Cover photograph (Copyright © 2002, American Society for Microbiology. All Rights Reserved.): One glycoprotein spike of Sindbis virus (blue) penetrating the phospholipid membrane bilayer (green) surrounding the nucleocapsid (orange and red). The spike consists of glycoproteins E1 (dark blue) and E2 (light blue) and can be distinguished by fitting the X-ray crystallographic structure (yellow) of E1 into the cryoelectron microscopy density. The transmembrane segments of E1 and E2 form a coiled-coil structure (orange). One hexamer of the nucleocapsid density has been fitted with the X-ray crystal structure (gray). (See related article on page 11645.)