Electron microscopy of tubular assemblies associated with naturally occurring bovine rotavirus.

Three types of regularly constructed assembly have been observed by electron microscopy of rotavirus-containing faeces from naturally infected cattle. Two of the structures, designated rotatube 1 and rotatube 2 respectively, are tubular in nature, and the third, designated rotatube 3, takes the form of large relatively disorganized sheets of material exhibiting, in some areas, tubular characteristics. Rotatube 1 is a 'wide' tube of approximately 80 nm diameter, the wall of which is composed of a surface lattice of hexagonally arranged subunits. Rotatube 2 is a 'narrow' tube, half the diameter of the wide tube, and does not exhibit a strictly hexagonal surface lattice. The sheets of rotatube 3 material are composed of subunits arranged on an hexagonal lattice identical with that of rotatube 1. The dimensions and general structural characteristics of the three types of assembly indicate that they are composed of rotavirus capsid protein.