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Entry and release of poliovirus as observed by electron microscopy of cultured cells
Abstract:
Cells of differing culture types were inoculated with poliovirus at 37 C, sampled at intervals during the replicative cycle, and examined in thin sections by electron microscopy. The earliest samples, taken at 2 and 5 min postinoculation, showed virus particles adjacent to the exterior of the plasma membrane and others that had apparently penetrated it directly; later samples showed fewer such particles or none. Particles lying in the peripheral cytoplasm frequently appeared swollen and distorted in shape. No sign of virus entry by a pinocytotic process was found at any time. At 3 hr, and subsequently during the replication cycle, particles of progeny virus appeared in the cytoplasm. They were found free in the cytoplasmic matrix, aligned along the elements of filamentous complexes, and enclosed within vesicles. Some of the vesicles were found to be open to the extracellular space, indicating a likely mechanism of virus release.
Insights
Poliovirus enters cells directly through the plasma membrane, not via pinocytosis. Progeny virus is released from cells through vesicles opening to the extracellular space.
Area of Science:
- Cell biology
- Virology
- Microscopy
Background:
- Poliovirus is a significant human pathogen.
- Understanding viral entry and release mechanisms is crucial for developing antiviral strategies.
Purpose of the Study:
- To investigate the entry and release mechanisms of poliovirus in cultured cells using electron microscopy.
Main Methods:
- Cells were inoculated with poliovirus and sampled at various time points.
- Thin sections of cells were examined using electron microscopy.
Main Results:
- Poliovirus particles were observed directly penetrating the plasma membrane.
- No evidence of pinocytotic entry was found.
- Progeny virus particles appeared in the cytoplasm and were released via vesicles.
Conclusions:
- Poliovirus entry occurs through direct plasma membrane penetration.
- Vesicular release is a likely mechanism for poliovirus egress.