Theiler's murine encephalomyelitis virus in nonbarrier rat colonies
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Updated: Aug 15, 2026
A Model for Epilepsy of Infectious Etiology using Theiler's Murine Encephalomyelitis Virus
Published on: June 23, 2022
Daniele Masselli Rodrigues1, Sandra Soares Martins, Rovilson Gilioli
1Multidisciplinary Center for Biological Investigation, Institute of Biology, State University of Campinas, São Paulo, Brazil.
Abstract:
Theiler's murine encephalomyelitis virus (TMEV), a member of the genus Cardiovirus, is an enteric pathogen of mice that causes acute encephalomyelitis followed by persistent central nervous system infection with chronic inflammation and demyelination after intracerebral inoculation. Although TMEV is a mouse pathogen, antibodies against TMEV strain GDVII have been detected in conventional rat colonies. Natural infection of rats by Cardiovirus has not yet been described. The purpose of this study was to demonstrate TMEV infection of rat colonies by using serologic assays, reverse transcription-polymerase chain reaction (RT-PCR) analysis, and clinical characterization. Indirect immunofluorescence assay of rat serum samples demonstrated antibodies against TMEV-GDVII in 86.3% of samples analyzed, and 77.2% of the antibody-positive samples had neutralizing antibodies. To determine whether rats can be infected experimentally with TMEV-GDVII, specific pathogen-free newborn mice and rats were inoculated intracerebrally with intestinal suspensions from seropositive rats. Both species showed the typical clinical signs of TMEV infection in mice, which is characterized by flaccid hindlimb paralysis and tremor. RT-PCR in brain tissue of experimentally infected animals detected RNA sequences corresponding to the 5' noncoding region of Cardiovirus known as the 'internal ribosome entry site.' These results suggest that rats can be naturally infected with TMEV and related Cardiovirus. Therefore, continued health monitoring for TMEV infection should be included in rat colonies mainly because these animals are used for various experimental purposes.
Insights
Rats may be naturally infected with Theiler's murine encephalomyelitis virus (TMEV), a Cardiovirus. This study detected TMEV antibodies and RNA in rats, suggesting natural infection and the need for health monitoring in research colonies.
Area of Science:
- Virology
- Immunology
- Neurology
Background:
- Theiler's murine encephalomyelitis virus (TMEV) is a mouse enteric pathogen causing central nervous system disease.
- Antibodies to TMEV strain GDVII have been found in rats, but natural Cardiovirus infection in rats is undescribed.
Purpose of the Study:
- To investigate and demonstrate natural TMEV infection in rat colonies.
- To confirm TMEV infectivity in rats through serologic, molecular, and clinical analyses.
Main Methods:
- Serologic assays (indirect immunofluorescence) to detect TMEV-GDVII antibodies in rat sera.
- Experimental inoculation of specific pathogen-free mice and rats with TMEV-GDVII.
- Reverse transcription-polymerase chain reaction (RT-PCR) to detect Cardiovirus RNA in brain tissue.
Main Results:
- 86.3% of rat serum samples showed antibodies against TMEV-GDVII, with 77.2% having neutralizing antibodies.
- Experimentally infected rats and mice exhibited clinical signs of TMEV infection, including paralysis and tremor.
- RT-PCR confirmed the presence of Cardiovirus RNA in the brain tissue of infected animals.
Conclusions:
- Results strongly suggest that rats can be naturally infected with TMEV and related Cardiovirus.
- Ongoing health monitoring for TMEV is recommended for rat colonies due to their use in research.
