Fig. 1: CPMV structure and nanoscale characterization.

a CPMV structure: Cowpea mosaic virus (CPMV) has a bipartite ssRNA genome; the RNA-1 and RNA-2 are separately encapsulated into isometric 30 nm-sized capsids comprised of a small (S) and large (L) coat protein. CPMV RNA-1 encodes the 32 K protease cofactor, 58 K helicase, VPg, 24 K protease, and 87 K RNA-dependent RNA polymerase. RNA-2 encodes for the movement protein (MP), and the L and S coat proteins. PDB: 1NY7, CPMV structure generated with UCSF’s ChimeraX. b–j Nanoparticle characterization: b UV–VIS spectrum and the A260/280 ratio; intact CPMV have an A260/280 ratio of 1.7 ± 0.1. c, d DLS and AF4-DLS show a monodisperse ~30 nm-sized nanoparticle. e SEC shows the typical elution profile from a Superose 6 Increase column with a ~1.7 A260/280 ratio. f, g TEM of negatively stained CPMV and CryoEM of CPMV confirms the presence of monodisperse ~30 nm-sized CPMV. Scale bars at 50 nm and 100 nm, respectively. h Native gel visualized under UV light with RNA staining (GelRed) and white light after protein staining (Coomassie Blue); RNA and protein co-migrate, which indicates stable encapsulation of the RNA into the capsid. Denaturing gel: pure separations of CPMV L and S coat protein (L-CP and S-CP) at ~42 kDa and ~24 kDa, respectively. i Total RNA sequencing of RNA extracted from CPMV indicates 95% purity with sequences aligning with CPMV RNA-1 and RNA-2 [NC_003549.1 and NC_003550.1], 3% is unknown, and 0.4% aligns with black-eyed pea host. j Total protein sequencing of purified CPMV indicates 96.1% purity with sequences aligning with the CPMV coat proteins, 1.5% aligned with black-eyed pea host, and 2.4% aligned with a mixture of homo sapiens and bacterial contaminants. k Endotoxin detection from purified CPMV. N = 3.