遺伝子導入法

—AAVベクターを用いた遺伝子治療法の開発—

抄録

Adeno-associated virus (AAV) is a human parvovirus with a single-strand DNA genome of approximately 4.6 kb encapsulated in an icosahedral virion 20 to 26 nm in diameter. Recombinant AAV vectors have promising features as a vector for gene therapy, such as the lack of any apparent pathogenicity, low immunogenicity, and relatively high stability of transgene expression. Preclinical studies have been performed for the treatment of cystic fibrosis, Fanconi anemia, β-thalassemia, hemophilia, AIDS, Parkinson disease, and many kinds of neoplastic diseases such as malignant brain tumors. Here, we introduced gene therapy using AAV vectors containing herpes simplex virus-thymidine kinase (HS-tk) gene or cytokine genes. To produce gliorna in the brain of nude mice, we injected the cells suspended in PBS into the brain. Then we injected AAV-tk (9.6 × 10⁹ particles in 2 μl) was injected into the brain where glioma cells had been transplanted on day 7 (single injection) or on day 7, 10, and 13 (multiple injections). In the case of a single injection, 100 mg/kg ganciclovir (GCV) was administered ip, twice daily, in 0.5 ml saline, for 6 days after vector injection. Following multiple injections, the same volume of GCV was administered ip, twice daily, in 0.5 ml saline, for 2 days after vector injection and the procedure was repeated three times. When we injected AAV-tk three times, the tumors disappeared completely. Even when we injected the AAV vector once, the tumor size was much smaller than that of control. In the case of interferon-β gene, we got almost same antitumor effect. From these results, AAV vectors could be more efficiently transduced to congenital and acquired diseases than ordinary gene transfer techniques.