Identification of rotavirus particle types

Area of Science:

• Virology
• Microscopy
• Cell Biology

Background:

• Rotavirus causes significant gastroenteritis globally.
• Understanding rotavirus particle morphology is crucial for developing antiviral strategies.
• Previous studies have described various rotavirus particle forms, but their interrelationships remain unclear.

Purpose of the Study:

• To elucidate the relationship between different rotavirus particle morphologies observed via negative-contrast electron microscopy and thin-section electron microscopy.
• To characterize the enveloped and non-enveloped forms of rotavirus particles within infected cells.
• To identify the nature of type IV particles observed in lysosome-like bodies.

Main Methods:

• Negative-contrast electron microscopy of purified rotavirus particles.
• Thin-section electron microscopy of simian rotavirus SA11-infected cell lysates.
• Analysis of purified single-shelled and double-shelled rotavirus particles.

Main Results:

• Two main particle types were observed: single-shelled and double-shelled.
• Double-shelled particles were the predominant non-enveloped form in thin sections.
• Enveloped particles, though rare in stocks, comprised approximately 10% of particles within infected cells, suggesting a transient nature.
• Type IV particles in lysosome-like bodies were identified as subviral particles derived from input virions.

Conclusions:

• The study clarifies the morphological relationships of rotavirus particles, identifying double-shelled particles as the primary non-enveloped form.
• The enveloped rotavirus particle is likely a transient intermediate form, with the envelope being shed in the endoplasmic reticulum.
• Type IV particles represent degraded input virions within cellular compartments.