A retrovirus is a virus which has a genome consisting of RNA. It relies on reverse transcriptase to perform a kind of reverse transcription of its genome from RNA into DNA for insertion by integrase into the host's genome. The virus itself is just a storage form for its RNA; the reverse transcription takes place in the host's cytosol. A retrovirus' genome integrated into the host's genome is called a provirus.
The retrovirus genome contains at least three genes:
gagcodes for core and structural proteins of the virus.
pol codes for reverse transcriptase, protease and integrase.
env codes for the virus hull proteins.
There are three known retrovirus categories :
Oncovirinae cause sarcomas and leukaemias (e.g., Rous Sarcoma Virus). They contain an onc gene which makes them oncogenic.
Lentivirinae cause slow progressive degenerative disorders (e.g., HIV).
Another feature common to all retroviruses is a lipid envelope surrounding their capsid. It is essential for their function. This explains why retroviruses can be killed by just washing hands.
