - genetics; Genetic aspects; Genetic Therapy; Genetic Vectors; Health aspects; Hepatocytes - transplantation; Human Genetics; Humans; letter; Liver; Methods; Mice; Mice, Inbred C57BL; Molecular and cellular biology; Molecular Sequence Data; Plasmids; Sequence Homology, Nucleic Acid; Transduction, Genetic; Transgenes - genetics; Virus Integration; United States; Genetics
• ISSN: 1061-4036; 1546-1718
• DOI: 10.1038/ng1179

Recombinant adeno-associated virus serotype 2 (rAAV2) is a promising vector for gene therapy because it can achieve long-term stable transgene expression in animals and human subjects after direct administration of vectors into various target tissues 1 . In the liver, although stable transgene expression primarily results from extrachromosomal vector genomes 2 , a series of experiments has shown that vector genomes integrate into host chromosomes in hepatocytes 3 , 4 , 5 at a low frequency 2 . Despite the low integration efficiency, recent reports of retroviral insertional mutagenesis in mice 6 and two human subjects 7 , 8 have raised concerns about the potential for rAAV2-mediated insertional mutagenesis. Here we characterize rAAV2-targeted chromosomal integration sites isolated from selected or non-selected hepatocytes in vector-injected mouse livers. We document frequent chromosomal deletions of up to 2 kb at integration sites (14 of 14 integrations, 100%; most of the deletions were <0.3 kb) and preferred integration into genes (21 of 29 integrations, 72%). In addition, all of the targeted genes analyzed (20 of 20 targeted genes, 100%) were expressed in the liver. This is the first report to our knowledge on host chromosomal effects of rAAV2 integration in animals, and it provides insights into the nature of rAAV2 vector integration into chromosomes in quiescent somatic cells in animals and human subjects.