Cover photograph (Copyright © 2004, American Society for Microbiology. All Rights Reserved.): Predicted structure of the measles virus hemagglutinin. The predicted solvent-exposed surface is outlined in transparent grey. The six beta sheets arranged cyclically around the axis like blades of a propeller are shown in different colors. The residues necessary for SLAM-induced fusion, all surface exposed and accessible from the top of the molecule, are shown in red or gold. The residues necessary for CD46-induced fusion, all located in or near one beta sheet and accessible from the side, are shown in blue or pink. (See related article in January 2004: vol. 78, issue 1, p. 302.)