In this study, we have focused on two distinct pVNPs-based sys-tems: Potato virus X (PVX), the type member of the genus Potexvirus(Alphaflexiviridae family), and Tomato bushy stunt virus (TBSV),the prototype member of the genus Tombusvirus (Tombusviridaefamily). Both viruses have a monopartite single stranded, positive-sense RNA genome. PVX is a flexible filamentous virus of ∼500 nmin length and 15 nm in diameter, constituted by approximately1300 units of a unique coat protein (CP). TBSV is a spherical virus ofabout 30 nm in diameter with 180 copies of the CP self-assembledto form a T = 3 icosahedral symmetry.Both systems have been extensively explored as nanocarriersfor drug targeting to tumour cells. CP genetic engineering can beused to incorporate moieties for the covalent binding of exogenousmolecules (chemical derivatization strategy) or to display peptidesequences that bind selectively to a specific receptor overexpressedon cancer cells (genetic engineering strategy). For instance, PVX andTBSV CP have been engineered to display heterologous polypeptideat their N- or C-terminus respectively [12–14]. Internal sequenceregions generating external structure loops following CP foldinghave been used for the same purpose with Cowpea mosaic virus