(a) Schematic representation of individual components and assembled nanoparticle (left). Nanoparticle assembly tests were performed at different temperatures and the assembly efficacy was assessed using Native PAGE. NP, nanoparticle; ABC, antigen-bearing component; AC, assembly component; (right). (b) Negative stain EM analysis of purified nanoparticles. Representative raw micrographs, 2D class averages and 3D reconstructions are shown for BG505-SOSIP-T33_dn2 (left), -T33_dn10 (middle) and -I53_dn5 (right) nanoparticles. 3D maps are segmented and color-coded (BG505 SOSIP, gray; antigen-bearing component, orange; assembly component, blue). Particle diameters and the average apex-apex distance between the two closest neighboring Env trimers are shown for each nanoparticle. These data are also described in Ueda, Antanasijevic et al., 2020 [38]. (c) BLI analysis of antigenicity of assembled nanoparticles compared to the BG505-SOSIP.v5.2(7S) trimer.