Fig. 1: Breadth and specificity of EV71-specific antibody response in donor C.

a Serological response against wild-type EV71 and its epitope variants. The virus (11-96023_VP3 E81K) was an escape variant selected with neutralizing antibody in vitro¹³ and the TW-1745_VP3 E81K and TW-1745_VP1 D110G were generated in vitro by introducing the residue substitution into an infectious cDNA clone of EV71 (strain TW-1745, GenBank accession number KT354870.1) via site-directed mutagenesis¹³. Donor C developed a strong antibody response at day 9 after illness onset which focused on the threefold plateau epitope of EV71 capsid. A post-EV71 infection serum (day 10 of illness onset) from another paediatric donor, a post-echovirus 11 infection serum (day 10 of illness onset) and a post-influenza virus infection serum (day 11 of illness onset) were included in the experiment. The neutralization assay was carried out twice with equivalent results. Source data are provided as a Source Data file. b Characterization of 19 plasmablast-derived EV71-specific monoclonal from donor C, measured by the flow cytometry (FCM), ELISA, immunoprecipitation (IP) and neutralization assays. Those marked by stars bound to purified native viruses in the direct ELISA. Eight of 19 EV71-specific antibodies reacted to conformational epitopes on the viral capsid. A distance tree (cladogram) was constructed by neighbour-joining methods (1000 bootstrap replications) using heavy chain variable domain sequences of 19 EV71-specific human monoclonal antibodies (SeaView software). Bootstrap support values are shown for major nodes on the tree. c Mapping of threefold plateau epitope (VP3 E81 coloured in red, VP3 S74 coloured in green, VP2 D225 coloured in blue and VP2 E72 coloured in orange) based on the EV71 capsid structures 4CEY. The side view of a cartoon diagram of EV71 icosahedral asymmetric unit and the surface view of a pentamer are shown with the fivefold vertex at the centre and created using the software program PyMOL. The capsid VP1 protein is coloured in black, VP2 coloured in grey and VP3 coloured in white. The contact region for hSCARB2 cellular receptor¹² is coloured in cyan.