The core radius is around 10.5 nm, and the overall particle radius of the AP205 VLP is around 13.6 nm, resulting in a shell thickness of 3.1 nm. This thickness and radius is in reasonable agreement with previous studies, reporting a radius of about 14 nm. The size obtained from SAXS analysis is also in good agreement with the results from DLS, demonstrating a hydrodynamic radius (RH) of 16.7 ± 0.1nm from the Contin fit with intensity weighting (see Figure and Figure ). The influence of the buffer ionic strength AP205 VLP at reduced ionic strength was characterized in a buffer containing only 5 mM total phosphate concentration and 10 mM NaCl (details on the composition can be found in the SI).