Adenovirus is enclosed by an icosaedral protein capsid composed of hexamerix proteins called hexons (240 in number) that form the plates and edges of the virion capsule while the icosaedral vertices are occupied by 12 pentons (each composed of five protein chains) bearing spikes, each containing three identical protein chains. Each spike bears a round knob at its end. The adenoviruses contain DNA and several proteins associated with it, like polypeptides V, VII, Mu, IVa2, protease and TP.