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Immunoelectron microscopic study on interactions of noninfectious sendai virus and murine cells
Abstract:
The early interactions of LLC-MK2 cell-grown noninfectious Sendai virus and a murine cell line, P815 mastocytoma ascitic cells, were studied by electron microscopy, using the ferritin-conjugated antibody technique with anti-virus glycoprotein serum. For comparison, the interactions of egg-grown infectious Sendai virus with the same cells were also examined. When noninfectious virus was adsorbed to the cells in the cold, the cell membranes become partially invaginated at the site of contact of adsorbed virions, but ferritin-conjugated antibodies did not penetrate into the areas of envelope-cell membrane association. This pattern of virus attachment was similar to that of infectious virus attachment. Upon subsequent incubation at 37 degrees C, most of the adsorbed noninfectious virions were taken into cytoplasmic vesicles and then degraded, although a few virions remained attached to the cell membrane. No evidence of fusion of envelopes of noninfectious virions was obtained. On the other hand, envelopes of infectious virions fused with the cell membrane, and the transferred viral antigens diffused on the cell surfaces and then decreased in number.
Insights
Noninfectious Sendai virus binds to P815 cells but does not fuse, unlike infectious Sendai virus. Noninfectious virions are internalized and degraded, while infectious virions fuse and release antigens.
Area of Science:
- Virology
- Cell Biology
- Immunology
Background:
- Sendai virus interactions with host cells are crucial for understanding viral entry and pathogenesis.
- Distinguishing between infectious and noninfectious viral particle behavior is essential for studying viral mechanisms.
Purpose of the Study:
- To investigate and compare the early interactions of noninfectious and infectious Sendai virus with P815 mastocytoma cells.
- To elucidate the mechanisms of viral attachment, entry, and antigen presentation in relation to viral infectivity.
Main Methods:
- Electron microscopy was employed to visualize virus-cell interactions.
- The ferritin-conjugated antibody technique using anti-Sendai virus glycoprotein serum was utilized to detect viral antigens.
- Comparative analysis of noninfectious (LLC-MK2 cell-grown) and infectious (egg-grown) Sendai virus interactions with P815 cells at different temperatures.
Main Results:
- Noninfectious Sendai virus adsorbed to P815 cells, causing membrane invagination but no fusion or antibody penetration.
- Infectious Sendai virus envelopes fused with the cell membrane, releasing viral antigens that diffused and diminished on the cell surface.
- Noninfectious virions were primarily internalized into cytoplasmic vesicles and degraded, with minimal remaining cell membrane attachment.
Conclusions:
- Noninfectious Sendai virus exhibits attachment to host cells but lacks the fusion capability of infectious virions.
- The fate of noninfectious Sendai virus involves endocytosis and degradation, contrasting with the fusion-mediated entry of infectious virus.
- These findings highlight distinct cellular interaction pathways for infectious versus noninfectious viral particles.