Mouse Hepatitis Virus (MHV) – NAVLE Study Guide

Overview and Clinical Importance

Mouse Hepatitis Virus (MHV) is a highly contagious coronavirus that is one of the most common infectious agents in laboratory mouse colonies worldwide. MHV causes a spectrum of diseases ranging from asymptomatic infection to severe hepatic necrosis, enteritis, encephalitis, and respiratory disease, depending on viral strain, mouse age, immune status, and genetics.

MHV is critical for the NAVLE because it represents the prototype murine coronavirus, shares genomic features with SARS-CoV-2, and is a major confounding variable in research. Understanding MHV strain differences and disease manifestations is essential.

Etiology and Viral Characteristics

Viral Classification

• Family: Coronaviridae
• Genus: Betacoronavirus
• Genome: Positive-sense single-stranded RNA (27-32 kb)
• Morphology: Enveloped, spherical, 80-120 nm, crown-like surface spikes
• Strains: Over 25 strains (MHV-1, MHV-3, MHV-A59, MHV-JHM, MHV-Y, etc.)

MHV Strain Classification by Tropism

Epidemiology and Transmission

• Fecal-Oral (Primary): Enterotropic strains shed in feces
• Aerosol/Respiratory: Polytropic strains shed in respiratory secretions
• Fomites: Contaminated bedding, cages, equipment; virus survives days
• Asymptomatic Carriers: Immune adults shed virus without clinical signs

Clinical Presentation by Disease Form

IMPORTANT: Most MHV infections in immunocompetent adult mice are SUBCLINICAL. Disease expression depends on strain, age, genetics, and immune status.