Postinflammatory remyelination in the spinal cord of mice infected with mouse hepatitis virus, JHM strain
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K Takahashi1, N Goto, Y Matsubara
1Department of Veterinary Pathology, Faculty of Agriculture, University of Tokyo, Japan.
Abstract:
The spinal cords in mice surviving acute infection for 30 days following lumbar inoculation with mouse hepatitis virus, JHM strain, were examined for virus growth and pathologic changes by light and electron microscopy. Virus titer reached a maximum level on day 6 postinoculation (p.i.) and became negative on day 10 p.i. On days 5 to 10 p.i. there were severe disruption of myelin sheath and marked phagocytosis of myelin by macrophages. Viral particles were seen in degenerating glial cells. On days 15 to 20 p.i. proliferation of oligodendrocytes was noticed in association with thinly myelinated axons with decreased number of macrophages. On days 25 to 30 p.i. affected axons were mostly remyelinated by oligodendrocytes and the interaxonal space was packed with the processes of fibrous astrocytes containing myelin debris and lipid droplets. In the subpial areas of more widespread lesions some axons were remyelinated by Schwann cells.
Insights
Mouse hepatitis virus (MHV) JHM strain causes acute spinal cord infection in mice. Myelin damage and repair were observed, with remyelination occurring by day 25 post-infection.
Area of Science:
- Neurovirology
- Pathology
- Immunology
Background:
- Mouse hepatitis virus (MHV), strain JHM, is a neurotropic coronavirus.
- Acute viral infections can cause significant central nervous system pathology.
Purpose of the Study:
- To investigate the temporal dynamics of virus replication and neuropathology in mouse spinal cords following JHMV infection.
- To characterize the cellular and molecular events during myelin damage and repair.
Main Methods:
- Light and electron microscopy were used to examine spinal cord tissues.
- Virus titers were measured at various time points post-inoculation.
Main Results:
- Viral load peaked at day 6 post-inoculation (p.i.) and became undetectable by day 10 p.i.
- Severe myelin sheath disruption and phagocytosis by macrophages occurred between days 5-10 p.i.
- Oligodendrocyte proliferation and remyelination were observed from day 15 p.i., with significant remyelination by day 25 p.i.
Conclusions:
- The study details the sequential pathological changes and recovery processes in the spinal cord after JHMV infection.
- Evidence of both oligodendrocyte- and Schwann cell-mediated remyelination was observed.