The spread of SARS-CoV-2, the virus that causes Coronavirus Disease 2019 (COVID-19), has been characterized as a worldwide pandemic. Currently, there are few preclinical animal models that suitably represent infection, as the main point of entry to human cells is via human angiotensin-converting enzyme 2 (ACE2) which is not present in typical preclinical mouse strains. Additionally, SARS-CoV-2 is highly virulent and unsafe for use in many research facilities. Here we describe the development of a preclinical animal model using intranasal administration of ACE2 followed by non-infectious SARS-CoV-2 pseudovirus (PsV) challenge. To specifically generate our SARS-CoV-2 PsV, we used a lentivirus system. Following co-transfection with a packaging plasmid containing HIV Gag and Pol, luciferase-expressing lentiviruses, and a plasmid carrying the SARS-CoV-2 spike protein, SARS-CoV-2 PsVs can be isolated and purified. To better understand and maximize the infectivity of SARS-CoV-2 PsV, we generated PsV carrying spike protein variants known to have varying human ACE2 binding properties, including 19 deletion (19del) and 19del + D614G. Our system demonstrated the ability of PsVs to infect the respiratory passage of mice following intranasal hACE2 transduction. Additionally, we demonstrate in vitro and in vivo manipulability of our system using recombinant receptor-binding domain protein to prevent PsV infection. Our PsV system is able to model SARS-CoV-2 infections in a preclinical mouse model and can be used to test interventions or preventative treatments. We believe that this method can be extended to work in various mouse strains or to model infection with different coronaviruses. A simple in vivo system such as our model is crucial for rapidly and effectively responding to the current COVID-19 pandemic in addition to preparing for future potential coronavirus outbreaks.

中文翻译：

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一种新型基于假病毒的 SARS-CoV-2 感染小鼠模型，用于测试 COVID-19 干预措施


引起 2019 年冠状病毒病 (COVID-19) 的病毒 SARS-CoV-2 的传播已被定性为全球大流行。目前，很少有合适代表感染的临床前动物模型，因为进入人体细胞的主要点是通过人血管紧张素转换酶 2 (ACE2)，而典型的临床前小鼠品系中不存在这种酶。此外，SARS-CoV-2 具有高毒力，在许多研究机构中使用并不安全。在此，我们描述了通过鼻内给予 ACE2，然后进行非传染性 SARS-CoV-2 假病毒 (PsV) 攻击的临床前动物模型的开发。为了专门生成 SARS-CoV-2 PsV，我们使用了慢病毒系统。用含有 HIV Gag 和 Pol 的包装质粒、表达荧光素酶的慢病毒和携带 SARS-CoV-2 刺突蛋白的质粒共转染后，可以分离和纯化 SARS-CoV-2 PsV。为了更好地了解并最大限度地提高 SARS-CoV-2 PsV 的感染性，我们生成了携带已知具有不同人类 ACE2 结合特性的刺突蛋白变体的 PsV，包括 19 缺失 (19del) 和 19del + D614G。我们的系统证明了 PsV 在鼻内 hACE2 转导后感染小鼠呼吸道的能力。此外，我们还证明了我们的系统使用重组受体结合域蛋白来预防 PsV 感染的体外和体内可操作性。我们的 PsV 系统能够在临床前小鼠模型中模拟 SARS-CoV-2 感染，并可用于测试干预措施或预防性治疗。我们相信这种方法可以扩展到在各种小鼠品系中发挥作用或模拟不同冠状病毒的感染。 除了为未来潜在的冠状病毒爆发做好准备之外，像我们的模型这样的简单体内系统对于快速有效地应对当前的 COVID-19 大流行至关重要。