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Virus-receptor interaction in an adenovirus system
Abstract:
HeLa or KB cells each contain around 10(4) receptor sites for adenovirus type 2. These are inactivated by treatment of live cells with subtilisin. The receptor activity of the enzyme-treated cells is regained after 4 to 8 hr of incubation in complete medium. A technique that utilizes the difference in buoyant density between free virus and virus-receptor complex was developed to demonstrate receptor activity. Cellular fractionation revealed that receptors were confined mainly to the plasma membrane fraction and that negligible receptor activity could be demonstrated in enzyme-treated cells. Subtilisin probably did not penetrate the cell membrane; thus, the receptors are limited to the cell surface. Purified fiber of the virion completely prevents attachment of adenovirus types 2 and 5 to receptor sites at a ratio of 10(5) protein molecules per cell. Adsorption studies indicate that 10(5) to 10(6) receptor sites are available for the structural protein. The fiber does not affect attachment of poliovirus type 1.
Insights
Adenovirus type 2 uses specific cell surface receptors for attachment. These adenovirus receptors are located on the plasma membrane and can be temporarily inactivated by subtilisin treatment.
Area of Science:
- Virology
- Cell Biology
- Biochemistry
Background:
- HeLa and KB cells possess approximately 10^4 receptor sites for adenovirus type 2.
- Adenovirus receptors mediate viral entry into host cells.
Purpose of the Study:
- To characterize the nature and location of adenovirus type 2 receptors on host cells.
- To investigate the role of cell surface proteins in adenovirus attachment.
Main Methods:
- Enzymatic inactivation of cell surface receptors using subtilisin.
- Receptor activity regeneration through cell incubation.
- Buoyant density gradient centrifugation to separate virus-receptor complexes.
- Cellular fractionation to localize receptor activity.
Main Results:
- Subtilisin treatment inactivated adenovirus type 2 receptor activity.
- Receptor activity was regained after 4-8 hours of incubation.
- Receptors were primarily localized to the plasma membrane fraction.
- Purified adenovirus fiber protein inhibited virus attachment, suggesting its role in receptor binding.
- Fiber protein did not affect poliovirus type 1 attachment.
Conclusions:
- Adenovirus type 2 receptors are located on the cell surface, predominantly on the plasma membrane.
- The viral fiber protein is crucial for adenovirus binding to its specific cell receptors.
- Receptors are stable and can regenerate after temporary inactivation.