Fig. 3

Coupling of T20 and M2e onto PapMV-SrtA nanoparticles. a To reveal the efficacy of coupling of peptides onto the PapMV vaccine platform, we performed a 5% Tris–Glycine SDS-PAGE. The coupling induced by the sortase is covalent, and induced a shift on the gel as compared with the WT PapMV CP. Western blot of SrtA-conjugated nanoparticles PapMV-SrtA-M2e and PapMV-SrtA-T20 revealed fusion of the peptide on the PapMV CP. Western blots were directed against the PapMV CP, the 6×H tag, or the M2e peptide, as indicated under each panel. To evaluate if coupling of the peptide affected the structure of the nanoparticles, we evaluated their size by DLS analysis (b), comparing PapMV-SrtA (54 nm) to conjugated PapMV-SrtA-M2e (43 nm) and PapMV-SrtA-T20 (52 nm) nanoparticles. We also used TEM of PapMV-SrtA-M2e (left) and PapMV-SrtA-T20 (right) nanoparticles to confirm that the rod shape was preserved after the coupling experiment