Electron microscopic studies on the connections between capsomers in the adenovirus capsid

Electron microscopic observation of negatively stained virions suggests that the interhexonal spaces within the adenovirus capsid are bridged by interhexonal connective elements. Similar connections are also detected between pentons and the five peripentonal hexons. Examinations of electron micrographs by Markham's rotational integration technique reveals the presence of a regular network of the connective elements between the capsomers in the whole capsid. The length of these connections corresponds to about one-third of the diameter of the hexons. The connections consist of two approximately parallel elements, thus every hexon is joined to its six nearest neighbours by 12 connections. A possible mutual orientation pattern of the connective elements in the whole capsid is presented on a tentative virus model.