Abstract
Viruses show ultrastructural changes during viral assembly and budding processes in which viral genome and proteins are systemically assembled. Electron microscopy is the only way that enables us to observe such ultrastructural changes. We have investigated the mechanisms of Ebola and influenza virion formation by electron microscopy. We have elucidated the roles of each Ebola virus protein in viral assembly and budding as well as the mechanisms of genome packaging of influenza A viruses.