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Penetration of host cell membranes by adenovirus 2
Abstract:
Highly purified human adenovirus type 2 directly penetrated the plasma membranes of KB cells. The process of membrane penetration resulted in the appearance of large numbers of adenovirions free in the cytoplasm of the infected cells. The virions underwent a morphological change as they penetrated the cell surface. Penetration of the plasma membranes and the accompanying alteration in virion morphology was dependent on a function associated with the intact cells, because neither event occurred when purified virions were added to isolated cell membranes. Inactivation of the adenovirions with heat or antibodies before inoculation of the cells reduced the infectivity of the virus population and prevented the appearance of virions free in the cytoplasm. The inactivation of the virions did not significantly reduce the number of virus particles which were found in cell vacuoles and pinocytotic vesicles.
Insights
Human adenovirus type 2 penetrates cell membranes directly, releasing virions into the cytoplasm. This entry mechanism requires intact cells and causes virion shape changes, unlike vacuolar uptake.
Area of Science:
- Virology
- Cell Biology
- Molecular Biology
Background:
- Human adenovirus type 2 is a significant human pathogen.
- Understanding virus-cell interactions is crucial for developing antiviral strategies.
Purpose of the Study:
- To investigate the entry mechanism of human adenovirus type 2 into host cells.
- To elucidate the role of intact cells in adenovirus membrane penetration and virion morphology changes.
Main Methods:
- Infection of KB cells with purified human adenovirus type 2.
- Observation of virion behavior using electron microscopy.
- Inactivation of virions with heat and antibodies prior to cell inoculation.
Main Results:
- Adenovirus type 2 directly penetrates plasma membranes, releasing virions into the cytoplasm.
- Virion morphology changes during plasma membrane penetration.
- Intact cells are essential for membrane penetration and morphological alteration; isolated membranes do not support these events.
- Inactivated virions show reduced cytoplasmic entry but are still found in vacuoles and pinocytotic vesicles.
Conclusions:
- Human adenovirus type 2 utilizes a direct plasma membrane penetration pathway.
- This entry mechanism is dependent on cellular integrity and involves virion structural changes.
- Alternative uptake routes, such as endocytosis, may occur for inactivated virions.