Li Chengwen, Hirsch Matt, DiPrimio Nina, Asokan Aravind, Goudy Kevin, Tisch Roland, Samulski R Jude
Gene Therapy Center, University of North Carolina at Chapel Hill, Chapel Hill, NC 27599, USA.
J Virol. 2009 Jul;83(13):6817-24. doi: 10.1128/JVI.00278-09. Epub 2009 Apr 15.
A recent clinical trial in patients with hemophilia B has suggested that adeno-associated virus (AAV) capsid-specific cytotoxic T lymphocytes (CTLs) eliminated AAV-transduced hepatocytes and resulted in therapeutic failure. AAV capsids elicit a CTL response in animal models; however, these capsid-specific CTLs fail to kill AAV-transduced target cells in mice. To better model the human clinical trial data in mice, we introduced an immunodominant epitope derived from ovalbumin (OVA; SIINFEKL) into the AAV capsid and tested CTL-mediated killing of AAV2-transduced target tissues in vivo. Initially, in vitro experiments demonstrated both classical class I and cross-presentation of the OVA antigen, following endogenous expression or AAV2-OVA vector transduction, respectively. Furthermore, an OVA-specific CTL response was elicited after muscular or systemic injection of the AAV2-OVA vector. Finally, CTL reactivity was enhanced in mice with established SIINFEKL-specific immunity after AAV2-OVA/alpha1 anti-trypsin (AAT) administration. Most importantly, these OVA-specific CTLs decreased AAT expression in mice treated with AAV2-OVA/AAT vector that followed a time course mimicking uncoating kinetics of AAV2 transduction in OVA-immunized mice. These results demonstrate that AAV capsid-derived antigens elicit CD8(+) CTL reactivity, and these CTLs eliminated AAV-transduced target cells in mice. Notably, this model system can be exploited to study the kinetics of capsid presentation from different serotypes of AAV and permit the design of novel strategies to block CTL-mediated killing of AAV-transduced cells.
最近一项针对乙型血友病患者的临床试验表明，腺相关病毒（AAV）衣壳特异性细胞毒性T淋巴细胞（CTL）清除了AAV转导的肝细胞，导致治疗失败。AAV衣壳在动物模型中引发CTL反应；然而，这些衣壳特异性CTL无法杀死小鼠体内AAV转导的靶细胞。为了在小鼠中更好地模拟人类临床试验数据，我们将源自卵清蛋白（OVA；SIINFEKL）的免疫显性表位引入AAV衣壳，并在体内测试了CTL介导的对AAV2转导靶组织的杀伤作用。最初，体外实验分别在内源表达或AAV2-OVA载体转导后，证明了OVA抗原的经典I类和交叉呈递。此外，肌肉或全身注射AAV2-OVA载体后引发了OVA特异性CTL反应。最后，在给予AAV2-OVA/α1抗胰蛋白酶（AAT）后，在已建立SIINFEKL特异性免疫的小鼠中CTL反应性增强。最重要的是，这些OVA特异性CTL降低了用AAV2-OVA/AAT载体处理的小鼠中AAT的表达，其时间进程模拟了OVA免疫小鼠中AAV2转导的脱壳动力学。这些结果表明，AAV衣壳衍生的抗原引发CD8(+) CTL反应性，并且这些CTL清除了小鼠体内AAV转导的靶细胞。值得注意的是，该模型系统可用于研究不同血清型AAV衣壳呈递的动力学，并允许设计新策略来阻断CTL介导的对AAV转导细胞的杀伤作用。
