State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, PR China; College of Veterinary Medicine, Huazhong Agricultural University, Wuhan, 430070, PR China; Key Laboratory of development of veterinary diagnostic products, Ministry of Agriculture, Wuhan, 430070, PR China.
State Key Laboratory of Agricultural Microbiology, Huazhong Agricultural University, Wuhan 430070, PR China.
EBioMedicine. 2021 May;67:103381. doi: 10.1016/j.ebiom.2021.103381. Epub 2021 May 14.
An ideal animal model to study SARS-coronavirus 2 (SARS-CoV-2) pathogenesis and evaluate therapies and vaccines should reproduce SARS-CoV-2 infection and recapitulate lung disease like those seen in humans. The angiotensin-converting enzyme 2 (ACE2) is a functional receptor for SARS-CoV-2, but mice are resistant to the infection because their ACE2 is incompatible with the receptor-binding domain (RBD) of the SARS-CoV-2 spike protein .
SARS-CoV-2 was passaged in BALB/c mice to obtain mouse-adapted virus strain. Complete genome deep sequencing of different generations of viruses was performed to characterize the dynamics of the adaptive mutations in SARS-CoV-2. Indirect immunofluorescence analysis and Biolayer interferometry experiments determined the binding affinity of mouse-adapted SARS-CoV-2 WBP-1 RBD to mouse ACE2 and human ACE2. Finally, we tested whether TLR7/8 agonist Resiquimod (R848) could also inhibit the replication of WBP-1 in the mouse model.
The mouse-adapted strain WBP-1 showed increased infectivity in BALB/c mice and led to severe interstitial pneumonia. We characterized the dynamics of the adaptive mutations in SARS-CoV-2 and demonstrated that Q493K and Q498H in RBD significantly increased its binding affinity towards mouse ACE2. Additionally, the study tentatively found that the TLR7/8 agonist Resiquimod was able to protect mice against WBP-1 challenge. Therefore, this mouse-adapted strain is a useful tool to investigate COVID-19 and develop new therapies.
We found for the first time that the Q493K and Q498H mutations in the RBD of WBP-1 enhanced its interactive affinities with mACE2. The mouse-adapted SARS-CoV-2 provides a valuable tool for the evaluation of novel antiviral and vaccine strategies. This study also tentatively verified the antiviral activity of TLR7/8 agonist Resiquimod against SARS-CoV-2 in vitro and in vivo.
This research was funded by the National Key Research and Development Program of China (2020YFC0845600) and Emergency Science and Technology Project of Hubei Province (2020FCA046) and Robert A. Welch Foundation (C-1565).
研究严重急性呼吸综合征冠状病毒 2（SARS-CoV-2）发病机制、评估治疗方法和疫苗的理想动物模型应能复制 SARS-CoV-2 感染，并重现人类肺部疾病。血管紧张素转化酶 2（ACE2）是 SARS-CoV-2 的功能性受体，但由于其 ACE2 与 SARS-CoV-2 刺突蛋白的受体结合域（RBD）不兼容，因此小鼠对该病毒具有抗性。
我们将 SARS-CoV-2 在 BALB/c 小鼠中传代，以获得适应小鼠的病毒株。对不同代次病毒的全基因组深度测序，以分析 SARS-CoV-2 适应性突变的动态变化。间接免疫荧光分析和生物层干涉实验测定了适应小鼠的 SARS-CoV-2 WBP-1 RBD 与小鼠 ACE2 和人 ACE2 的结合亲和力。最后，我们测试了 TLR7/8 激动剂瑞喹莫德（R848）是否也能抑制 WBP-1 在小鼠模型中的复制。
适应小鼠的 WBP-1 株在 BALB/c 小鼠中的感染性增强，导致严重的间质性肺炎。我们对 SARS-CoV-2 适应性突变的动态变化进行了特征分析，证明 RBD 中的 Q493K 和 Q498H 显著增加了其与小鼠 ACE2 的结合亲和力。此外，研究初步发现 TLR7/8 激动剂瑞喹莫德能够保护小鼠免受 WBP-1 攻击。因此，该适应小鼠的病毒株是研究 COVID-19 和开发新疗法的有用工具。
我们首次发现，WBP-1 的 RBD 中的 Q493K 和 Q498H 突变增强了其与 mACE2 的相互作用亲和力。适应小鼠的 SARS-CoV-2 为评估新型抗病毒和疫苗策略提供了有价值的工具。本研究还初步验证了 TLR7/8 激动剂瑞喹莫德在体外和体内对 SARS-CoV-2 的抗病毒活性。
本研究得到了中国国家重点研发计划（2020YFC0845600）和湖北省应急科技攻关项目（2020FCA046）以及罗伯特·A·韦尔奇基金会（C-1565）的资助。
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