Capturing intermediates and membrane remodeling in class III viral fusion

Area of Science:

• Virology
• Structural Biology
• Cell Biology

Background:

• Enveloped viruses utilize glycoproteins to mediate fusion with host cell membranes for entry.
• Vesicular stomatitis virus (VSV) glycoprotein (G) serves as a model for class III viral fusion proteins.
• The conformational changes and intermediate structures of VSV G during fusion remain poorly understood.

Purpose of the Study:

• To visualize the membrane fusion pathway of VSV using cryo-electron tomography (cryo-ET).
• To characterize the refolding intermediates and conformational changes of VSV glycoprotein G.
• To gain mechanistic insights into class III viral fusion processes.

Main Methods:

• Incubation of VSV virions with liposomes mimicking late endosomes at pH 5.5.
• Cryo-electron tomography (cryo-ET) for high-resolution imaging of fusion intermediates.
• Reconstruction of sequential conformational changes in VSV glycoprotein G.

Main Results:

• Visualization of VSV's membrane fusion pathway intermediates.
• Observation of VSV G trimer disassembly into monomers and dimers exploring diverse conformations.
• Identification of extended fusion intermediates engaging target membranes, leading to viral uncoating.

Conclusions:

• The study provides detailed mechanistic insights into class III viral fusion.
• Characterized intermediates offer a basis for understanding viral entry.
• Findings support structure-based design of novel antiviral therapeutics targeting viral fusion.