Flock House Virus: A Model System for Understanding Non-Enveloped Virus Entry and Membrane Penetration

The means by which non-enveloped viruses penetrate cellular membranes during cell entry remain poorly defined. Recent findings indicate that several members of this group share a common mechanism of membrane penetration in which the virus particle undergoes programmed conformational changes, leading to capsid disassembly and release of small membrane-interacting peptides. Flock House Virus (FHV), a member of the nodaviridae family, offers some unique advantages for studying non-enveloped virus entry. The simplicity of the FHV capsid, coupled with a robust reverse genetics system for virus expression and an abundance of structural and biochemical data, make FHV an ideal model system for such studies. Here, we review the FHV atomic structure and examine how these molecular details provide insight into the mechanism of FHV entry. In addition, recent studies of FHV entry are discussed and a current model of FHV entry and membrane penetration is presented. A complete understanding of host cell entry by this minimal system will help elucidate the mechanisms of non-enveloped virus membrane penetration in general.