Li Hua, Lin Shih-Wen, Giles-Davis Wynetta, Li Yan, Zhou Dongming, Xiang Zhi Quan, High Katherine A, Ertl Hildegund C J
Wistar Institute, Philadelphia, Pennsylvania, USA.
Mol Ther. 2009 Jul;17(7):1215-24. doi: 10.1038/mt.2009.79. Epub 2009 Apr 14.
Hepatic adeno-associated virus (AAV)-serotype 2-mediated gene transfer results in sustained transgene expression in experimental animals but not in human subjects. We hypothesized that loss of transgene expression in humans might be caused by immune memory mechanisms that become reactivated upon AAV vector transfer. Here, we tested the effect of immunological memory to AAV capsid on AAV-mediated gene transfer in a mouse model. Upon hepatic transfer of an AAV2 vector expressing human factor IX (hF.IX), mice immunized with adenovirus (Ad) vectors expressing AAV8 capsid before AAV2 transfer developed less circulating hF.IX and showed a gradual loss of hF.IX gene copies in liver cells as compared to control animals. This was not observed in mice immunized with an Ad vectors expressing AAV2 capsid before transfer of rAAV8-hF.IX vectors. The lower hF.IX expression was primarily linked to AAV-binding antibodies that lacked AAV-neutralizing activity in vitro rather than to AAV capsid-specific CD8(+) T cells.
肝相关腺病毒（AAV）2型介导的基因转移在实验动物中可导致转基因持续表达，但在人类受试者中却并非如此。我们推测，人类中转基因表达的丧失可能是由免疫记忆机制引起的，这种机制在AAV载体转移后会重新激活。在此，我们在小鼠模型中测试了针对AAV衣壳的免疫记忆对AAV介导的基因转移的影响。在用表达人因子IX（hF.IX）的AAV2载体进行肝脏转移后，与对照动物相比，在转移AAV2之前用表达AAV8衣壳的腺病毒（Ad）载体免疫的小鼠，其循环中的hF.IX水平较低，并且肝细胞中的hF.IX基因拷贝数逐渐减少。在用表达AAV2衣壳的Ad载体免疫的小鼠中，在转移rAAV8-hF.IX载体之前未观察到这种情况。较低的hF.IX表达主要与体外缺乏AAV中和活性的AAV结合抗体有关，而不是与AAV衣壳特异性CD8(+) T细胞有关。
