Viral classification

Viruses can be classified in several ways. The most useful is probably by the type of nucleic acid the virus contains, but they can also be classified:

by their geometry
by whether they have envelopes
by the identity of the host organism they can infect
by mode of transmission
by the type of disease they cause

Classification by type of constituent nucleic acid (i.e. by genome type), with examples:

Class I double stranded DNA.
- Papovavirus[?]
  - Papilloma[?] (human warts, cervical cancer)
  - Polyoma[?] (tumors in certain animals)
- Adenovirus[?]
  - Respiratory diseases, some cause turmors in certain animals
- Herpesvirus[?]
  - Herpes simplex I (cold sores)
  - Herpes simplex II (genital herpes)
  - Varicella zoster[?] (chicken pox, shingles)
  - Epstein-Barr virus (mononucleosis, Burkitt's lymphoma[?])
  - cytomegalovirus
- Poxvirus[?]
Class II single stranded DNA.
- Parvovirus (most depend on coinfection with adenoviruses for growth)
Class III double stranded RNA.
- Reovirus[?] (Diarrhea)
  - Rotavirus
Class IV positive single stranded RNA itself acting as mRNA.
- Coronavirus
- Picornavirus[?]
  - Poliovirus[?]
  - Rhinovirus (common cold)
  - Enteric viruses
- Togavirus
  - Rubella virus
  - Yellow fever virus
  - Encephalitis viruses
- hepatitis C virus
Class V negative single stranded RNA used as a template for mRNA synthesis.
Class VI positive single stranded RNA with a DNA intermediate in replication.
- Retrovirus
  - RNA tumor viruses (e.g., leukemia)
  - human immunodeficiency virus (HIV)
Class VII double stranded DNA with an RNA intermediate in replication.
- hepatitis B virus