Virus-induced central positional nystagmus in mice

Area of Science:

• Neuroscience
• Virology
• Immunology

Background:

• Mouse hepatitis virus (MHV) is a significant pathogen affecting murid rodents.
• Neurological complications can arise from MHV infections, impacting the central nervous system (CNS).
• Understanding the long-term effects of MHV on neurological function is crucial for disease management.

Purpose of the Study:

• To investigate the neurological manifestations of a temperature-sensitive MHV mutant in young mice.
• To characterize the development and duration of geotropic direction-changing nystagmus following MHV infection.
• To correlate clinical signs with histopathological findings, specifically demyelination in the CNS.

Main Methods:

• Intracerebral injection of a temperature-sensitive MHV mutant into 4-week-old BALB/c mice.
• Observation and recording of geotropic direction-changing nystagmus in lateral body positions.
• Evaluation of semicircular canal nystagmic responses before and after infection.
• Clinical assessment for signs of weakness, ataxia, and tremor.
• Histopathological examination of the CNS to identify demyelination.

Main Results:

• Geotropic direction-changing nystagmus was observed in infected mice starting 2 days post-infection.
• The nystagmus persisted for at least six months.
• Semicircular canal responses remained unaltered, suggesting the vestibular system was not directly affected.
• Clinical signs included general weakness, ataxia, and tremor.
• Histopathology revealed demyelination in various CNS regions 2 weeks after infection.

Conclusions:

• Temperature-sensitive MHV infection in young mice induces persistent geotropic direction-changing nystagmus.
• The observed nystagmus is likely a consequence of CNS demyelination rather than direct semicircular canal dysfunction.
• This study highlights the long-term neurological sequelae of MHV infection in a murine model.