Infection by SARS-CoV-2 is dependent on binding of the viral spike protein to angiotensin converting enzyme 2 (ACE2), a membrane glycoprotein expressed on epithelial cells in the human upper respiratory tract. Recombinant ACE2 protein has potential application for anti-viral therapy. Here we co-transfected mouse fibroblasts (A9 cells) with a cloned fragment of human genomic DNA containing the intact ACE2 gene and an unlinked neomycin phosphotransferase gene, and then selected stable neomycin-resistant transfectants. Transfectant clones expressed ACE2 protein at levels that were generally proportional to the number of ACE2 gene copies integrated in the cell genome, ranging up to approximately 50 times the level of ACE2 present of Vero-E6 cells. Cells overexpressing ACE2 were hypersensitive to infection by spike-pseudotyped vesicular stomatitis virus (VSV-S), and adsorption of VSV-S to these cells occurred at an accelerated rate compared to Vero-E6 cells. The transfectant cell clones described here therefore have favorable attributes as feedstocks for large-scale production of recombinant human ACE2 protein.

SARS-CoV-2 的感染取决于病毒刺突蛋白与血管紧张素转换酶 2 (ACE2) 的结合，血管紧张素转换酶 2 是一种在人类上呼吸道上皮细胞上表达的膜糖蛋白。重组ACE2蛋白在抗病毒治疗方面具有潜在的应用前景。在这里，我们用含有完整 ACE2 基因和未连接的新霉素磷酸转移酶基因的人类基因组 DNA 克隆片段共转染小鼠成纤维细胞（A9 细胞），然后选择稳定的新霉素抗性转染子。转染子克隆表达的 ACE2 蛋白水平通常与细胞基因组中整合的 ACE2 基因拷贝数成正比，最高可达 Vero-E6 细胞中 ACE2 水平的约 50 倍。过表达 ACE2 的细胞对刺突假型水泡性口炎病毒 (VSV-S) 的感染高度敏感，并且与 Vero-E6 细胞相比，这些细胞对 VSV-S 的吸附速度更快。因此，本文描述的转染细胞克隆具有作为大规模生产重组人 ACE2 蛋白的原料的有利属性。