FANCB and infection: To thoroughly understand the structural mechanism of how D5 binds EV71 and inhibits its infection, we determined four cryo-EM structures of D5 full IgG or its Fab in complex with EV71 mature virion (F-particle), procapsid (E-particle) or VLP, i.e. F-particle-Fab, F-particle-IgG, E-particle-Fab and VLP-IgG (Fig 1A–1D and S1 Table).