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Demyelination in mice after two or three infections with avirulent Semliki Forest virus
Abstract:
Adult mice given two or three intraperitoneal inoculations with avirulent Semliki Forest Virus showed typical lesions of a viral encephalitis similar to those caused by a virulent strain of the virus. Demyelination also was seen in the medulla and in the folia of the cerebellar white matter. Neuronophagia was seen only in mice that had had three successive infections. The repeated inoculations of avirulent virus exacerbates the encephalitis of a single inoculation and causes demyelination. The mice did not have neurological clinical signs except for a short-lived weakness of the hind legs. No central nervous system lesions were seen by the 7th and 8th week after the initial infection and all mice recovered.
Insights
Repeated inoculations with avirulent Semliki Forest Virus in adult mice caused viral encephalitis and demyelination. While mice showed transient hind leg weakness, all recovered without lasting central nervous system damage.
Area of Science:
- Neuroscience
- Virology
- Immunology
Background:
- Semliki Forest Virus (SFV) can cause encephalitis.
- The effects of repeated avirulent SFV infections on the central nervous system (CNS) are not fully understood.
Purpose of the Study:
- To investigate the impact of repeated intraperitoneal inoculations of avirulent Semliki Forest Virus (SFV) on adult mice.
- To characterize the resulting neuropathological changes and clinical signs.
Main Methods:
- Adult mice were inoculated intraperitoneally with two or three doses of avirulent SFV.
- Mice were monitored for clinical signs and neuropathological lesions in the CNS.
Main Results:
- Intraperitoneal inoculations with avirulent SFV induced viral encephalitis and demyelination in the medulla and cerebellum.
- Neuronophagia was observed only in mice receiving three successive infections.
- Clinical signs were limited to transient hind leg weakness, with no persistent CNS lesions observed by weeks 7-8 post-infection.
Conclusions:
- Repeated administration of avirulent SFV exacerbates encephalitis and causes demyelination.
- Despite neuropathological changes, adult mice demonstrate a capacity for recovery from these induced CNS insults.