Naturally-occurring nanoparticles such as viral-based particles hold great potential in the nanomedicine field. There exterior and interior can be genetically and chemically modified with various moieties to impart new functionalities. Furthermore, the internal space can be used as a reaction container or as a drug carrier for high payload depending on the shape of the viral nanoparticles. Such particles have shown no toxicity in vivo and in vitro system deeming them as safe, biocompatible and cheaper alternative to the synthetic counterparts.