Fig. 1: HA executes essential functions during the viral lifecycle and is a determinant of host tropism.
From: Host switching mutations in H5N1 influenza hemagglutinin suppress site-specific activation dynamics
A HA (blue) binds to SA receptors on the surface of host cells, initiating viral entry. Acidification of the endosome triggers a cascade of structural changes in HA that drive fusion of the viral and host cell membranes. B Adaptation to a human host requires changes to HA receptor specificity and acid stability. C Low pH induces large-scale structural rearrangement in HA2 (blue) and dissociation of the HA1 subunits (gray) (PDB 6Y5G, 1QU1). Figure partially created in BioRender. Kephart, S. (2025) https://BioRender.com/xz3ew0d.
