Cover photograph (Copyright © 2004, American Society for Microbiology. All Rights Reserved.): Electron cryo-microscopy and image reconstruction of four types of Flock House virus particles that differ in RNA and protein content revealed almost identical capsid shells (gray). Despite differences in the encapsidated RNA (electrophoretic profiles), a substantial fraction of the packaged nucleic acid in all four types of particles was organized as a dodecahedral cage of duplex RNA. (See related article on page 2897.)