Recent advances in the structure and assembly of non-enveloped spherical viruses

Non-enveloped spherical viruses (NSVs) are characterized by their highly symmetrical capsids that serve to protect and encapsulate the genomes. The stability and functionality of the capsids determine their ability for survival and proliferation in harsh environments. Over four decades of structural studies using X-ray crystallography and NMR have provided static, high-resolution snapshots of several viruses. Recently, advances in cryo-electron microscopy, together with AI-based structure predictions and traditional methods, have aided in elucidating not only the structural details of complex NSVs but also the mechanistic processes underlying their assembly. The knowledge thus generated has been instrumental in critical understanding of the conformational changes and interactions associated with the coat proteins, the genome, and the auxiliary factors that regulate the capsid dynamics. This review seeks to summarize current literature regarding the structure and assembly of the NSVs and discusses how the data has facilitated a deeper understanding of their biology and phylogeny.