José Castón is group leader of the Viral Molecular Machines Laboratory at the National Center for Biotechnology (CNB-CSIC) in Madrid (Spain). He received his PhD in Biochemistry from the Universidad Autónoma of Madrid and was a postdoc at the laboratory of Alasdair Seven at the National Institutes of Health (Bethesda, MD, USA). In his research, he studies structure–function–evolutionary relationships of viral macromolecular complexes or nanomachines using three-dimensional cryo-EM. Structural analysis of viruses is complemented by study of mechanical properties by atomic force microscopy (AFM). These analyses offer new alternatives for the development of virus-based nanotechnological applications. Our group studies several viral systems with varying levels of complexity, with focus on a number of double-stranded RNA viruses such as birnaviruses (infectious bursal disease virus, IBDV), human picobirnavirus (HPBV) and several fungal viruses [Rosellinia necatrix quadrivirus 1 (RnQV1), Penicillium chrysogenum virus (PcV), and Saccharomyces cerevisiae virus L-A (ScV-L-A) among others], as well as single-stranded RNA viruses such as rabbit hemorrhagic disease virus (RHDV) and human rhinovirus (HRV).