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Mouse thymic virus infection: ultrastructural and immunocytochemical studies of infected thymus cells
1Centre de Recherche en Virologie, Institut Armand-Frappier, Laval, Quebec, Canada.
Abstract:
Only limited attention has been paid to the cell population that is affected in the course of Mouse Thymic Virus (MTV) infection. In the present study, thymic cells of newborn mice infected with MTV were examined for general ultrastructural and immunocytochemical characteristics. The earliest sign of infection was detected 5 days after inoculation. Lymphocytes, epithelial reticular cells, macrophages, and lymphoepithelial cell complexes (thymic nurse cells) were affected. Viral particles and filamentous structures were present in both the nucleus and the cytoplasm of these cells. At more advanced stages of cellular necrosis, 6 to 7 days post-infection, cytoplasmic granulation and loss in definition of cytoplasmic organelles became apparent. This was followed by nuclear degradation and cellular aggregation. The selective effect of MTV on lymphocyte subpopulations was also observed. Two populations of infected lymphocytes were identified by single and double immunogold labelling employing monoclonal antibodies and different sizes of gold particles. CD4+8+ and CD4+8- lymphocytes were found to be selectively lysed by MTV.
Insights
Mouse Thymic Virus (MTV) infects various thymic cells in newborn mice, including lymphocytes. MTV selectively targets and lyses CD4+8+ and CD4+8- lymphocytes, impacting immune cell development.
Area of Science:
- Immunology
- Virology
- Cell Biology
Background:
- Limited research exists on the specific cell populations affected by Mouse Thymic Virus (MTV).
- Understanding MTV's cellular targets is crucial for comprehending its pathogenesis in the thymus.
Purpose of the Study:
- To investigate the ultrastructural and immunocytochemical characteristics of thymic cells during MTV infection.
- To identify the specific lymphocyte subpopulations targeted and lysed by MTV.
Main Methods:
- Infection of newborn mice with MTV.
- Examination of thymic cells using electron microscopy for ultrastructural changes.
- Immunocytochemical analysis with monoclonal antibodies and immunogold labeling to identify infected cell types and lymphocyte subpopulations.
Main Results:
- MTV infection was detectable by day 5 post-inoculation.
- Infected cells included lymphocytes, epithelial reticular cells, macrophages, and thymic nurse cells, showing viral particles in nucleus and cytoplasm.
- Advanced stages (6-7 days) exhibited cellular necrosis, cytoplasmic granulation, organelle degradation, nuclear breakdown, and cellular aggregation.
- MTV selectively lysed CD4+8+ and CD4+8- lymphocytes.
Conclusions:
- MTV affects multiple thymic cell types, leading to significant cellular damage and necrosis.
- MTV demonstrates a selective tropism for specific T-lymphocyte subsets (CD4+8+ and CD4+8-), indicating a targeted immune evasion or destruction mechanism.