Nowadays, the population is still struggling with a post-COVID19 syndrome known as long COVID, including a broad spectrum of neurological problems. There is an urgent need for a better understanding and exploration of the mechanisms of coronavirus neurotropism. For this purpose, the neurotropic strain of mouse hepatitis virus (MHV-JHM) originating from the beta-coronavirus genus, the same as severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has been used. The role of the cytoskeleton during virus replication in neurons in vitro was determined to understand the mechanisms of MHV-JHM neuroinfection. We have described for the first time the changes of actin filaments during MHV-JHM infection. We also observed productive replication of MHV-JHM in neurons during 168 h p.i. and syncytial cytopathic effect. We discovered that the MHV-JHM strain modulated neuronal cytoskeleton during infection, which were manifested by: (i) condensation of actin filaments in the cortical layer of the cytoplasm, (ii) formation of microtubule cisternae structures containing viral antigen targeting viral replication site (iii) formation of tunneling nanotubes used by MHV-JHM for intercellular transport. Additionally, we demonstrated that the use of cytoskeletal inhibitors have reduced virus replication in neurons, especially noscapine and nocodazole, the microtubule shortening factors.

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 mice Support Protocol 1: Histological evaluation Support Protocol 2: Liver enzyme measurement Support Protocol 3: Western blot analysis of aquaporin expression Support Protocol 4: mRNA measurement Support Protocol 5: Immunohistochemistry/immunofluorescence Support Protocol 6: Tissue water measurement.

The severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has infected millions of people worldwide. SARS-CoV-2 belongs to the Betacoronavirus genus, containing the mouse hepatitis virus (MHV), an extensively studied animal coronavirus. Since MHV and SARS-CoV-2 share the same genus, MHV could offer insights relative to SARS-CoV-2 studies. MHV-3 strain causes hepatitis and cellular injury, making MHV-3 infection one of the best models for this debilitating disease. Surrogate coronaviruses have been used for virus resistance and inactivation studies, and although real-life conditions using SARS-CoV-2 should be encouraged, their use needs to be balanced with safety and costs. MHV can be manipulated under BSL2 laboratory conditions, unlike SARS-CoV-2, making it a model for studying the virucidal effects on coronaviruses. In this study, we used the betacoronavirus MHV-3 as a model to investigate the virucidal activity of an air disinfection equipment named STR Solution®, an air sterilizer with patented technology. MHV-3 was dried on different surfaces and exposed at varying distances from the STR Solution® equipment and at different exposure times. The residual infectivity was evaluated using the endpoint method. There was not a significant reduction (mean p-value = 0.4) of the viral titer under STR Solution® exposition. STR Solution® caused a slight decrease of the infectious particles\' titer (> 1 log10) only under the following conditions: polypropylene at 3 m, for 1 and 3 h (1.2 log10 reduction TCID50) and Sus domesticus skin at 0.05 m, for 1 h (1.3 log10 reduction TCID50), and at 3 m for 1 h (1.2 log10 reduction TCID50). These and other studies confirm the usefulness of this model to evaluate virucidal activity.

Multiple sclerosis (MS) is a common inflammatory demyelinating disease of the central nervous system. Although the etiology of MS is unknown, genetics and environmental factors, such as infections, play a role. Viral infections of mice have been used as model systems to study this demyelinating disease of humans. Three viruses that have long been studied in this capacity are Theiler\'s murine encephalomyelitis virus, mouse hepatitis virus, and Semliki Forest virus. This review describes the viruses themselves, the infection process, the disease caused by infection and its accompanying pathology, and the model systems and their usefulness in studying MS.

Mouse hepatitis virus (MHV) belongs to the group II coronaviruses. The virus produces nine genes encoding 11 proteins that could be recognized as structural proteins and nonstructural proteins and are crucial for viral RNA synthesis. The nucleocapsid (N) protein, one of the structural proteins, interacts with the 30.4 kb virus genomic RNA to form the helical nucleocapsid and associates with the membrane glycoprotein via its C-terminus to stabilize virion assembly. Here, the expression and crystallization of the MHV nucleocapsid protein C-terminal domain are reported. The crystals diffracted to 2.20 A resolution and belonged to space group P422, with unit-cell parameters a = 66.6, c = 50.8 A. Assuming the presence of two molecules in the asymmetric unit, the solvent content is 43.0% (V(M) = 2.16 A(3) Da(-1)).

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Samples taken at different intervals of time from suspension cultures of the NCTC 1469 line of mouse liver-derived (ML) cells infected with a mouse hepatitis virus have been studied with the electron microscope. The experiments revealed that the viruses are incorporated into the cells by viropexis within 1 hour after being added to the culture. An increasing number of particles are found later inside dense cytoplasmic corpuscles similar to lysosomes. In the cytoplasm of the cells from the samples taken 7 hours after inoculation, two organized structures generally associated and never seen in the controls are observed: one consists of dense material arranged in a reticular disposition (reticular inclusion); the other is formed by small tubules organized in a complex pattern (tubular body). No evidence has been found concerning their origin. Their significance is discussed. With the progression of the infection a system of membrane-bounded tubules and cisternae is differentiated in the cytoplasm of the ML cells. In the lumen of these tubules or cisternae, which are occupied by a dense material, numerous virus particles are observed. The virus particles which originate in association with the limiting membranes of tubules and cisternae are released into their lumen by a \"budding\" process. The virus particles are 75 mmicro in diameter and possess a nucleoid constituted of dense particles or rods limiting an electron transparent core. The virus limiting membrane is sometimes covered by an outer layer of a dense material. In the cells from the samples taken 14 to 20 hours after inoculation, larger zones of the cell cytoplasm are occupied by inclusion bodies formed by channels or cisternae with their lumens containing numerous virus particles. In the samples taken 20 hours or more after the inoculation numerous cells show evident signs of degeneration.

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