Fig. 1: Design and characterization of group 1 H1 stem nanoparticle variants.

a Comparison of N-linked glycosylation pattern of group 1 and group 2 HA stem. Surface renderings of HA trimer for a representative group 1 HA (A/Solomon Islands/06 (H1N1), PDB: 3SM5, left) and representative group 2 HA (A/Finland/486/04 (H3N2), PDB: 2YP5, right). One monomer is colored in blue for visibility. The terminal N-acetylglucosamine (GlcNAc) moiety for each glycan is modeled in green and residue positions are labeled according to the H3 numbering. Yellow areas designate the approximate location of the CR6261 epitope on each HA. b Amino acid sequence alignment of N-terminal portion of HA1 of H1 (A/New Caledonia/20/99), H3 (A/Finland/486/04) and designed variants gN38 and R38. Dots and dashes indicate residues identical to H1 and gaps, respectively. c Cryo-electron microscopy structures of H1 stem nanoparticle (H1ssF WT) and its variants H1ssF gN38 and H1ssF R38. Nanoparticles are depicted along the 2-fold symmetry axis. Side views of HA stem trimeric spikes are shown below each nanoparticle. The maps were low-pass filtered to a resolution of 7 Å for comparison. Scale bar indicates 5 nm. d Antigenicity of H1 stem nanoparticle variants. ELISA binding curves are shown for mAbs specific to group 1 stem (CR6261, 02-1H01 and C179), group 2 stem (CR8020), both group 1 and 2 stems (FI6v3, MEDI8852), or irrelevant RSV F protein (D25). Source data are provided as Source Data file.