Dr Juan Fontana is an Associate Professor at the University of Leeds and has over 15 years’ experience employing cryo-electron microscopy to unravel the structure of viruses and macromolecules. Juan graduated in Biochemistry at the Universidad Autonoma of Madrid in 2003. During his PhD (2004 – 2009), in the lab of Cristina Risco (National Centre for Biotechnology, Madrid, Spain), he characterised the replication complexes of Bunyamwera and Rubella viruses. This work allowed him to elucidate the mechanisms by which viral macromolecular complexes interact with cellular components to create viral factories and to propose novel working models for each replication complex. As a post-doc (2009 – 2016), with Alasdair Steven (National Institutes of Health, USA) he worked on enveloped virus entry and morphogenesis. For example, he 1) analysed the structural intermediates of influenza virus hemagglutinin and M1 matrix proteins prior to viral fusion; 2) studied HIV morphogenesis and how this process can be blocked by different drugs and mutations; 3) structurally characterised the shell protein of a bacterial protein-bound nanocompartment, which assembles as a virus-like icosahedral shell to protect bacteria from oxidative stress through iron sequestration. In 2016 he started his independent laboratory as a University Academic Fellow at the University of Leeds, and he became an Associate Professor in 2021. As a PI at Leeds, Juan has: 1) characterised the structure of Bunyamwera virus ribonucleoproteins; 2) characterised the structural changes in the viral spikes induced by K+ during Bunyamwera virus entry; and 3) structurally characterised heterogeneous ribosomes isolated from different D. melanogaster tissues.