Answer:
The three characteristics that adenoviruses, T7 viruses and papillomaviruses have in common include the following:
1. The three types of viruses possess icosahedral structures.
2. The viruses possess DNA.
3. Their DNA is double stranded.
Adenoviruses are naked (non enveloped) icosahedral nucleocapsid viruses, which has double stranded DNA genome. They are specific to vertebrate hosts and cause different types of diseases. T7 virus is a bacteriophage that infect bacterial cells. Most strain of E.coli are susceptible to this virus. Humanpapilloma viruses are small,naked icosahedral viruses which infect higher vertebrates.