Severance Biomedical Science Institute, Graduate School of Medical Science, Brain Korea 21 Project, Yonsei University College of Medicine, Seoul, South Korea.
Division of Cancer Biology, Research Institute, National Cancer Center, Goyang, Gyeonggi, South Korea.
Front Immunol. 2022 Nov 15;13:1055811. doi: 10.3389/fimmu.2022.1055811. eCollection 2022.
Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) causing coronavirus disease 2019 (COVID-19) has been a global health concern since 2019. The viral spike protein infects the host by binding to angiotensin-converting enzyme 2 (ACE2) expressed on the cell surface, which is then processed by type II transmembrane serine protease. However, ACE2 does not react to SARS-CoV-2 in inbred wild-type mice, which poses a challenge for preclinical research with animal models, necessitating a human ACE2 (hACE2)-expressing transgenic mouse model. Cytokeratin 18 () promoter-derived hACE2 transgenic mice [B6.Cg-Tg(K18-ACE2)2Prlmn/J] are widely used for research on SARS-CoV-1, MERS-CoV, and SARS-CoV-2. However, SARS-CoV-2 infection is lethal at ≥10 PFU and SARS-CoV-2 target cells are limited to type-1 alveolar pneumocytes in K18-hACE2 mice, making this model incompatible with infections in the human lung. Hence, we developed lung-specific SARS-CoV-2 infection mouse models with surfactant protein B () and secretoglobin family 1a member 1 () promoters. After inoculation of 10 PFU of SARS-CoV-2 to the K18-hACE2, SFTPB-hACE2, and SCGB1A1-hACE2 models, the peak viral titer was detected at 2 days post-infection and then gradually decreased. In K18-hACE2 mice, the body temperature decreased by approximately 10°C, body weight decreased by over 20%, and the survival rate was reduced. However, SFTPB-hACE2 and SCGB1A1-hACE2 mice showed minimal clinical signs after infection. The virus targeted type I pneumocytes in K18-hACE2 mice; type II pneumocytes in SFTPB-hACE2 mice; and club, goblet, and ciliated cells in SCGB1A1-hACE2 mice. A time-dependent increase in severe lung lesions was detected in K18-hACE2 mice, whereas mild lesions developed in SFTPB-hACE2 and SCGB1A1-hACE2 mice. Spleen, small intestine, and brain lesions developed in K18-hACE2 mice but not in SFTPB-hACE2 and SCGB1A1-hACE2 mice. These newly developed SFTPB-hACE2 and SCGB1A1-hACE2 mice should prove useful to expand research on hACE2-mediated respiratory viruses.
严重急性呼吸综合征冠状病毒 2(SARS-CoV-2)引起的 2019 年冠状病毒病(COVID-19)自 2019 年以来一直是全球关注的健康问题。病毒的刺突蛋白通过与细胞表面表达的血管紧张素转化酶 2(ACE2)结合来感染宿主,然后由 II 型跨膜丝氨酸蛋白酶处理。然而,内源性野生型小鼠对 SARS-CoV-2 没有反应,这给动物模型的临床前研究带来了挑战,因此需要使用表达人 ACE2(hACE2)的转基因小鼠模型。角蛋白 18()启动子衍生的 hACE2 转基因小鼠[B6.Cg-Tg(K18-ACE2)2Prlmn/J]广泛用于研究 SARS-CoV-1、MERS-CoV 和 SARS-CoV-2。然而,SARS-CoV-2 在≥10 PFU 时具有致死性,并且 SARS-CoV-2 的靶细胞仅限于 K18-hACE2 小鼠中的 I 型肺泡型细胞,这使得该模型与人类肺部感染不兼容。因此,我们使用表面活性剂蛋白 B()和分泌球蛋白家族 1a 成员 1()启动子开发了肺特异性 SARS-CoV-2 感染小鼠模型。将 10 PFU 的 SARS-CoV-2 接种到 K18-hACE2、SFTPB-hACE2 和 SCGB1A1-hACE2 模型中后,在感染后 2 天检测到病毒滴度峰值,然后逐渐下降。在 K18-hACE2 小鼠中,体温下降约 10°C,体重下降超过 20%,存活率降低。然而,SFTPB-hACE2 和 SCGB1A1-hACE2 小鼠感染后仅出现轻微的临床症状。病毒靶向 K18-hACE2 小鼠中的 I 型肺泡型细胞;SFTPB-hACE2 小鼠中的 II 型肺泡型细胞;以及 SCGB1A1-hACE2 小鼠中的 club、goblet 和 ciliated 细胞。在 K18-hACE2 小鼠中检测到严重肺部病变的时间依赖性增加,而 SFTPB-hACE2 和 SCGB1A1-hACE2 小鼠中则发展为轻度病变。K18-hACE2 小鼠中脾、小肠和脑组织发生病变,但 SFTPB-hACE2 和 SCGB1A1-hACE2 小鼠中未发生病变。这些新开发的 SFTPB-hACE2 和 SCGB1A1-hACE2 小鼠应该有助于扩展对 hACE2 介导的呼吸道病毒的研究。