Intracellular delivery: exploiting viral membranotropic peptides

Recent advances in the understanding of cellular and molecular mechanisms of the pathogenesis of several diseases offer the possibility to address novel molecular targets for an improved diagnosis and therapy. In fact, in order to fulfill their function, macromolecular drugs, reporter molecules, and imaging agents often require to be delivered into specific intracellular compartments, usually the cytoplasm or the nucleus. From a medical perspective, biological membranes represent a critical hindrance due to their barrier-like behaviour not easily circumvented by many pharmacologically-active molecules. Therefore, identifying strategies for membrane translocation is essential. Several technologies have been designed to improve cellular uptake of therapeutic molecules, including cell-penetrating peptides (CPPs). These peptides, which are able to efficiently translocate macromolecules through the plasma membrane, have attracted a lot of attention, and new translocating peptides are continuously described. In this review, we will focus on the viral derived peptides, and in particular those derived by viral entry proteins that may be useful as delivery vehicles due to their intrinsic properties of inducing membrane perturbation.