Advancing biological understanding of the poxvirus scaffold through breakthroughs in cryo-electron microscopy

Poxvirus morphogenesis involves extensive cellular membrane remodeling and assembly intermediates that have remained difficult to resolve at the molecular level. Progress in cryo-electron microscopy has been pivotal in characterization of immature poxvirus assembly by enabling direct visualization of scaffold architecture across scales. Structural analyses of in vitro assemblies revealed that the scaffold protein of vaccinia virus D13 forms a curved, honeycomb lattice through specific intertrimer interactions, structural features that promote spherical geometry. Cryo-electron tomography extended this understanding to a cellular context by resolving lattice organization and scaffold removal during maturation, and by revealing the emergence of an internal palisade layer that reshapes the condensing core. Together, these studies indicate that scaffold-mediated curvature, membrane coupling, and sequential lattice deployment define virion size and final architecture. Continued convergence of in vitro and in situ cryo-EM with correlative and time-resolved methods promises deeper understanding of transient intermediates and may guide strategies that target assembly pathways for antiviral intervention.