STRUCTURE OF FOOT-AND-MOUTH-DISEASE VIRUS CAPSID

Electron microscope images of negative-stained particles of FMDV have been analyzed. The viral capsid appeared to be a pliant structure composed of monomers having an average width of about 2.5 nm and a length of 4 nm. Upon capsid disruption, a sequential and nonrandom detachment of skullcaps was observed. These skullcaps are presumably clusters of monomers, and they could be similar to those predicted for the 13-14 S subunits described for other picornaviruses. If this were the case, each FMDV capsid would be constituted by twelve skullcaps, making a total of 180 monomeric units for the outer part of the protein shell. However, the FMDV skullcap, compared with other picornavirus subunits, has a lower sedimentation coefficient (12 S) and shows high stability upon treatment with urea without production of the 4-5 S component characteristic of other related viruses. © 1979.