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 retrovirises 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

External Links

• Retroviruses (http://users.rcn.com/jkimball.ma.ultranet/BiologyPages/R/Retroviruses.html)