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Giant cell formation in the brain of suckling mice infected with mouse hepatitis virus, JHM strain
Abstract:
After intranasal inoculation with a neurotropic mouse hepatitis virus, JHM strain, suckling mice less than 2 weeks of age died in 4 or 5 days postinoculation, while those 3 weeks or more of age survived. In the brain lesions of mice 8 days or less of age, there appeared two different types of multinucleated giant cells. One of them which was irregular in shape with many virus particles, appeared mostly in the subependymal or perivascular areas after 72 h postinoculation and it seemed to have resulted from a fusion of two or more infected macrophages. The other type of giant cells which was oval in shape with a small number of virus particles, appeared within degenerative lesions at 96 h postinoculation. It consisted of two morphologically different parts and seemed to be a complex of infected neurons and reacting macrophages. In the cerebral lesions of mice 2 to 4 weeks of age, only the former type of giant cells appeared.
Insights
Young mice infected with mouse hepatitis virus (MHV) develop distinct giant cells in the brain. Older mice survive, while younger mice show age-dependent mortality and specific cellular responses.
Area of Science:
- Virology
- Neuroscience
- Immunology
Background:
- Neurotropic mouse hepatitis virus (MHV), JHM strain, causes severe disease in suckling mice.
- Age-dependent susceptibility to MHV infection is a critical factor in disease outcome.
Purpose of the Study:
- To investigate the neuropathogenesis of MHV infection in mice of different age groups.
- To characterize the types and origins of multinucleated giant cells in MHV-induced brain lesions.
Main Methods:
- Intranasal inoculation of mice with MHV (JHM strain).
- Histopathological examination of brain lesions at various time points postinoculation.
- Electron microscopy to identify virus particles and cellular structures.
Main Results:
- Mice less than 2 weeks old died within 4-5 days, while older mice survived.
- Two distinct types of multinucleated giant cells were observed in the brains of young mice.
- Type 1 giant cells (irregular, macrophage-derived) appeared early in subependymal/perivascular areas.
- Type 2 giant cells (oval, neuron-macrophage complex) appeared later within degenerative lesions.
- Older mice (2-4 weeks) only exhibited Type 1 giant cells.
Conclusions:
- MHV infection elicits distinct age-dependent neuropathological responses in mice.
- Multinucleated giant cells, particularly macrophage-derived ones, are key features of MHV encephalitis.
- The cellular composition of giant cells may reflect different stages or mechanisms of viral pathogenesis.