“Visualizing the conformational dynamics of viral membrane fusion machines".

Influenza hemagglutinin (HA) is the canonical type-I viral envelope glycoprotein, and provides a template for the membrane fusion mechanisms of numerous viruses. Here, using single-molecule Förster resonance energy transfer (smFRET) imaging we directly visualized conformational changes of HA trimers on the viral surface. These findings reveal the coordination between receptor binding and HA conformational dynamics, which facilitates efficient fusion.