Cover photograph (Copyright © 2001, American Society for Microbiology. All rights reserved.): Structure of the cucumber necrosis virus (CNV) particle (T=3 icosahedron), showing areas of the capsid important in fungal vector recognition. Areas in yellow correspond to amino acid residues in the particle quasi-threefold axis that are mutated in naturally occurring CNV transmission mutants. The mutations also affect attachment to the outer membrane of the fungal zoospore, suggesting a role for these sites in receptor recognition. Three-dimensional coordinates for the CNV structure were obtained by homology modeling, using tomato bushy stunt virus coordinates and the program MODELLER. Surface rendering from atomic coordinates is radially depth cued by color and was created with the program GRASP. (See related article on page 5576.)