Adenovirus. Computer graphic based on a transmission electron micrograph (TEM) of an adenovirus particle. This virus causes infection most frequently in the upper respiratory tract and eyes, with symptoms resembling a common cold. The adenovirus contains a DNA core which is surrounded by an icosahedral coat (capsid) made up of 252 capsomers (subunits). The pin-like protrusions are surface proteins. Adenovirus infections are common, particularly in children. The adenovirus is also believed to be associated with the transformation of ordinary cells into cancerous ones.