Norovirus Capsid Protein-Derived Nanoparticles and Polymers as Versatile Platforms for Antigen Presentation and Vaccine Development

Figure 1. Lineage structures of norovirus capsid protein or viral protein 1 (VP1) and various nanoparticles derived from full-length or truncated VP1. The N-terminal shell (S) (green) and the C-terminal protruding (P) (dark blue) domains with a short flexible hinge (light blue) in between (with amino acid numbers based on GI.1 Norwalk virus VP1) are shown. (A) Production of full-length norovirus VP1s via a eukaryotic expression system self-assembles into virus-like particles (VLPs). (B) Production of the S or P domain via the Escherichia coli expression system self-assembles into S or P nanoparticles.

Figure 2. Self-formation of the norovirus S60 nanoparticle and its applications as a platform for epitope and antigen presentations. (A) Expression of the norovirus S domain (orange) with a flexible hinge (green) self-assembled into the S60 nanoparticle, with 60 hinges being exposed on the surface. (B) When the Hisx6 tag (His, dark blue) was fused to the hinge (H, green) through a linker (L, purple), the fusion proteins self-assembled into the S60 nanoparticle, with 60 Hisx6 tags being displayed on the surface. (C) When a rotavirus-neutralizing antigen VP8* (cyan) was fused to the hinge, the fusion proteins self-assembled into chimeric S60–VP8* nanoparticle, with 60 VP8* antigens being displayed on the surface. (D) Transection structure of the chimeric S60–VP8* nanoparticle, reconstructed by electron cryo-microscopy (cryo-EM), showing the interior S60 shell in red, yellow, and green, as well as the protruding VP8* antigens in cyan and green.

Figure 3. Self-formation of norovirus P24 nanoparticle and its application as a platform for antigen presentation. (A) Norovirus P domain (green) self-assembled into the P24 nanoparticle. (B) When the rotavirus-neutralizing antigen VP8* (blue) was fused to a surface loop of the norovirus P domain (green), the P–VP8* fusion proteins self-assembled into the P24–VP8* chimeric nanoparticle, with 24 copies of the VP8* antigens being displayed on the surface of the chimeric P24–VP8* nanoparticle.