A Mouse Model of MHV‐1 Virus Infection for Study of Acute and Long COVID Infection

Abstract

COVID‐19, caused by SARS‐CoV‐2, has had a significant global impact. While vaccines and treatments have reduced severe cases and deaths, the long‐term effects are not yet well understood. Current models used for research, such as non‐human primates and transgenic mice, are expensive and require scarce Biosafety Level‐3 (BSL‐3) laboratories, thereby limiting their practicality. However, the mouse hepatitis virus 1 (MHV‐1) mouse model offers a promising alternative. This surrogate model can be investigated in more widely available Biosafety Level‐2 (BSL‐2) laboratories. Furthermore, mice are affordable and easy to handle, and utilizing MHV‐1 as a surrogate for SARS‐CoV‐2 eliminates the need for costly transgenic mice. Importantly, the MHV‐1 model successfully recapitulates COVID‐19‐related clinical symptoms, weight loss, multiorgan pathological changes and failure in acute stages, irreversible neurological complications, and other long‐term organ dysfunction post‐infection, which are similar to available human data post‐COVID‐19. To assist researchers in establishing and using the MHV‐1 mouse model, this protocol offers comprehensive guidance encompassing procedures for animal preparation, induction of viral infection, clinical observation, pathological changes, and tissue analysis for mechanistic studies, thereby yielding valuable insights into disease mechanisms and progression. By adopting the MHV‐1 model and the provided protocols, researchers can effectively circumvent financial constraints and the limited availability of BSL‐3 laboratories, thus facilitating a more accessible and cost‐effective approach to investigating the underlying mechanisms of SARS‐CoV‐2 pathophysiology and exploring potential therapeutic interventions. © 2023 Wiley Periodicals LLC.Basic Protocol: Induction of mouse hepatitis virus 1 (MHV‐1) infection in A/J miceSupport Protocol 1: Histological evaluationSupport Protocol 2: Liver enzyme measurementSupport Protocol 3: Western blot analysis of aquaporin expressionSupport Protocol 4: mRNA measurementSupport Protocol 5: Immunohistochemistry/immunofluorescenceSupport Protocol 6: Tissue water measurement

Dermatologic Changes in Experimental Model of Long COVID

“…Mice were split into (1) a healthy control group, (2) an MHV-1 virus-inoculated group, and (3) an MHV-1 virus-inoculated group that was treated with SPK. MHV-1 viral inoculation was performed as previously described [ 14 , 15 , 16 , 18 ]. Briefly, groups 2 and 3 were inoculated intranasally with 5000 PFU MHV-1 and were observed to ensure adequate inhalation of the virus.…”

“…This syndrome is distinguished by a markedly high mortality rate [ 8 , 9 , 10 , 11 , 12 , 13 ]. These mice exhibit pronounced lung injury with mortality rates ranging from 40% to 60% between days 7 and 12 post-infection [ 14 ]. Upon examination at the time of death, the lungs display severe interstitial pneumonitis characterized by interstitial inflammatory reactions, along with substantial infiltrations of lymphocytes and macrophages [ 15 , 16 , 17 , 18 ].…”

“…Given the common genus shared by MHV severe acute respiratory syndrome coronavirus and SARS-CoV-2, insights gleaned from MHV-1 could potentially provide a mechanistic understanding of SARS-CoV-2 infection in humans [ 14 ]. While there are notable similarities between MHV-1 in mice and SARS-CoV-2 in humans, such as certain pathogenic features, differences exist (e.g., there are variations in viral binding receptors angiotensin-converting enzyme-2 (ACE2) in SARS-CoV-2 versus carcinoembryonic antigen-related cell adhesion molecule 1 (CEACAM1) in MHV-1) [ 15 , 16 , 18 , 29 ].…”

Neuropsychiatric sequelae in an experimental model of post-COVID syndrome in mice

“…Therefore, this model was characterized by mild lung disease with mild systemic alterations and viral dissemination, constituting a suitable platform to study sequelae post-coronavirus infection. Importantly, infection with MHV-1, another murine betacoronavirus, was recently shown to recapitulate some aspects of PCS in mice (Masciarella et al, 2023).…”

A Murine Model of Post-acute Neurological Sequelae Following SARS-CoV-2 Variant Infection

“…Another study reported increased reactive astrocytes and microglia, hyperphosphorylated TDP-43 and tau, and decrease in synaptic protein synaptophysin-1 and defective neuronal integrity in A/J mice 12 months post-infection. Although the study recapitulates long-term sequelae of COVID-19, a mouse hepatitis virus 1 (MHV-1) was used in this study 48,49 .…”