Fig. 3: S-VLPs characterization shows a high number of S proteins on the particle surface with a glycan pattern similar to soluble S trimmers.

a Individual S-VLP image (positive contrast) was acquired by Cryo-EM. The portrayed VLP contains 20 peripheral S proteins. Individual S proteins are evident in the magnified image, protruding from the envelope with an average size of 20 nm. A 25 nm scale bar is displayed at the bottom of each image. b Schematic of calculation workflow from the measured arc length between two peripheral spikes to real Euclidian distance between spikes on the VLP core surface. c Reconstruction of S distribution on VLPs using the real Euclidian distance. VLP models correspond to core diameters of 40 nm/35 spikes, 50 nm/50 spikes, 60 nm/67 spikes, and 70 nm/86 spikes. d Compositional glycan identification of the S-VLP and recombinant soluble (SmT2v3) S proteins. The identity and proportion of 20/22 N-glycans were determined by LC–MS and presented in pie charts. See also Supplementary Fig. 3 and Supplementary Data file.