Enveloped Viruses

Abstract

A distinguishing physical feature of many viruses is the presence of a host-derived lipid bilayer. This feature of the virus particle has important consequences for the assembly and release as well as the entry pathway for a particular virus. Significant advances have been made in our understanding of enveloped viruses. This progress has been due primarily to advances in structural and cell biology. Knowledge of virus structure has been aided in large part by the development of cryoelectron microscopy (cryo-EM) and imaging techniques and their linkage to independently determined atomic structures of virion components. Thus, although no X-ray crystallographic structure of an enveloped animal virus has yet been solved, several enveloped virus structures are now approaching atomic resolution, or perhaps more appropriately, pseudo-atomic resolution. Improvements in techniques as well as reagents in cell biology have also provided insights into the morphogenesis of enveloped viruses. Confocal microscopy and other imaging techniques have been used to elaborate the pathways and interactions that virion components utilize in their path toward assembly and eventually budding. In this review, some of the general features of enveloped virus structure and assembly are discussed and several icosahedral enveloped virus examples are examined.