The complex arrangements of macromolecules in the virus shell are minute marvels of molecular architecture. Specific requirements of each type of virus have resulted in a fascinating apparent diversity of organisation and geometrical design. Nevertheless, there are certain common features and general principles of architecture that apply to all viruses.
A typical cryo-EM micrograph of VSV virions at 98,000× magnification. The trunk portion is marked by the boxes. (Inset) Incoherent average of Fourier transforms of all raw images showing the layer lines. 5
The proposed spiral assembly pathway of large icosahedral capsids. Isosurfaces of CroV (A), PBCV-1 (B), and CIV (C) cryo-EM maps were centered on the 5-fold axis. Capsomers in all three panels are colored based on their orientation in red, blue, green, cyan, and orange. The pentameric capsomers are depicted as purple stars. (D) Schematic diagram showing the right-handed spiral assembly pathway following arrows (1) to (6), with multiple extensions (7) of the trisymmetrons to form similar patterns as shown in (A–C). One set of capsomers (red) is labeled by Roman numerals if they are part of the pentasymmetron and by Arabic numerals if they are part of a trisymmetron.
A 4.4 Å resolution, icosahedrally averaged reconstruction of PBCV-1 2
Capsomer Arrangement of Mimivirus 2
(A) AFM image of defibered virus showing one face of the virion with irregular cracks along the edges of the face.