Xia H, Anderson B, Mao Q, Davidson B L
Program in Gene Therapy, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City, Iowa 52242, USA.
J Virol. 2000 Dec;74(23):11359-66. doi: 10.1128/jvi.74.23.11359-11366.2000.
Some inborn errors of metabolism due to deficiencies of soluble lysosomal enzymes cause global neurodegenerative disease. Representative examples include the infantile and late infantile forms of the ceroid lipofuscinoses (CLN1 or CLN2 deficiency, respectively) and mucopolysaccharidoses type VII (MPS VII), a deficiency of beta-glucuronidase. Treatment of the central nervous system component of these disorders will require widespread protein or enzyme replacement, either through dissemination of the protein or through dissemination of a gene encoding it. We hypothesize that transduction of brain microcapillary endothelium (BME) with recombinant viral vectors, with secretion of enzyme product basolaterally, could allow for widespread enzyme dissemination. To achieve this, viruses should be modified to target the BME. This requires (i) identification of a BME-resident target receptor, (ii) identification of motifs targeted to that molecule, (iii) the construction of modified viruses to allow for binding to the target receptor, and (iv) demonstrated transduction of receptor-expressing cells. In proof of principal experiments, we chose the human transferrin receptor (hTfR), a molecule found at high density on human BME. A nonamer phage display library was panned for motifs which could bind hTfR. Forty-three clones were sequenced, most of which contained an AKxxK/R, KxKxPK/R, or KxK motif. Ten peptides representative of the three motifs were cloned into the HI loop of adenovirus type 5 fiber. All motifs tested retained their ability to trimerize and bind transferrin receptor, and seven allowed for recombinant adenovirus production. Importantly, the fiber-modified viruses facilitated increased gene transfer (2- to 34-fold) to hTfR expressing cell lines and human brain microcapillary endothelia expressing high levels of endogenous receptor. Our data indicate that adenoviruses can be modified in the HI loop for expanded tropism to the hTfR.
一些由于可溶性溶酶体酶缺乏引起的先天性代谢缺陷会导致全身性神经退行性疾病。典型例子包括类蜡样脂褐质沉积症的婴儿型和晚婴儿型（分别为CLN1或CLN2缺乏症）以及黏多糖贮积症VII型（MPS VII），即β-葡萄糖醛酸酶缺乏症。治疗这些疾病的中枢神经系统部分将需要通过蛋白质或酶的广泛替代，要么通过蛋白质的扩散，要么通过编码该蛋白质的基因的扩散。我们假设用重组病毒载体转导脑微血管内皮细胞（BME），并使其酶产物从基底外侧分泌，可实现酶的广泛扩散。要实现这一点，病毒应进行修饰以靶向BME。这需要（i）鉴定一种BME驻留靶受体，（ii）鉴定靶向该分子的基序，（iii）构建修饰病毒以使其能够与靶受体结合，以及（iv）证明对表达受体的细胞进行转导。在原理验证实验中，我们选择了人转铁蛋白受体（hTfR），一种在人BME上高密度存在的分子。用一个九聚体噬菌体展示文库筛选能够结合hTfR的基序。对43个克隆进行了测序，其中大多数包含AKxxK/R、KxKxPK/R或KxK基序。代表这三个基序的10个肽被克隆到5型腺病毒纤维的HI环中。所有测试的基序都保留了三聚化和结合转铁蛋白受体的能力，并且有7个允许产生重组腺病毒。重要的是，纤维修饰的病毒促进了向表达hTfR的细胞系和表达高水平内源性受体的人脑微血管内皮细胞的基因转移增加（2至34倍）。我们的数据表明，腺病毒可以在HI环中进行修饰，以扩大对hTfR的嗜性。
