Retrovirus
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:
- gag codes for core and structural proteins of the virus.
- pol codes for reverse transcriptase.
- 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).
- Spumavirinae with unknown effects.
All four identified
human retroviruses (
HTLV 1&2,
HIV 1&2) attack CD4 cells.
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.
- See also: HIV
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