Int'l Centre for Genetic Eng. and Biotechnology 162d ago

Abstract Cryo-electron microscopy (cryo-EM) has significantly advanced the field of structural virology, providing remarkable insights into the architecture and life cycles of both small and large viruses. This technique is especially impactful in studying picornaviruses and jumbo viruses, two groups that embody structural and biological extremes. Picornaviruses, including poliovirus and enteroviruses, are small, non- enveloped icosahedral viruses that have been extensively analysed using single-particle cryo-EM. This method has allowed for high-resolution reconstructions of their capsid proteins, identification of receptor-binding sites, and visualisation of conformational changes during viral entry and uncoating. In contrast, jumbo viruses—giant double-stranded DNA viruses that infect amoebae and other protists—present unique challenges due to their enormous size and complex structure. Cryo-EM has enabled the three-dimensional imaging of these megaviruses, uncovering intricate capsid arrangements, associated protein machinery, and the mechanisms of genome packaging. In this context, I will present a few examples of structural determinations achieved through cryo-EM for these viruses.