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Electron-microscopic morphology of virus replication in cells of the murine Borstel-leukemia X 429
Abstract:
Intraperitoneal injections of cell-free filtrates of Borstel-leukemia X 429 (immature-cell myeloid leukemia induced by 200 rad whole-body X-irradiation) were given to 330 1-week-old NMRI mice of both sexes. Leukemia developed in 21% after injection of cell-free filtrates from leukemic spleens and in 20% after injection of cell-free filtrates from leukemic lymph nodes. The mean time lapse from injection to the appearance of the leukemia was 12.8 months. The virus replication in the newly formed leukemic cells, was studied by electron microscopy. Special attention was given to the relation between A-particles and mature type-C viruses. The leukemia cells contain intracytoplasmic and intracisternal A-particles consisting of two concentric spherical shells with an external diameter of 70 nm. A-particles present mainly as closed "virus fields" in the vicinity of the cell nucleus, frequently in the Golgi area. The intracisternal A-particles appear inside the lumen of expanded vesicles of the cytoplasma. Typ-C viruses develop on the cytoplasmic membrane and/or on the outer cell membrane by condensation of crescent-shaped electron-dense zones. All layers of the later mature virus are recognisable in these early morphological stages. After the virus has been detached from the cell it collapses, and the outer membrane appears wrinkled. No spatial correlation between the storage sites of the A-particles and the sites of formation of mature type-C viruses are demonstrable.
Insights
Cell-free filtrates from Borstel-leukemia induced leukemia in mice. Electron microscopy revealed A-particles and type-C viruses in leukemic cells, but no direct spatial correlation was found between them.
Area of Science:
- Virology
- Oncology
- Cell Biology
Background:
- Borstel-leukemia X 429 is an immature-cell myeloid leukemia induced by X-irradiation.
- Leukemia induction via cell-free filtrates suggests a viral etiology.
- Understanding virus replication in leukemia is crucial for disease mechanisms.
Purpose of the Study:
- To investigate the viral etiology of Borstel-leukemia X 429.
- To study virus replication in induced leukemic cells using electron microscopy.
- To determine the relationship between A-particles and type-C viruses in leukemia.
Main Methods:
- Intraperitoneal injection of cell-free filtrates from leukemic spleens and lymph nodes into young NMRI mice.
- Induction and observation of leukemia development over time.
- Ultrastructural analysis of leukemic cells using electron microscopy to visualize viral particles.
Main Results:
- Leukemia developed in 20-21% of mice injected with cell-free filtrates.
- Mean latency period for leukemia development was 12.8 months.
- Intracytoplasmic and intracisternal A-particles and mature type-C viruses were observed in leukemic cells, with type-C virus budding from cell membranes.
Conclusions:
- Cell-free filtrates of Borstel-leukemia can induce leukemia in mice, supporting a viral cause.
- A-particles and type-C viruses are present in leukemic cells, but their formation sites show no spatial correlation.
- Further research is needed to elucidate the precise role and interaction of these viral particles in leukemia pathogenesis.