Figure 1 –

DCFHP design and validation. (A) DCFHP schematic showing the modifications made to convert SΔC-Fer into DCFHP in red. Receptor binding domain (RBD), N-terminal domain (NTD), S1/S2 cleavage site, S2’ cleavage site, fusion peptide (FP), heptad repeat 1 (HR1), as annotated. (B) SDS-PAGE gel showing purified DCFHP running as a monomer at the anticipated kDa molecular weight (ladder, shown left). (C) UV (yellow) and light scattering (grey) traces determined from SEC-MALS shows a homogenous nanoparticle peak with approximate molecular weight (dashed line) of 3.4MDa. (D) 3D reconstructed cryo-EM density maps of DCFHP, refined with octahedral symmetry. (E) Similar robust neutralization of Wuhan-1 SARS-CoV-2 pseudovirus with day 21 serum from mice immunized with either SΔC-Fer or DCHFP formulated with 500 μg alum and 20 μg CpG 1826, following a single immunization. Neutralization titers were assessed in a HeLa cell line expressing ACE2 and TMPRSS2. Data for 10 mice are presented as geometric mean titer and standard deviation. Assay limit of quantitation (LOQ) is shown as a dotted horizontal line.