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[15].