Author, Donkey, Bureaucrats, Administrators
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==Morphology==
*Fragile, enveloped RNA viruses with roughly spherical spike proteins
*Genome has 3 genes:
**''gag'': group-specific antigen coding gene, encodes capsid proteins
**''pol'': encodes reverse transcriptase (RT) and integrase
**''env'': encodes envelope spikes, and can be used in diagnosis and subunit vaccines
*Both ends of genome show a promoter (LTR: long terminal repeat)
==Antigenicity==
*Group-specific antigens (gag's) are shared by all isolates of each virus
**This can be exploited by diagnostic tests
*Lentiviruses show variation by mutation, making vaccination difficult
==Virulence and Pathogenesis==
*Replication involves integrating into the host cell genome:
**'''Uncoating''' to release RNA and RT
**+RNA '''transcribed''' to -DNA by RT
**-DNA becomes circular dsDNA and is '''integrated''' into host chromosome by integrase
**DNA '''codes''' for viral proteins using cellular organelles and enzymes
**Because of this technique, virus replication is much '''slower''', and retroviruses can remain '''latent'''
*Tumor production takes 2 forms:
**Viruses can carry oncogenes within their genome --> tumor production occurs quickly
**Insertion of the viral LTR switches on proto-oncogenes in the host cell genome --> tumor production can take years
Retrovirus virions are sensitive to heat, lipid solvents, and detergents but are relatively resistant to damage caused by ultraviolet light<sup>1</sup>. The Retroviridae are enveloped viruses which contain a single-stranded RNA genome within an icosahedral nucleocapsid. Glycoprotein surface spikes are located on the envelope. Unusually, Retroviruses have a diplod genome: two identical copies of their positive-sense ssRNA are found on the virion<sup>1</sup>. During viral replication, reverse transcriptase converts the ssRNA genome to ssDNA. This process is inherently error-prone, and the high rate of mutation gives rise to a wide genetic diversity of virus<sup>1</sup>. A dsDNA can then be made from the ssDNA template. This provirus DNA then becomes integrated into the host genome by the actions of the viral enzyme integrase, and remains latent until transcription is initiated by the host cell machinery<sup>1</sup>. Proviral DNA then serves as a template for the production of progeny ssRNA genomes and messenger RNA. Once the proviral DNA has been transcribe and translated, the virions assemble and are release by budding through the host cell membrane. This does not always cause lysis<sup>1</sup>.
Retrovirus virions are sensitive to heat, lipid solvents, and detergents but are relatively resistant to damage caused by ultraviolet light<sup>1</sup>. The Retroviridae are enveloped viruses which contain a single-stranded RNA genome within an icosahedral nucleocapsid. Glycoprotein surface spikes are located on the envelope. Unusually, Retroviruses have a diplod genome: two identical copies of their positive-sense ssRNA are found on the virion<sup>1</sup>. During viral replication, reverse transcriptase converts the ssRNA genome to ssDNA. This process is inherently error-prone, and the high rate of mutation gives rise to a wide genetic diversity of virus<sup>1</sup>. A dsDNA can then be made from the ssDNA template. This provirus DNA then becomes integrated into the host genome by the actions of the viral enzyme integrase, and remains latent until transcription is initiated by the host cell machinery<sup>1</sup>. Proviral DNA then serves as a template for the production of progeny ssRNA genomes and messenger RNA. Once the proviral DNA has been transcribe and translated, the virions assemble and are release by budding through the host cell membrane. This does not always cause lysis<sup>1</sup>.
[[Category:Retroviridae]]
[[Category:Retroviridae]]
[[Category:To Do - Viruses]]