Figure 1.
Overview of alphavirus structure.
(a) A cutaway isosurface representation of the alphavirus Sindbis viewed along two-fold axis. Structure determined by cryo-EM and 3D reconstruction. The virion consists of three concentric layers: the glycoprotein spikes (blue) embedded in the lipid bilayer (green), and the nucleocapsid core (orange) which consists of the capsid protein and RNA genome. Both glycoprotein and the core are arranged in a T = 4 surface lattice. (b) Each spike is a trimer of E1 and E2 heterodimers. Shown are two heterodimers in gray and one with the atomic trace. The cytoplasmic domain of E2 interacts with capsid protein. OM, outer membrane. IM, inner membrane. Scale bar, 5 nm.