Structure of the measles virus hemagglutinin bound to its cellular receptor SLAM

The measles virus hemagglutinin (MVH) promotes viral attachment to host cells via interaction with signaling lymphocyte activation molecule (SLAM). Now the crystal structure of MVH head domain in complex with the distal domain of SLAM, together with functional work, reveals the details of this interaction and explains the effectiveness of the currently used vaccine. Measles virus, a major cause of childhood morbidity and mortality worldwide, predominantly infects immune cells using signaling lymphocyte activation molecule (SLAM) as a cellular receptor. Here we present crystal structures of measles virus hemagglutinin (MV-H), the receptor-binding glycoprotein, in complex with SLAM. The MV-H head domain binds to a β-sheet of the membrane-distal ectodomain of SLAM using the side of its β-propeller fold. This is distinct from attachment proteins of other paramyxoviruses that bind receptors using the top of their β-propeller. The structure provides templates for antiviral drug design, an explanation for the effectiveness of the measles virus vaccine, and a model of the homophilic SLAM-SLAM interaction involved in immune modulations. Notably, the crystal structures obtained show two forms of the MV-H–SLAM tetrameric assembly (dimer of dimers), which may have implications for the mechanism of fusion triggering.