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Updated: Nov 7, 2025
Live Imaging and Quantification of Viral Infection in K18 hACE2 Transgenic Mice Using Reporter-Expressing Recombinant SARS-CoV-2
Published on: November 5, 2021
A novel pseudovirus-based mouse model of SARS-CoV-2 infection to test COVID-19 interventions
Ssu-Hsueh Tseng1, Brandon Lam1,2, Yu Jui Kung1
1Department of Pathology, Johns Hopkins School of Medicine, Baltimore, MD, USA.
Background:
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.
Methods:
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.
Results:
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.
Conclusions:
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.
Insights
A new preclinical mouse model effectively simulates SARS-CoV-2 (Coronavirus Disease 2019) infection using pseudovirus. This model allows for testing of COVID-19 interventions and future coronavirus preparedness.
Area of Science:
- Virology
- Immunology
- Preclinical Research
Background:
- The COVID-19 pandemic highlights the need for effective preclinical models to study SARS-CoV-2 infection.
- Existing mouse models are limited due to differences in ACE2 receptor expression and virus safety concerns.
- Developing a safe and relevant animal model is crucial for understanding viral pathogenesis and testing therapeutics.
Purpose of the Study:
- To develop a novel preclinical animal model for SARS-CoV-2 infection.
- To utilize non-infectious SARS-CoV-2 pseudovirus (PsV) for safe in vivo studies.
- To establish a system for evaluating potential interventions against SARS-CoV-2.
Main Methods:
- Generated SARS-CoV-2 pseudovirus (PsV) using a lentivirus system with SARS-CoV-2 spike proteins.
- Administered intranasally human ACE2 (hACE2) to mice to facilitate viral entry.
- Challenged mice with SARS-CoV-2 PsV, including variants with different ACE2 binding properties.
- Utilized recombinant receptor-binding domain (RBD) protein to demonstrate in vitro and in vivo control of infection.
Main Results:
- Demonstrated successful infection of the mouse respiratory tract with SARS-CoV-2 PsV after intranasal hACE2 transduction.
- Showcased the ability to manipulate the model using RBD protein to block PsV infection both in vitro and in vivo.
- Validated the infectivity of PsVs carrying spike protein variants with varying ACE2 binding affinities.
Conclusions:
- The developed SARS-CoV-2 PsV system provides a viable preclinical mouse model for studying viral infections.
- This model is suitable for testing the efficacy of interventions and preventative treatments for COVID-19.
- The system's adaptability to different mouse strains and coronaviruses makes it valuable for current pandemic response and future outbreak preparedness.
