AAV PHP.S-CAG-Cre

Gene therapy broadly describes the strategy of introducing genetic material into target cells to treat or cure disease. Among the approaches currently being explored, recombinant adeno-associated viral vectors (rAAV) have emerged as one of the most promising candidates. Adeno-associated virus (AAV) is a member of the Parvoviridae family and was originally discovered as a contaminant in simian adenovirus preparations. AAV is a small, icosahedral, nonenveloped virus of approximately 25 nm in diameter containing a single-stranded DNA genome that is distinct from other members of the Parvoviridae family in that it is unable to replicate without the assistance of a helper virus such as adenovirus (Ad), herpes simplex virus (HSV), human papillomavirus (HPV), or vaccinia virus. In addition, AAV can confer long-term gene expression, has a range of serotypes that collectively share a range of tissue tropisms, and can package any transgene flanked by the AAV inverted terminal repeats (ITRs) with a total genome size of no more than ∼5 kb. All of these properties make AAV an excellent candidate for therapeutic gene delivery.

The AAV genome consists of rep and capsid genes flanked by 2 inverted terminal repeats. AAV vectors have been successfully used in multiple clinical trials for patients with Leber congenital amaurosis and hemophilia B. The use of AAV vectors for gene delivery is attractive because of their ability to transduce both dividing and non-dividing cells, ease of production, long-term transgene expression, and lack of pathogenicity. AAV vectors are constructed by replacing the rep and capsid genes with the therapeutic gene. AAV transduction involves several steps, including AAV binding to the target cell surface, receptor-mediated endocytosis into endosomes and lysosomes, perinuclear accumulation, entry into the nucleus and uncoating within the nucleus, and second-strand synthesis prior to transgene expression.