The structure of mouse-Elberfeld virus: a model.

It is proposed that the capsid structure of mouse-Elberfeld (ME) virus, a small icosahedral ribonucleic acid containing picornavirus, is determined by 60 identical protein subunits; each of the latter is composed of several non-identical polypeptide chains. Icosahedral symmetry in a 60-subunit shell allows three types of specific intersubunit bonding contacts which establish its axes of two-, three-, and fivefold symmetry, respectively. Of these three bonding types, two are sufficient to specify a complete shell. We interpret the possible identity of some discrete supramolecular structures involved in the biosynthesis of poliovirus and in the degradation of ME virus in the context of stepwise formation or disruption of two different types of specific intersubunit bonding contacts.