Fig. 5.

Recombinant protein construction and PNp generation and characterization: (A) Cartoon models of the construction and expression of recombinant proteins 4MtG, hrH1, and hrH3. The numbering of hrH1 and hrH3 are based on the amino acid sequences of PR8 and Aic HA, respectively. Above arrows indicate the location of flexible linkers in 4MtG. Dashed lines indicate the sequences replaced with linkers shown below. Below arrows indicate the site-mutations, V325C and S438C in hrH3. (B) Schematic diagram of Uni4MC (desolvated 4MtG PNp) fabrication. Recombinant 4MtG protein was self-assembled into PNps by desolvation as described in the Materials and Methods. (C) Schematic diagram of double-layered nanoparticle generation. An additional layer of trimeric hrHA proteins was crosslinked onto the desolvated Uni4MC PNp surface via DTSSP crosslinking. Adapted from Deng, Lei, et al. "Double-layered protein nanoparticles induce broad protection against divergent influenza A viruses." Nature communications 9.1 (2018): 1–12.http://creativecommons.org/licenses/by/4.0/.