Peden Carmen S, Manfredsson Fredric P, Reimsnider Sharon K, Poirier Amy E, Burger Corinna, Muzyczka Nicholas, Mandel Ronald J
Department of Neuroscience, University of Florida College of Medicine, Gainesville, Florida, USA.
Mol Ther. 2009 Mar;17(3):524-37. doi: 10.1038/mt.2008.284. Epub 2009 Jan 13.
Recombinant adeno-associated virus (rAAV) expresses no viral genes after transduction. In addition, because the brain is relatively immunoprivileged, intracranial rAAV transduction may be immunologically benign due to a lack of antigen presentation. However, preexposure to AAV allows neutralizing antibodies (nAbs) to block brain transduction and rAAV readministration in the brain leads to an inflammatory response in the second-injection site. In this study, we replicate our striatal rAAV2/2-GDNF readministration results and extend this effect to a second transgene, green fluorescent protein (GFP). Unlike rAAV2/2-GDNF readministration, striatal rAAV2/2-GFP readministration leads to a loss of transgene in the second site in the absence of detectable circulating nAbs. In order to determine whether the transgene or the AAV2 capsid is the antigenic stimulus in brain for the immune response in the second site, we readministered rAAV2/2-GFP using two different rAAV serotypes (rAAV2/2 followed by rAAV2/5). In this case, there was no striatal inflammation or transgene loss detected in the second-injection site. In addition, striatal readministration of rAAV2/5-GFP also resulted in no detectable immune response. Furthermore, delaying rAAV2/2 striatal readministration to a 11-week interval abrogated the immune response in the second-injection site. Finally, while striatal readministration of rAAV2/2 leads to significant loss of transgene in the second-injection site, this effect is not due to loss of vector genomes as determined by quantitative real-time PCR. We conclude that intracellular processing of AAV capsids after transduction is the immunogenic antigen and capsid serotypes that are processed more quickly than rAAV2/2 are less immunogenic.
重组腺相关病毒（rAAV）转导后不表达病毒基因。此外，由于大脑相对具有免疫特权，颅内rAAV转导可能因缺乏抗原呈递而在免疫方面是良性的。然而，预先接触AAV会使中和抗体（nAbs）阻断大脑转导，并且在大脑中再次给予rAAV会导致第二次注射部位出现炎症反应。在本研究中，我们重复了纹状体rAAV2/2 - GDNF再次给药的结果，并将这种效应扩展到第二个转基因绿色荧光蛋白（GFP）。与rAAV2/2 - GDNF再次给药不同，在没有可检测到的循环nAbs的情况下，纹状体rAAV2/2 - GFP再次给药会导致第二个部位的转基因丢失。为了确定转基因还是AAV2衣壳是大脑中第二次注射部位免疫反应的抗原刺激物，我们使用两种不同的rAAV血清型（rAAV2/2后接rAAV2/5）再次给予rAAV2/2 - GFP。在这种情况下，在第二次注射部位未检测到纹状体炎症或转基因丢失。此外，纹状体再次给予rAAV2/5 - GFP也未导致可检测到的免疫反应。此外，将rAAV2/2纹状体再次给药的时间间隔延长至11周可消除第二次注射部位的免疫反应。最后，虽然纹状体再次给予rAAV2/2会导致第二次注射部位的转基因显著丢失，但通过定量实时PCR确定，这种效应并非由于载体基因组的丢失。我们得出结论，转导后AAV衣壳的细胞内加工是免疫原性抗原，并且比rAAV2/2加工更快的衣壳血清型免疫原性更低。
