A. Schematic representation of a Levivirus. Many of the RNA hairpin loops are believed to be in contact with the coat-protein dimers. The position of the maturation protein in the drawing is arbitrary. Capsid shell has a thickness of 2 nm. Alloleviviruses contain an additional ?15 readthrough proteins in their virions. B. Escherichia coli bacterium with F-pili to which many MS2 phages have attached (arrows). Note that a single phage suffices for successful infection. Courtesy A.B. Jacobson.