Electron microscopy study of reovirus reaction cores

Area of Science:

• Molecular Biology
• Virology
• Microscopy

Background:

• Reoviruses are non-enveloped viruses with segmented dsRNA genomes.
• Understanding viral RNA synthesis is crucial for developing antiviral strategies.
• Previous methods lacked sufficient resolution to visualize nascent RNA structures.

Purpose of the Study:

• To visualize reovirus cores and their synthesized RNA with enhanced contrast.
• To investigate the structure and synthesis process of reovirus messenger RNA (mRNA).
• To identify potential sites of RNA synthesis on the reovirus core.

Main Methods:

• A combined staining and shadowing technique was employed.
• Electron microscopy was used to observe reovirus particles.
• Analysis focused on reovirus cores after limited RNA synthesis.

Main Results:

• Enhanced contrast was achieved for both reovirus cores and synthesized RNA.
• Many reovirus cores exhibited more than 10 nascent RNA strands.
• Nascent mRNA molecules varied in length, with many forming loops.
• RNA extrusion sites were identified on the core surface.

Conclusions:

• The combined staining and shadowing method effectively visualizes reovirus RNA synthesis.
• Reovirus mRNA synthesis occurs simultaneously at multiple sites on the core.
• The 12 hollow projections on the reovirus core surface are likely sites of RNA extrusion.