Electron-microscopic appearance of the DA virus, a demyelinating murine virus
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Abstract:
The DA virus is a neurotropic murine virus which can induce acute encephalomyelitis in suckling mice and a chronic myelopathy in weanlings. The agent has been attenuated by serial passage in baby hamster kidney (BHK-21) cells. When attenuated virus is inoculated in 8-week-old C3HeJ mice a myelopathy of delayed onset with prominent demyelination of lateral and anterior columns occurs. The DA virus is believed to be related to the Theiler murine encephalomyelitis (TME) viruses because of the similar clinical and pathological conditions which it causes, and because neutralization tests indicate shared antigens between it and GD7, a TME virus. This paper reports electron-microscopic studies of BHK-21 cells infected with DA virus. The cells were prepared 24 and 48 hr after inoculation. Cytopathic effects were observed and infected cells contained plaques consisting of numerous 25 nm virus particles in crystalline array. The virions were exclusively intracytoplasmic and were morphologically indistinguishable from human poliomyelitis virus. These observations appear to establish DA as a picorna virus, related to the TME virus group. The chronic myelopathy caused by DA may prove relevant to chronic demyelinative myelopathies in man, such as multiple sclerosis, and also to amyotrophic lateral sclerosis.
Insights
The DA virus, a neurotropic murine pathogen, causes myelopathy in mice. Electron microscopy reveals it is a picornavirus, potentially offering insights into human demyelinative diseases like multiple sclerosis.
Area of Science:
- Virology
- Neuroscience
- Pathology
Background:
- The DA virus is a neurotropic murine virus causing encephalomyelitis and chronic myelopathy.
- It shares characteristics with Theiler murine encephalomyelitis (TME) viruses, including similar pathology and antigenic properties.
- Previous studies suggest a relationship between DA virus and TME viruses.
Purpose of the Study:
- To investigate the ultrastructural morphology of baby hamster kidney (BHK-21) cells infected with the DA virus.
- To characterize the DA virus based on its morphology and cellular effects.
- To explore the potential relevance of DA virus-induced myelopathy to human neurological conditions.
Main Methods:
- Infection of BHK-21 cells with the DA virus.
- Electron microscopy examination of infected cells at 24 and 48 hours post-inoculation.
- Analysis of virion morphology, arrangement, and cellular localization.
Main Results:
- Cytopathic effects were observed in infected BHK-21 cells.
- Virus particles, approximately 25 nm in diameter, were found in crystalline arrays within the cytoplasm.
- The virions were morphologically identical to human poliovirus, indicating DA virus is a picornavirus.
Conclusions:
- The DA virus is identified as a picornavirus based on electron microscopic evidence.
- The DA virus is antigenically related to the TME virus group.
- The chronic myelopathy induced by the DA virus may serve as a relevant model for studying human demyelinative diseases such as multiple sclerosis and amyotrophic lateral sclerosis.