Hemizygous mice are viable and fertile with no reported phenotypic abnormalities from the insertion of multiple full-length human AAVS1 sites (adeno-associated virus integration site 1) at a single chromosomal locus. The multiple (approximately five) AAVS1 loci within the transgene allow site-specific integration of hybrid vectors containing AAV inverted terminal repeat-flanked genes of interest.
Adeno-associated virus (AAV) is a nonpathogenic parvovirus with a single-stranded DNA genome (4.7 kb) containing two genes (rep and cap) flanked by 145-base inverted terminal repeats (ITRs). Efficient replication of the AAV genome occurs in the presence of a helper virus, either adenovirus or herpes simplex virus. In the absence of a helper virus, ITRs and Rep proteins are sufficient to mediate the integration of AAV sequences into a specific AAVS1 site in the host cell genome and thereby establish a latent infection. In addition, low levels of helper-independent AAV replication can also occur in cells that are chemically synchronized to the S phase or exposed to toxic conditions, including UV irradiation, heat, or carcinogens. Because of this, the AAVS1 loci within the transgene are a platform for site-specific integration of AAV ITR-flanked hybrid vectors that contain genes of interest.
