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The pathogenicity of SARS-CoV-2 in hACE2 transgenic mice

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Severe acute respiratory syndrome CoV-2 (SARS-CoV-2) caused the corona virus disease 2019 (COVID-19) cases in China and has become a public health emergency of international concern1. Because angiotensin-converting enzyme 2 (ACE2) is the cell entry receptor of SARS-CoV5, we used transgenic mice bearing human ACE2 and infected with SARS-CoV-2 to study the pathogenicity of the virus. Weight loss and virus replication in lung were observed in hACE2 mice infected with SARS-CoV-2. The typical histopathology was interstitial pneumonia with infiltration of significant macrophages and lymphocytes into the alveolar interstitium, and accumulation of macrophages in alveolar cavities. Viral antigens were observed in the bronchial epithelial cells, macrophages and alveolar epithelia. The phenomenon was not found in wild-type mice with SARS-CoV-2 infection. Notably, we have confirmed the pathogenicity of SARS-CoV-2 in hACE2 mice. The mouse model with SARS-CoV-2 infection will be valuable for evaluating antiviral therapeutics and vaccines as well as understanding the pathogenesis of COVID-19.
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830 | Nature | Vol 583 | 30 July 2020
Article
The pathogenicity of SARS-CoV-2 in hACE2
transgenic mice
Linlin Bao1,2,6, Wei Deng1,2,6, Baoying Huang3,6, Hong Gao1,2,6, Jiangning Liu1,2,6, Lili Ren4,
Qiang Wei1,2, Pin Yu1,2, Yanfeng Xu1,2, Feifei Qi1,2, Yajin Qu1,2, Fengdi Li1,2, Qi Lv1,2, Wenling Wang3,
Jing Xue1,2, Shuran Gong1,2, Mingya Liu1,2, Guanpeng Wang1,2, Shunyi Wang1,2, Zhiqi Song1,2,
Linna Zhao1,2, Peipei Liu3, Li Zhao3, Fei Ye3, Huijuan Wang3, Weimin Zhou3, Na Zhu3, Wei Zhen3,
Haisheng Yu1,2, Xiaojuan Zhang1,2, Li Guo4, Lan Chen4, Conghui Wang4, Ying Wang4,
Xinming Wang4, Yan Xiao4, Qiangming Sun5, Hongqi Liu5, Fanli Zhu5, Chunxia Ma5,
Lingmei Yan5, Mengli Yang5, Jun Han3, Wenbo Xu3, Wenjie Tan3, Xiaozhong Peng5, Qi Jin4,
Guizhen Wu3 ✉ & Chuan Qin1,2 ✉
Severe acute respiratory syndrome coronavirus2 (SARS-CoV-2) is the cause of
coronavirus disease2019 (COVID-19), which has become a public health emergency of
international concern1. Angiotensin-converting enzyme2 (ACE2) is the cell-entry
receptor for severe acute respiratory syndrome coronavirus (SARS-CoV)2. Here we
infected transgenic mice that express human ACE2 (hereafter, hACE2mice) with
SARS-CoV-2 and studied the pathogenicity of the virus. We observed weight loss as
well as virus replication in the lungs of hACE2 mice infected with SARS-CoV-2. The
typical histopathology was interstitial pneumonia with inltration of considerable
numbers of macrophages and lymphocytes into the alveolar interstitium, and the
accumulation of macrophages in alveolar cavities. We obser ved viral antigens in
bronchial epithelial cells, macrophages and alveolar epithelia. These phenomena
were not found in wild-type mice infected with SARS-CoV-2. Notably, we have
conrmed the pathogenicity of SARS-CoV-2 in hACE2 mice. This mouse model of
SARS-CoV-2 infection will be valuable for evaluating antiviral therapeutic agents and
vaccines, as well as understanding the pathogenesis of COVID-19.
In late December 2019, cases of COVID-19—which is caused by
SARS-CoV-2—were identified and reported from Wuhan city (Hubei
province, China), where they were linked to a seafood market at
which exotic animals were also sold and consumed1,3. The number
of confirmed cases has since soared: as of 25 February 2020, almost
78,000cases and over 2,700deaths were reported in China4, and
imported cases from travellers from mainland China were reported
in several other countries. It is critical to establish the pathogenicity
and biology of the virus for prevention and treatment of the disease.
Because SARS-CoV-2 is highly homologous with SARS-CoV, human
ACE2—which is the entry receptor of SARS-CoV—was also considered to
have a high binding ability with the SARS-CoV-2 by molecular biological
analysis2,5. We therefore used transgenic hACE2 mice and wild-type mice
infected with the HB-01 strain of SARS-CoV-2 to study the pathogenic-
ity of the virus.
Specific-pathogen-free male and female wild-type (n=15) or hACE2
(n=19) mice of 6–11months of age were inoculated intranasally with
SARS-CoV-2 strain HB-01 at a dosage of 10
5
50% tissue culture infectious
dose (TCID50) per 50μl inoculum volume per mouse, after the mice were
intraperitoneally anaesthetized using 2.5% avertin; mock-treated hACE2
mice (n=15) were used as control. Clinical manifestations were recorded
from 13mice (3HB-01-infected wild-type mice; 3mock-treated hACE2
mice; and 7HB-01-infected hACE2 mice). We observed slight bristled
fur and weight loss only in the HB-01-infected hACE2 mice—and not the
HB-01-infected wild-type mice or mock-treated hACE2 mice—during
the 14days of observation; other clinical symptoms, such as an arched
back and decreased response of external stimuli, were not found in any
of the mice. Notably, the weight loss of HB-01-infected hACE2 mice was
up to 8% at 5days post-infection (dpi) (Fig.1a).
Next, we examined viral replication and pathological changes in three
mice per group at each time point; the primary organs—including heart,
liver, spleen, lung, kidney, brain, intestine and testis—were collected
periodically. As shown in Fig.1b, viral loads were detectable by quantita-
tive PCR with reverse transcription (RT–qPCR) at 1, 3, 5 and 7dpi in the
lungs of HB-01-infected hACE2 mice (but not in those of HB-01-infected
wild-type mice; data not shown), and viral RNA copies reached a peak
of 106.77 copies per ml at 3dpi. Viral RNA was also detectable at 1dpi in
the intestine of HB-01-infected hACE2 mice, which was not detected
in other tissues along the timeline (Fig.1b). Although viral loads were
detectable in the intestine, no virus in the intestine was isolated at
1dpi; we therefore speculate that the viral load detected was residual
input inoculum from the nasal mucosa transferred to the intestines by
https://doi.org/10.1038/s41586-020-2312-y
Received: 2 February 2020
Accepted: 24 April 2020
Published online: 7 May 2020
Check for updates
1Beijing Key Laboratory for Animal Models of Emerging and Remerging Infectious Diseases, Institute of Laboratory Animal Science, Chinese Academy of Medical Sciences, Beijing, China. 2NHC
Key Laboratory of Human Disease Comparative Medicine, Comparative Medicine Center, Peking Union Medical College, Beijing, China. 3MHC Key Laboratory of Biosafety, National Institute for
Viral Disease Control and Prevention, China CDC, Beijing, China. 4Institute of Pathogen Biology, Chinese Academy of Medical Sciences, Beijing, China. 5Institute of Medical Biology, Chinese
Academy of Medical Sciences, Beijing, China. 6These authors contributed equally: Linlin Bao, Wei Deng, Baoying Huang, Hong Gao, Jiangning Liu. e-mail: wugz@ivdc.chinacdc.cn;
qinchuan@pumc.edu.cn
Content courtesy of Springer Nature, terms of use apply. Rights reserved
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