Adenovirus

Adenoviruses are members of the family Adenoviridae. They are medium-sized (90–100 nm), nonenveloped viruses with an icosahedral nucleocapsid containing a linear double stranded DNA genome (between 26 and 48 Kbp). 

An interesting feature of this viral genome is that it has a terminal 55 kDa protein associated with each of the 5' ends of the linear dsDNA. These are used as primers in viral replication and ensure that the ends of the virus' linear genome are adequately replicated.