Mice with induced pulmonary morbidities display severe lung inflammation and mortality following exposure to SARS-CoV-2
Reut Falach, Liat Bar-On, Shlomi Lazar, Tamar Kadar, Ohad Mazor, Moshe Aftalion, David Gur, Yentl Evgy, Ohad Shifman, Tamar Aminov, Ofir Israeli, Inbar Cohen-Gihon, Galia Zaide, Hila Gutman, Yaron Vagima, Efi Makdasi, Dana Stein, Ronit Rosenfeld, Ron Alcalay, Eran Zahavy, Haim Levy, Itai Glinert, Amir Ben-Shmuel, Tomer Israely, Sharon Melamed, Boaz Politi, Hagit Achdout, Shmuel Yitzhaki, Chanoch Kronman, Tamar Sabo
Reut Falach, Liat Bar-On, Shlomi Lazar, Tamar Kadar, Ohad Mazor, Moshe Aftalion, David Gur, Yentl Evgy, Ohad Shifman, Tamar Aminov, Ofir Israeli, Inbar Cohen-Gihon, Galia Zaide, Hila Gutman, Yaron Vagima, Efi Makdasi, Dana Stein, Ronit Rosenfeld, Ron Alcalay, Eran Zahavy, Haim Levy, Itai Glinert, Amir Ben-Shmuel, Tomer Israely, Sharon Melamed, Boaz Politi, Hagit Achdout, Shmuel Yitzhaki, Chanoch Kronman, Tamar Sabo
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Research Article COVID-19

Mice with induced pulmonary morbidities display severe lung inflammation and mortality following exposure to SARS-CoV-2

Abstract

Mice are normally unaffected by SARS coronavirus 2 (SARS-CoV-2) infection since the virus does not bind effectively to the murine version of the angiotensin-converting enzyme 2 (ACE2) receptor molecule. Here, we report that induced mild pulmonary morbidities rendered SARS-CoV-2–refractive CD-1 mice susceptible to this virus. Specifically, SARS-CoV-2 infection after application of low doses of the acute lung injury stimulants bleomycin or ricin caused severe disease in CD-1 mice, manifested by sustained body weight loss and mortality rates greater than 50%. Further studies revealed markedly higher levels of viral RNA in the lungs, heart, and serum of low-dose ricin–pretreated mice compared with non-pretreated mice. Furthermore, lung extracts prepared 2–3 days after viral infection contained subgenomic mRNA and virus particles capable of replication only when derived from the pretreated mice. The deleterious effects of SARS-CoV-2 infection were effectively alleviated by passive transfer of polyclonal or monoclonal antibodies generated against the SARS-CoV-2 receptor binding domain (RBD). Thus, viral cell entry in the sensitized mice seems to depend on viral RBD binding, albeit by a mechanism other than the canonical ACE2-mediated uptake route. This unique mode of viral entry, observed over a mildly injured tissue background, may contribute to the exacerbation of coronavirus disease 2019 (COVID-19) pathologies in patients with preexisting morbidities.

Authors

Reut Falach, Liat Bar-On, Shlomi Lazar, Tamar Kadar, Ohad Mazor, Moshe Aftalion, David Gur, Yentl Evgy, Ohad Shifman, Tamar Aminov, Ofir Israeli, Inbar Cohen-Gihon, Galia Zaide, Hila Gutman, Yaron Vagima, Efi Makdasi, Dana Stein, Ronit Rosenfeld, Ron Alcalay, Eran Zahavy, Haim Levy, Itai Glinert, Amir Ben-Shmuel, Tomer Israely, Sharon Melamed, Boaz Politi, Hagit Achdout, Shmuel Yitzhaki, Chanoch Kronman, Tamar Sabo

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Figure 7

Expression of ACE2 and TMPRSS2 and RBD binding in lung cells of LDR mice.

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Expression of ACE2 and TMPRSS2 and RBD binding in lung cells of LDR mice...
(A and B) Flow cytometry analysis of lung cells harvested from LDR (filled bars) and sham-treated (empty bars) mice 2 days after treatment. ACE2 (A, n = 3), TMPRSS2 (B, n = 6). Data referring to percentage of positive cells out of the indicated cell types are presented as mean ± SEM, analyzed using 2-way ANOVA followed by Bonferroni’s posttests, **P < 0.01. (C and D) Confocal microscopy scans of lung sections. (C) Sections from LDR (2 days after LDR administration) and naive mice were incubated with RBD-huFc or AChE-huFc (Fc control) and then immunostained with anti-human AF594. Staining of RBD in red and identification of nuclei by DAPI in blue. Scale bar: 50 μm. (D) Scatterplots of the fluorescence staining intensities of RBD expressed as MFI ± SEM. n = 4 mice, 5 scanned fields/lung, analyzed using unpaired t test, ***P < 0.001.