Fig. 1: Design and characterization of a mosaic array of heterotypic antigens on self-assembling nanoparticles.

a, Design of hemagglutinin (HA) RBD–np. Alteration of residue 98 (Y98F) was made to abolish the sialic acid–binding property of hemagglutinin. Ag, antigen; SP, signal peptide; T/C, transmembrane/cytoplasmic domains. b, Negative-stain electron-microscopy images of self-assembled hemagglutinin RBD–np. RBD–np were made using either single building blocks (left and middle) or two different building blocks (right). Shown are representative images from one experiment. c, Antigenic characterization of RBD–np by immunoprecipitation (IP). The monoclonal antibodies 3u-u (anti-NC99), 2D1 (anti-CA09) and C179 (anti–hemagglutinin stem) were used to pull down NC99 RBD, CA09 RBD and hemagglutinin stem (control), respectively. Similar results were obtained from two independent experiments. d, Schematic model of ferritin-based nanoparticle. Twenty-four spatially dispersed antigens (colored individually) are displayed on the surface. Positions 2–6 are localized within 100 Å of position 1. e, Ferritin nanoparticle snub cube net with positions numbered similarly to the numbering in d. Connected lines indicate adjacent positions located within 50–100 Å. f, Twenty-four positions are colored according to the chromatic number (three) to avoid location of the a color within a 100-Å radius of the same color. g, Simulated likelihood of homologous antigen pairs made within a 100-Å radius on a single particle by using 2, 4, 6 or 8 different building blocks (valence).