Positive-strand RNA virus genome replication organelles: structure, assembly, control.

Area of Science:

• Virology
• Molecular Biology
• Cell Biology

Background:

• Positive-strand RNA ((+)RNA) viruses, including SARS-CoV-2 and Hepatitis C virus, cause significant global health challenges.
• (+)RNA viruses replicate within specialized virus-induced replication organelles (ROs), which are also sites for viral evolution.
• Targeting viral replication mechanisms within ROs is crucial for developing antiviral strategies.

Purpose of the Study:

• To elucidate the structural and functional roles of viral RNA replication proteins in (+)RNA virus replication.
• To investigate the formation and function of 'crown' structures at the interface of ROs and the cytosol.
• To understand how these structures facilitate viral RNA synthesis, immune evasion, and progeny virion formation.

Main Methods:

• Utilized cryo-electron microscopy (cryo-EM) to visualize the high-resolution structure of viral replication complexes.
• Analyzed the assembly and organization of viral RNA replication proteins forming 'crown' structures.
• Investigated the functional implications of these structures in viral RNA synthesis and host-pathogen interactions.

Main Results:

• Cryo-electron microscopy revealed striking ringed 'crown' structures formed by viral RNA replication proteins at RO-cytosol junctions.
• These crowns are essential for directing RO vesicle formation, viral RNA synthesis (both negative and positive strands), and RNA capping.
• The structures play a role in the virus's ability to evade the host's innate immune system and facilitate the transfer of viral RNA for replication and packaging.

Conclusions:

• Viral 'crown' structures are key determinants of (+)RNA virus replication organelle biogenesis and function.
• Understanding crown assembly and function offers critical insights into viral pathogenesis and potential therapeutic targets.
• Further research into these structures may unlock novel strategies for controlling (+)RNA viral infections and exploring beneficial viral applications.