Tuning nanoscale lipid clustering controls influenza viral binding

Abstract

Influenza virus attaches to cells by binding to sialylated glycans. Subsequent endocytosis of the virus and endosomal maturation leads to a conformational change in the hemagglutinin coat protein that ultimately results in membrane fusion and release of the viral genome into the host cytoplasm, where it is trafficked to the nucleus and commences replication. Individual hemagglutinin-glycan binding affinities are weak (Kd approximately mM), so multivalency is key to viral attachment. Receptor density or clustering has previously been shown to affect influenza binding, but the overall spatial heterogeneity of both plasma and endosomal membranes has not been fully addressed. Here, we show that nanoscale lipid clustering can increase local concentration of glycosphingolipids and greatly enhance influenza viral binding in a way that macroscopic phase separation does not, and that binding avidity is dependent on the spatiotemporal scales of this clustering. This clustering is driven by sphingolipids and cholesterol and the nanoscale lipid environment of these clusters persists to affect the viral entry process. This finding demonstrates how fine receptor patterning can drive infection and illustrates the importance of tuning spatial scale in liquid-liquid phase separation.