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Theiler's murine encephalomyelitis virus group includes two distinct genetic subgroups that differ pathologically and
Abstract:
The intracellular development and RNA composition of Theiler's murine encephalomyelitis virus (TMEV) isolates were determined by electron microscopy, sucrose gradient centrifugation, and RNase T1 fingerprinting. Replication of FA virus, a virulent strain of TMEV, was characterized by the appearance of viral crystalline arrays in the cytoplasm of infected cells. In contrast, cells infected with the less virulent isolates (WW, TO4, BeAn 8386, and Yale) showed no crystalline arrays; instead, virions were found to be arranged between two layers of membranes in the cytoplasm of infected cells. Analysis of the RNAs of TMEV isolates showed that the RNAs were single-stranded molecules having sedimentation coefficients of 35S. RNase T1 fingerprinting of TMEV RNA revealed that striking differences between the virulent and less virulent TMEV isolates existed. Moreover, base composition analysis of RNase T1-resistant oligonucleotides of two TMEV isolates which represented the two subgroups indicated that there were no substantial oligonucleotides common to both subgroups. Based on these findings and the known difference in virulence, we suggest that the TMEV group contains two genetically district subgroups of viruses.
Insights
Theiler
Area of Science:
- Virology
- Molecular Biology
- Cell Biology
Background:
- Theiler's murine encephalomyelitis virus (TMEV) causes neurological disease.
- Understanding TMEV replication and genetic diversity is crucial for disease control.
Purpose of the Study:
- To investigate the intracellular development and RNA composition of TMEV isolates.
- To differentiate between virulent and less virulent TMEV strains based on molecular characteristics.
Main Methods:
- Electron microscopy to visualize viral structures within infected cells.
- Sucrose gradient centrifugation to analyze viral RNA sedimentation.
- RNase T1 fingerprinting to compare RNA sequences of different TMEV isolates.
Main Results:
- Virulent TMEV (FA strain) formed crystalline arrays in cytoplasm; less virulent strains did not.
- TMEV RNAs are single-stranded with a 35S sedimentation coefficient.
- Significant differences in RNA fingerprints and oligonucleotide composition were observed between virulent and less virulent TMEV subgroups.
Conclusions:
- TMEV isolates exhibit distinct intracellular replication patterns correlating with virulence.
- Genetic analysis of TMEV RNA reveals significant divergence between subgroups.
- These findings suggest TMEV comprises at least two genetically distinct subgroups.