2.3 Capsid protein (CP) purification
The native BMV virions were disassembled to obtain the CP protein needed to synthesize the VLPs. First, the BMV virions were dialyzed against the disassembly buffer (0.5 M CaCl2, 50 mM Tris-HCl, pH 7.4) for 5 h. Then, the resulting disassembled CP was centrifuged at 50,000 rpm, 4°C for 4 h. After centrifugation, the supernatant containing the CP was collected in 0.5 mL fractions. The CP purity of the fractions was estimated using the A280/A260 nm quotient. The best fractions (A280/A260≥ 1.6) were combined and dialyzed against the protein buffer (1 M NaCl, 20 mM Tris-HCl, pH 7.2) for 2 h. Finally, the dialyzed CP was recovered and then quantified by absorbance using the CP extinction coefficient.