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Effect of formamide on the capsid morphology of adenovirus types 4 and 7
Abstract:
Treatment of adenovirus types 4 and 7 with formamide disrupted the virions, degrading the capsids into predominantly single capsomers. As shown by electron microscopic observation, disruption proceeded in the following sequence: (i) reduction of the electron density of the virions, suggesting release of an internal component; (ii) progressive cleavage of the capsid into two or more segments and the formation (type 7 only) of capsomer "sheets"; (iii) final cleavage of the capsid into single or groups of a few capsomers. The sequence appeared similar for both adenoviruses; for both types, the rate and extent of disruption were dependent on the formamide concentration, but type 7 was more easily disrupted than type 4 by short-term (5 to 10 sec) treatment at the low (10%) concentration. At 30% formamide, the intercapsomer bonds of either type were fully cleaved, and the capsids were completely degraded into predominantly single capsomers. Pretreatment with formaldehyde did not prevent this degradation. Under suitable conditions, virus-derived remnants can be observed among the breakdown products. These remnants have been shorn of capsomers and presumably represent intact internal nucleoprotein.
Insights
Formamide treatment effectively degrades adenovirus capsids into individual capsomers. Adenovirus type 7 is more susceptible to this disruption than type 4, revealing internal viral components.
Area of Science:
- Virology
- Structural Biology
- Biochemistry
Background:
- Adenoviruses are common human pathogens.
- Understanding adenovirus structure is crucial for antiviral development.
Purpose of the Study:
- To investigate the effects of formamide on adenovirus types 4 and 7.
- To elucidate the mechanism and sequence of capsid disruption.
Main Methods:
- Electron microscopy was used to observe the disruption process.
- Adenovirus types 4 and 7 were treated with varying concentrations of formamide.
Main Results:
- Formamide treatment degraded adenovirus capsids into predominantly single capsomers.
- Adenovirus type 7 showed greater susceptibility to formamide disruption than type 4.
- A sequential disruption process was observed, involving internal component release and capsid cleavage.
- Virus-derived remnants, likely internal nucleoprotein, were identified.
Conclusions:
- Formamide is an effective agent for adenovirus capsid disruption.
- The study provides insights into adenovirus structural integrity and breakdown mechanisms.
- Findings may inform strategies for antiviral therapies targeting adenovirus.